The =
2005 completion=20
of the entire genome sequence of the 1918 H1N1 pandemic influenza =
virus=20
represents both a beginning and an end. Investigators have already =
begun=20
to study the virus in vitro and in vivo to better understand its=20
properties, pathogenicity, transmissibility and elicitation of =
host=20
responses. Although this is an exciting new beginning, =
characterization of=20
the 1918 virus also represents the culmination of over a century =
of=20
scientific research aiming to understand the causes of pandemic =
influenza.=20
In this brief review we attempt to place in historical context the =
identification and sequencing of the 1918 virus, including the =
alleged=20
discovery of a bacterial cause of influenza during the =
1889=E2=80=931893 pandemic,=20
the controversial detection of =E2=80=98filter-passing =
agents=E2=80=99 during the=20
1918=E2=80=931919 pandemic, and subsequent breakthroughs in the =
1930s that led to=20
isolation of human and swine influenza viruses, greatly =
influencing the=20
development of modern virology.
|
Discovery and characterization of the 1918 =
pandemic=20
influenza virus in historical context
Jeffery K =
Taubenberger,*=20
Johan V Hultin, and David M Morens
National Institute of Allergy and Infectious =
Diseases,=20
National Institutes of Health, Bethesda, MD, USA
*Corresponding author: Tel: +1 =
301 443 5960;=20
Fax: +1 301 480 5722; E-mail:
![3D"Small](3D"http://www.pubmedcentral.nih.gov/corehtml/pmc/pmcgifs/rt-arrow.gif=){kind=icon} =20
See other articles in PMC that cite=20
the published article. | ||||
|
|
Abstract
| |||
|
|
The announcement in =
2005 that a=20
virus causing fatal influenza during the great influenza pandemic =
of=20
1918=E2=80=931919 had been sequenced in its entirety [
| |||
|
|
In the =
pre-microbiological=20
era (before 1876) there was much confusion about the causes of =
both the=20
common communicable diseases like colds, smallpox, and measles, =
and the=20
great epidemic diseases like cholera and plague. Epidemiological =
notions=20
of carriers and intermediate vectors were not easily envisioned,=20
preventing many observers from accepting a unified concept of =
infectious=20
diseases, some of which were directly transmissible from person to =
person=20
(for example, smallpox), others of which were acquired from =
intermediate=20
vector hosts (for example, plague), still others of which were =
acquired=20
from contaminated environmental sources (for example, cholera) or =
were=20
acquired by more than one of the mechanisms just noted (for =
example,=20
smallpox and cholera).
In the pre-microbial =
era, influenza=20
had been considered among the more confusing of the pandemic =
diseases for=20
several reasons: (i) the signs and symptoms were non-specific, =
leading to=20
confusion with other conditions; (ii) interpandemic influenza-like =
illnesses were often attributed to other upper respiratory =
infections=20
(URIs), fuelling ongoing debates about whether interpandemic =
influenza=20
existed at all, or whether URIs were the same thing as =
interpandemic=20
influenza; (iii) pandemics occurred sporadically and =
unpredictably,=20
prompting debates about whether a new influenza-like disease was =
the same=20
as the one seen decades ago; and (iv) mortality statistics, which =
began to=20
appear in developed nations in the mid-1800s, showed high =
mortality only=20
for the first year or two of a pandemic, seeming to support the =
belief=20
that interpandemic influenza did not occur.
Each of four major =
influenza=20
pandemics before 1918, however, incrementally advanced scientific=20
understanding of the disease. The 1781=E2=80=931782 pandemic =
evolved so rapidly,=20
and was so widespread, that explosive outbreaks of febrile =
respiratory=20
illness in the general population alone became a distinguishing=20
characteristic, supporting the notion of a specific disease =
entity. The=20
1789=E2=80=931799 pandemic, coming soon thereafter, emphasized =
this recently=20
learned lesson. The 1830=E2=80=931833 pandemic, though less =
impressive, arrived at=20
about the same time as the second cholera pandemic =
(1831=E2=80=931833), of which=20
the inevitable march toward Europe was followed for over a year in =
the=20
daily newspapers, helping to establish a deep popular =
epidemiological=20
concept of pandemic diseases. The influenza pandemic of =
1847=E2=80=931851 nearly=20
coincided with the next (third) cholera pandemic =
(1849=E2=80=931855): this was the=20
pandemic in which British epidemiologist John Snow =
(1813=E2=80=931858) first=20
characterized the epidemiology and waterborne transmission of =
cholera [
A reputed cause of influenza =
identified=20
in 1892
It was in =
1892 that the=20
venerated physician/bacteriologist Richard Friedrich Johannes =
Pfeiffer=20
(1858=E2=80=931945), in partnership with physician/bacteriologist =
Shibasaburo=20
Kitasato (1852=E2=80=931931), both working in Berlin under Robert =
Koch=20
(1843=E2=80=931910), reported the discovery of a new bacterium [7], which Kitasato was able to cultivate and =
sustain on=20
artificial media [8], and which both scientists claimed to be the =
cause of=20
pandemic influenza. When their initial, brief, 1892 report was =
followed up=20
by more extensive data in 1893 [9], the scientific world was taken by storm; it =
seemed to=20
many that Pfeiffer had taken all of the necessary steps to =
establish=20
Bacillus influenzae, as he called it, as the true =
aetiological=20
agent of influenza. (B. influenzae was usually referred =
to as=20
=E2=80=98Pfeiffer=E2=80=99s bacillus=E2=80=99 in the literature of =
the late 19th and early 20th=20
centuries, and is now known as Haemophilus =
influenzae).
However, although =
B.=20
influenzae was clearly a pathogenic organism, and was often =
cultured=20
from fatal cases of influenza, other investigators were unable to =
confirm=20
Pfeiffer=E2=80=99s strong association, a problem compounded by the =
apparent=20
disappearance of pandemic influenza within a year or two of =
Pfeiffer=E2=80=99s=20
discovery. The verdict was unclear, but the notion that B.=20
influenzae was the true cause of influenza persisted up to =
the time=20
of the next pandemic in 1918 (see below), when Rockefeller =
scientists=20
Peter Kosciusko Olitsky (1886=E2=80=931964) and Frederick L Gates =
(1886=E2=80=931933)=20
provided strong evidence against a causal association, documenting =
that=20
the infective influenza agent survived passage through filters =
that=20
excluded B. influenzae [10].
Despite this bacterial =
blind=20
alley, it is important to note that most of the deaths during the=20
1918=E2=80=931919 influenza pandemic were associated with =
secondary bacterial=20
invaders (for review of clinical and pathological features of the =
1918=20
pandemic see [11]), among them H. influenzae, which =
Pfeiffer had=20
discovered. Pfeiffer, a budding 38-year-old researcher at the time =
of his=20
discovery, went on to have a long and distinguished career as an=20
originator of typhoid vaccination, the discoverer of bacteriolysis =
(=E2=80=98Pfeiffer=E2=80=99s phenomenon=E2=80=99), a =
conceptualizer of endotoxin, the discoverer=20
of the pathogenic organism Micrococcus (now =
Moraxella)=20
catarrhalis, and a tropical disease investigator of =
plague (in=20
India) and malaria (in Italy; [12=E2=80=9314]). Kitasato, who had already discovered the =
cause of=20
tetanus (1889) and had co-developed, with Emil von Behring =
(1854=E2=80=931917),=20
both tetanus and diphtheria antitoxins in 1890 [ | |||
|
|
By the turn of the =
19th/20th=20
century, Chamberland and Berkfeld filters were being manufactured =
and used=20
in research laboratories, allowing microbiologists to filter =
infectious=20
fluids to remove bacteria that were presumably too large to pass =
through=20
their pores. Using this technology, a variety of =
=E2=80=98filter-passing=E2=80=99 agents=20
were identified in short order, including the agents of foot and =
mouth=20
disease of cattle (1897=E2=80=931898; [21,22]), bovine pleuro-pneumonia [
| |||
|
|
At the time of the =
1918 influenza=20
pandemic, no-one suspected that the cause of the human disease was =
derived=20
from an avian infectious agent. Strong associations between some =
human=20
influenza epidemics and equine epizootics in the 19th century [ | |||
|
|
As noted, =
at the time of=20
the 1918 influenza pandemic, biomedical thinking about influenza =
was=20
dominated by Richard Pfeiffer=E2=80=99s 1892 claim that B. =
influenzae was=20
its cause [7]. Indeed, in 1918 Pfeiffer was still active and =
vocal in=20
making the case for the organism he had discovered [
The majority of =
individuals who=20
died during the 1918 pandemic succumbed to secondary bacterial =
pneumonia=20
[43=E2=80=9345], caused by Streptococcus pneumoniae,=20
Streptococcus pyogenes, H. influenzae,=20
Staphylococcus aureus, and other organisms. Moreover, a =
subset=20
died rapidly after the onset of symptoms, often with either =
massive acute=20
pulmonary haemorrhage or pulmonary oedema, and often in fewer than =
5 days.=20
In the hundreds of autopsies performed in 1918, the primary =
pathological=20
findings tended to be confined to the respiratory tree: death was =
due to=20
pneumonia and respiratory failure. These findings are consistent =
with=20
infection by a well adapted influenza virus capable of rapid =
replication=20
throughout the entire respiratory tree with little clinical or=20
pathological evidence for systemic virus infection [
The autumn wave of =
the 1918=20
pandemic proceeded so quickly that standardized research to =
investigate=20
the cause could not easily be set up. Nevertheless, during the =
autumn and=20
winter many researchers attempted to confirm or disprove =
Pfeiffer=E2=80=99s=20
claims, the latter by looking for filter-passing agents, something =
not=20
possible during the previous 1889 pandemic. The first to succeed, =
on 1=20
September 1918, were Nicolle and Lebailly, who claimed to have =
transferred=20
disease to two healthy volunteers via filtered sputum from a =
patient in=20
the third day of his illness [46]. Despite equivocal results from other =
investigators,=20
between December 1918 and March 1919 Yamanouchi and colleagues =
seemed to=20
confirm and extend the results of the French investigators in =
inoculation=20
experiments with 24 human volunteers [47]. Six of these volunteers had recovered from =
influenza;=20
the remaining 18 volunteers, who had not had detectable illness=20
beforehand, all developed influenza-like symptoms after a =
2=E2=80=933 day=20
incubation period, including those receiving filtered and =
unfiltered=20
nasopharyngeal inoculations of pooled infectious sputum.
Negative or =
more=20
equivocal results, as well as supporting results, were soon =
published [ | |||
|
|
It has often been =
true in science=20
that breakthroughs come from unexpected quarters. In 1931 =
Rockefeller=20
Institute investigator Richard E Shope (1901=E2=80=931966) =
published the first=20
three of a series of landmark papers [70=E2=80=9372] establishing the aetiology of =E2=80=98swine =
influenza=E2=80=99 or =E2=80=98hog=20
flu=E2=80=99, the new epizootic disease of pigs that had been =
noted initially=20
during the autumn wave of the 1918 influenza pandemic [
| |||
|
|
The =
work of Shope,=20
of Dochez and colleagues, and of the Mill Hill group led by =
Andrewes,=20
Smith and Laidlaw, resulted in the publication of hundreds of =
research=20
papers during the 1930s, making influenza the most studied and =
best=20
understood viral disease of its time. This body of work is too =
voluminous=20
to review here, but it can be said that efforts to characterize =
influenza=20
were a driving force behind the development of whole fields of=20
investigation and new research methods, including virology, =
serology and=20
immunology, experimental animal models, and modern vaccinology and =
passive=20
immunotherapy [78,79]. By the 1940s influenza B and distinctive =
strains of=20
influenza A had been identified, vaccines and immune serums had =
been=20
produced and tested, and a generation of young scientists had been =
stimulated to embark on careers in virology, among them Thomas =
Francis=20
(1900=E2=80=931969), who did perhaps more than any other scientist =
to characterize=20
influenza, Sir Charles Stuart-Harris (1909=E2=80=931997), who =
joined the Mill Hill=20
group and worked productively with many British and American =
colleagues,=20
Sir Frank Macfarlane Burnet (1899=E2=80=931985), the great Russian =
virologist=20
Anatolii Smorodintsev (1901=E2=80=931986), Maurice Hilleman =
(1919=E2=80=932005), and even=20
Jonas Salk (1914=E2=80=931995), whose early work with influenza =
vaccines [ | |||
|
|
Archaevirological search for =
the 1918=20
influenza in 1951
One of the =
co-authors=20
(JVH) was a student at the University of Iowa in 1949, beginning a =
PhD=20
program in microbiology. In 1950, Dr William Hale =
(1898=E2=80=931976), of=20
Brookhaven National Laboratory, visited the University. During a=20
discussion about the 1918 influenza pandemic, he commented =
=E2=80=98someone ought=20
to go to the frozen north to find a victim from 1918 in a =
permafrost=20
grave=E2=80=99. Immediately after that meeting, Hultin contacted =
his faculty=20
advisor, Dr Albert McKee (1913=E2=80=93), with a dissertation =
proposal: to find=20
such a permafrost grave in Alaska. Hultin began by collecting =
information=20
from Alaska, most importantly from the palaeontologist Otto Geist=20
(1888=E2=80=931962). With Geist=E2=80=99s help, Hultin contacted =
several Alaskan missions=20
about their 1918 experiences.
By 1951, all such =
mission=20
communications had been received. Three sites along the coast of =
the=20
Seward Peninsula were selected for further study: Nome, Wales, and =
Brevig=20
Mission. The selection was based on epidemiological evidence =
indicating=20
high pandemic fatality in the Inuit population. In Nome more than =
half of=20
the native population had died, in Teller 53%, in Brevig Mission =
(then=20
called Teller Mission) 90%, in York 100%, and in Wales 55% [
In June 1951, an =
expedition=20
consisting of Hultin, McKee, and the team=E2=80=99s renowned =
pathologist Jack M=20
Layton (1917=E2=80=93), left for Alaska. At Brevig Mission the =
permafrost=20
conditions were promising, and permission to perform an exhumation =
was=20
obtained. The team, joined in Alaska by Geist, made rapid progress =
digging. Reaching a depth of 2 m, a layer of bodies was =
discovered, placed=20
side by side. Layton opened the rib cages of four bodies, exposing =
frozen,=20
dark red, expanded lungs. Generous biopsies from eight lungs were =
obtained=20
and, while still frozen, placed in sterile containers that were =
then put=20
into thermal jugs and kept frozen with carbon dioxide snow from =
fire=20
extinguishers. The instruments used were sterilized in boiling =
water at=20
the graveside; surgical masks were used, as were sterile =
gloves.
In the =
microbiology=20
laboratory at the University of Iowa, this material was cultured =
in=20
embryonated eggs using available containment procedures of the =
time,=20
including use of face masks, gloves and special pipettes, with all =
work=20
done under a negative-pressure hood. Five susceptible ferrets =
received=20
nasal instillations. The ferrets showed no signs of illness. =
Cultures from=20
the lung material of some of the specimens grew H. =
influenzae and=20
S. pneumoniae. Histological analyses showed a =
predominating=20
pattern of acute viral pneumonitis, although some sections showed =
acute=20
bacterial pneumonias. All of the available specimens were =
processed but no=20
influenza virus was recovered. Unfortunately, all of the materials =
from=20
this project were subsequently discarded. As Alfred Crosby stated =
in his=20
book America=E2=80=99s Forgotten Pandemic, =E2=80=98the =
most direct assault on=20
Spanish influenza had failed=E2=80=99 [82]. He also wrote [83]: =E2=80=98It has been the dream of scientists =
working on=20
influenza for over a half century to somehow obtain specimens of =
the virus=20
of Spanish influenza, but only something as unlikely as a time =
capsule=20
could provide them.=E2=80=99 Archaevirological search for =
the 1918=20
influenza in 1995
Forty-five years =
later, in 1995,=20
the search for this time capsule was resumed when co-author JKT =
began a=20
project to recover RNA fragments of the 1918 influenza virus from=20
formalin-fixed, paraffin-embedded (FFPE) autopsy tissues in the =
collection=20
of the National Tissue Repository of the Armed Forces Institute of =
Pathology (AFIP). In the mid-1990s the Molecular Pathology =
Division of the=20
AFIP had been engaged in developing and optimizing diagnostic =
molecular=20
assays for neoplastic and infectious diseases that could be =
applied to=20
FFPE tissues [84]. Projects undertaken simultaneously to =
characterize=20
novel morbilliviruses from marine mammal epizootics [
After reading the =
initial paper in=20
1997 on the characterization of RNA fragments obtained from the =
first AFIP=20
1918 case, Hultin wrote to Taubenberger, detailing the Iowa =
expedition=E2=80=99s=20
work at Brevig Mission in 1951, and offering to return to Alaska =
for a=20
second exhumation to secure additional specimens for molecular =
analysis.=20
At a special meeting of the Brevig City Council, permission to =
reopen the=20
graves was granted. One of the victims found was an obese female =
whose=20
body was well preserved. On further excavation, two skeletons were =
found,=20
one on either side of her. It is likely that the subcutaneous =
fatty tissue=20
of the obese woman had preserved the internal organs from =
decomposition=20
during occasional short periods of thawing within the permafrost. =
Her=20
lungs displayed the gross appearance of those seen in acute viral=20
pneumonitis, expanded and dark red in colour. Samples of frozen =
lung were=20
placed directly in fixatives, including ethanol and =
guanidine.
Determining the =
complete coding=20
sequence of the 1918 virus took 9 years, including publication of =
the=20
neuraminidase (NA) segment in 2000 [89], the non-structural segment in 2001 [ Reconstruction of the 1918 =
virus
The development of =
reverse=20
genetics technology for influenza viruses in 1999 [
Viral constructs =
bearing at least=20
1918 HA and NA genes in a background of modern, non-mouse-adapted =
human=20
H1N1 virus, are all highly pathogenic in mice [
The viral genotypical =
basis of=20
this virulence has not yet been mapped, and its relevance for =
human=20
pathogenesis also remains unclear. The murine pathology, although=20
reminiscent of some of the acute viral pneumonia pathology seen in =
1918=20
autopsy studies [11], is nevertheless distinctive. The roles of the =
other=20
1918 proteins, singularly and in combination, are currently =
unknown.=20
However, the reconstructed all-eight-gene 1918 influenza virus is =
more=20
virulent than constructs containing fewer 1918 genes, suggesting=20
contributions of each gene segment to virulence [
Viral sequence data =
now suggest=20
that the entire 1918 virus was novel to humans in, or shortly =
before,=20
1918, and that it was not likely to have been a reassortant virus =
such as=20
those that caused the 1957 and 1968 pandemics [
In =
collaboration with Dr=20
John Oxford, a new project to expand knowledge of human influenza =
virus=20
circulation before 1918 was initiated in 2004, using additional =
samples=20
from the post mortem tissue archives of the Royal London hospital. =
Recently, several pre-1918-human-influenza-A-RNA-positive cases =
have been=20
identified and initial genetic characterization is ongoing =
(unpublished).=20
The goal of this project is twofold: (i) to determine what =
subtype(s)=20
circulated in humans before 1918, and (ii) to determine whether =
any=20
previously human-adapted influenza gene segments were retained in =
the 1918=20
pandemic virus. Concurrently, autopsy specimens from influenza =
cases from=20
the 1920s and 1930s are also being examined to characterize the =
early=20
evolution of human H1N1 viruses prior to the first H1N1 isolations =
in the=20
1930s; several influenza A RNA-positive cases from the 1920s have =
already=20
been identified and are now being studied. If there are specific =
genotypic=20
traits that gave the 1918 virus its particular virulence for young =
adults,=20
comparing it experimentally with less pathogenic descendant =
viruses from=20
the early 1920s might be especially =
informative. | |||
|
|
The =
current=20
projects to understand the origin of the 1918 influenza pandemic =
virus and=20
its virulence characteristics rest on a solid foundation of =
influenza=20
virology and epidemiology developed over the last century. It is =
hoped=20
that additional insights into the mechanisms of viral host =
adaptation and=20
the mechanisms of how influenza viruses cause disease in their =
human and=20
experimental hosts will come from future work with the =
reconstructed 1918=20
virus. Looking backward in time, but also looking forward into the =
future,=20
we can see that science stands in the middle of a long and =
continuing line=20
of effort to comprehend history=E2=80=99s most devastating human =
disease. We must=20
also be aware that revealing the biology of a pandemic that =
occurred=20
nearly 90 years ago is not just a historical exercise. It may well =
help us=20
prepare for, and even prevent, the emergence of new pandemics in =
the 21st=20
century and beyond. | |||
|
For assistance in obtaining =
historical=20
manuscripts we are grateful to Steven Greenberg, PhD and the staff =
of the=20
History of Medicine Division, to Deirdre Clarkin and the staff of =
the=20
Public Services Division, National Library of Medicine, and to =
Betty=20
Murgolo and the staff of the National Institutes of Health=20
Library. | ||||
|
|
References
1.
Taubenberger JK, Reid AH, Lourens RM, Wang =
R, Jin G,=20
Fanning TG. Characterization of the 1918 influenza virus =
polymerase genes.=20
Nature. 2005; 2.
Webster RG, Peiris M, Chen H, Guan Y. H5N1 =
outbreaks=20
and enzootic influenza. Emerg =
Infect Dis.=20
2006;12:3=E2=80=938. =
3.
Snow J. On the =
Mode of=20
Communication of Cholera. 2. London: John Churchill; 1855. =
much=20
enlarged. 4.
Rahts Die Influenza-epidemie des Winters =
1893/94 im=20
Deutschen Reiche [The influenza epidemic of the Winter of 1893/94 =
in the=20
German Empire]. Arbeiten aus dem=20
Kaiserlichen Gesundheitsamte. 1896; 5.
Kendal AP, Minuse E, Maassab HF, Hennessy =
AV,=20
Davenport FM. Influenza neuraminidase antibody patterns of man.=20
Am J Epidemiol. 1973; 6.
Koch R. Die Aetiologie der =
Milzbrand-Krankheit,=20
begr=C3=BCndet auf die Entwicklungsgeschichte der Bacillus =
Anthracis [The=20
aetiology of the illness of anthrax, based on the developing =
history of=20
Bacillus anthracis]. Beitr=C3=A4ge =
zur Biologie=20
der Pflanzen (Breslau [Wroclaw]). 1876; 7.
Pfeiffer R. Aus dem Institut f=C3=BCr=20
Infektionskrankheiten. II. Vorl=C3=A4ufige Mittheilungen =C3=BCber =
die Erreger der=20
Influenza [From the Institute for Infectious Diseases. II. =
Provisional=20
communication on the cause of influenza]. 8.
Kitasato S. Aus dem Institut f=C3=BCr=20
Infektionskrankheiten. III. Ueber den Influenzabacillus und sein=20
Culturverfahren [From the Institute for Infectious Diseases. III. =
On the=20
influenza bacillus and its method of cultivation]. 9.
Pfeiffer R. Die Aetiologie der Influenza =
[The=20
aetiology of influenza]. Zeitschrift f=C3=BCr=20
Hygiene und Infektionskrankheiten; medizinische Mikrobiologie, =
Immunologie=20
und Virologie. 1893; 10.
Olitsky P, Gates F. Experimental study of =
the=20
nasopharyngeal secretions from influenza patients. 11.
Taubenberger JK, Morens DM. 1918 Influenza: =
the mother=20
of all pandemics. Emerg Infect =
Dis.=20
2006;12:15=E2=80=9322. =
12.
Pfeiffer R, Kolle W. Ueber die specifische=20
Immunit=C3=A4tsreaction der Typhusbacillen [On the specific immune =
reaction to=20
the typhus bacillus]. Zeitschrift =
f=C3=BCr=20
Hygiene und Infektionskrankheiten. 1895=E2=80=931896; 13.
Pfeiffer R, Kolle W. Experimentelle =
Untersuchungen zur=20
Frage de Schutzimpfung des Menschen gegen Typhus abdominalis =
[Experimental=20
investigations on the question of human immunization against =
Typhus=20
abdominalis]. Deutsche =
medizinische=20
Wochenschrift. 1896; 14.
Rietschel E, Cavaillon J-M. Richard Pfeiffer =
and=20
Alexandre Besredka: creators of the concept of endotoxin and=20
anti-endotoxin. Microbes Infect.=20
2003;5:1407=E2=80=931414. 15.
Kitasato S. Ueber den Tetanusbacillus [On =
the tetanus=20
bacillus]. Zeitschrift f=C3=BCr =
Hygiene und=20
Infektionskrankheiten; medizinische Mikrobiologie, Immunologie und =
Virologie. 1889; 16.
von Behring E, Kitasato S. Ueber das =
Zustandekommen=20
der Diptherie-Immunit=C3=A4t und der Tetanus-Immunit=C3=A4t bei =
Thieren [On the=20
development of diphtheria immunity and tetanus immunity in =
animals].=20
Deutsche medizinische =
Wochenschrift.=20
1890; 17.
Kitasato S. The bacillus of bubonic plague.=20
Lancet. 1894; 18.
Ivanovski D. Ueber die Mosaikkrankheit der=20
Tabakspflanze [On the mosaic disease of tobacco plants]. =
19.
Beijerinck M. Over een Contagium vivum =
fluidum als=20
oorzaak van de Vlekziekte der Tabaksbladen [Concerning a contagium =
vivum=20
fluidum as cause of the spot disease of tobacco leaves]. =
20.
Wilkinson L. The development of the virus =
concept as=20
reflected in corpora of studies on individual pathogens. 1. =
Beginnings at=20
the turn of the century. Med Hist. =
1974;18:211=E2=80=93221. 21.
Loeffler F, Frosch P. Summarischer Bericht =
=C3=BCber die=20
Ergebnisse der Untersuchungen der Kommission zur Erforschung der =
Maul- und=20
Klauenseuche bei dem Institut f=C3=BCr Infektionskrankheiten in =
Berlin [Summary=20
report on the outcomes of the investigation of the commission for=20
researching foot and mouth disease of the Institute for Infectious =
Diseases in Berlin]. Centralblatt =
f=C3=BCr=20
Bakteriologie, Parasitenkunde und Infektionskrankheiten 1 =
Abteilung:=20
medizinische-hygienische Bakteriologie und tierische =
Parasitenkunde.=20
1897; 22.
Loeffler F, Frosch P. Bericht der Kommission =
zur=20
Erforschung der Maul- und Klauenseuche bei dem Institut f=C3=BCr=20
Infektionskrankheiten in Berlin [Report of the commission for =
researching=20
foot and mouth disease of the Institute for Infectious Diseases in =
Berlin]. Centralblatt f=C3=BCr Bakteriologie und =
Infektionskrankheiten. 2=20
naturwissenschaftenliche Abteilung: Allgemeine,=20
land-wirtschaftliche-technologische Bakteriologie. =
23.
Nocard E, Roux P. Le microbe de la =
peripneumonie [The=20
microbe of peripneumonia]. Annales =
de=20
l=E2=80=99Institut Pasteur. 1889; 24.
Sanarelli G. Das myxomatogene Virus [The=20
myxomatogenous virus]. Centralblatt f=C3=BCr=20
Bakteriologie, Parasitenkunde und Infektionskrankheiten 1 =
Abteilung:=20
medizinische-hygienische Bakteriologie und tierische =
Parasitenkunde.=20
1898; 25.
M=E2=80=99fadyean J. African horse-sickness. =
26.
Roux =C3=89. Sur les microbes dites =
=E2=80=9Cinvisibles=E2=80=9D [On the=20
microbes known as =E2=80=98invisible=E2=80=99]. Bulletin de=20
l=E2=80=99Institut Pasteur. 1903;1:7=E2=80=9312.=20
49=E2=80=9356. 27.
Remlinger P. Les microbes filtrants [The=20
filter-passing microbes]. Bulletin =
de=20
l=E2=80=99Institut Pasteur. 1906;4:337=E2=80=93345.=20
385=E2=80=93392. 28.
Foster G. The etiology of common colds. The =
probable=20
role of a filtrable virus as the causative factor: with =
experiments on the=20
cultivation of a minute micro-organism from the nasal secretion =
filtrates.=20
J Infect Dis. 1917; 29.
Fleming G. Animal =
Plagues:=20
History, Nature and Prevention. Vol. 1. London: =
Bailli=C3=A8re, Tindall=20
& Cox; 1871. 30.
Chun J. Influenza including its infection =
among pigs.=20
Nat Med J. =
1919=E2=80=931920; 31.
Koen J. A practical method for field =
diagnosis of=20
swine diseases. Am J Vet Med.=20
1919; 32.
Perroncito E. Epizoozia tifoide nei =
gallinacei=20
[Epizootic of typhoid in gallinaceous birds]. 33.
Lode A, Gruber F. Bakteriologische Studien =
=C3=BCber die=20
Aetiologie einer epidemischen Erkrankung der H=C3=BChner in Tirol =
(1901)=20
[Bacteriological studies on the aetiology of epidemic illness of =
chickens=20
in Tirol (1901)]. Centralblatt =
f=C3=BCr=20
Bakteriologie, Parasitenkunde und Infektionskrankheiten 1 =
Abteilung:=20
medizinische-hygienische Bakteriologie und tierische =
Parasitenkunde.=20
1901; 34.
Centanni E. Die Vogelpest. Beitrag zu dem =
durch Kerzen=20
filtrierbaren Virus [Fowl plague. Report on the candle filterable =
virus].=20
Centralblatt f=C3=BCr =
Bakteriologie,=20
Parasitenkunde und Infektionskrankheiten 1 Abteilung:=20
medizinische-hygienische Bakteriologie und tierische =
Parasitenkunde.=20
1902; 35.
Maggiora A, Valenti G. Ueber eine Seuche von =
exsudtivem Typhys bei H=C3=BChnern. I. Mittheilung [Regarding an =
epidemic of=20
exudative typhus in chickens. Part =
I]=20
Zeitschrift f=C3=BCr Hygiene und Infektionskrankheiten; =
medizinische=20
Mikrobiologie, Immunologie und Virologie. 1903; 36.
Sch=C3=A4fer W. Vergleichende =
sero-immunologische=20
Untersuchungen =C3=BCber die Viren der Influenza und klassichen =
Gefl=C3=BCgelpest=20
[Comparative sero-immunological investigations on the viruses of =
influenza=20
and classical fowl plague]. Zeitschrift f=C3=BCr=20
Naturforschung. 1955; 37.
Pereira HG, Tumov=C3=A1 B, Law VG. Avian =
influenza A=20
viruses. Bulletin of the World =
Health=20
Organization. 1965;32:855=E2=80=93860.=20
[PubMed] 38.
Pereira HG, Tumov=C3=A1 B, Webster RG. =
Antigenic=20
relationship between influenza A viruses of human and avian =
origins.=20
Nature. 1967; 39.
Slemons RD, Johnson DC, Osborn JS, Hayes F. =
Type A=20
influenza viruses isolated from wild free-flying ducks in =
California.=20
Avian Diseases. 1974; 40.
Webster RG, Bean WJ, Gorman OT, Chambers TM, =
Kawaoka=20
Y. Evolution and ecology of influenza A viruses. 41.
Pfeiffer R. Das Influenzaproblem [The =
influenza=20
problem]. Ergebnisse der Hygiene,=20
Bakteriologie, Immunit=C3=A4tsforschung und experimentellen =
Therapie.=20
1922;5:1=E2=80=9318. 42.
Pfeiffer R. Neuere Forschungen zur =
Kl=C3=A4rung der=20
Influenza=C3=A4tiologie [New research to clarify the aetiology of =
influenza].=20
Deutsche medizinische =
Wochenschrift.=20
1925;51:10=E2=80=9313. 43.
LeCount E. The pathologic anatomy of =
influenzal=20
bron-chopneumonia. J Am Med Assoc. =
1919; 44.
Wolbach S. Comments on the pathology and =
bacteriology=20
of fatal influenza cases, as observed at Camp Devens, Mass. =
45.
Winternitz M, Wason I, McNamara F. 46.
Nicolle C, Lebailly C. Quelques notions =
exp=C3=A9rimentales=20
sur le virus de la grippe [Certain experimental ideas about the =
infectious=20
agent of influenza]. Comptes =
rendus de=20
l=E2=80=99Acad=C3=A9mie des Sciences. 1918; 47.
Yamanouchi T, Sakakami K, Iwashima S. The =
infecting=20
agent in influenza. an =
experimental research=20
Lancet. 1919; 48.
Selter H. Zur Aetiologie der Influenza [On =
the=20
aetiology of influenza]. Deutsche=20
medizinische Wochenschrift. 1918; 49.
Keegan J. The prevailing pandemic of =
influenza.=20
J Am Med Assoc. 1918; 50.
Dujarric de la Rivi=C3=A8re M. La grippe =
est-elle une=20
maladie =C3=A0 virus filtrant? [Is influenza a disease of =
filter-passing=20
microbes?]. Comptes rendus de =
l=E2=80=99Acad=C3=A9mie des=20
Sciences. 1918; 51.
Gibson H, Bowman F, Connor J. A filtrable =
virus as the=20
cause of the early stage of the present epidemic of influenza. =
52.
von Angerer Ein filtrierbaren Erreger der =
Grippe [A=20
filterable cause of influenza]. M=C3=BCnchener=20
medizinische Wochenschrift. 1918; 53.
Binder A. Studien zur Aetiologie der =
Influenza. I. Zur=20
mikroskopischen Diagnose der Influenza [Studies on the aetiology =
of=20
influenza. I. On the microscopic diagnosis of influenza]. =
54.
Prell H., II Die Erreger der Influenza [The =
causes of=20
influenza]. M=C3=BCnchener =
medizinische=20
Wochenschrift. 1918; 55.
Leschke E. Untersuchungen zur Aetiologie der =
Grippe=20
[Studies on the aetiology of influenza]. 56.
Bradford J, Bashford E, Wilson J. =
Preliminary report=20
on the presence of a =E2=80=9Cfilter passing=E2=80=9D virus in =
certain diseases, with=20
especial reference to trench fever, influenza, and nephritis. =
57.
Cummins S. Cultivation of a =
filter=E2=80=93passing organism in=20
influenza. Lancet. =
1919; 58.
Lister F. A filter-passing micro-organism =
associated=20
with influenza. South African =
Medical=20
Record. 1922; 59.
Arkwright J. A criticism of certain recent =
claims to=20
have discovered and cultivated the filter-passing virus of trench =
fever=20
and of influenza. Brit Med J.=20
1919;2:233=E2=80=93236. 60.
Fejes L. Die Aetiologie der Influenza [The =
aetiology=20
of influenza]. Deutsche =
medizinische=20
Wochenschrift. 1919; 61.
Maitland H, Cowan M, Detweiler H. The =
aetiology of=20
epidemic influenza: experiments in search of a filter-passing =
virus.=20
Brit J Exp Path. 1920;1:263=E2=80=93281. 62.
Hall M. A study of the lesions produced by =
filtrates=20
of influenza sputum. Arch Int Med. =
1920; 63.
Loewe L, Zeman F. Cultivation of a filtrable =
organism=20
from the nasopharyngeal washings in influenza. 64.
Abe T, Ishikawa T, Nishibe M, Nakata I, =
Tenjin S.=20
Influenza Research Committee, The =
Government=20
Institute for Infectious Diseases. Tokyo: Tokyo Imperial=20
University; 1922. An experimental study of filtering property of =
influenza=20
virus upon certain animals. Studies on Influenza From the =
Influenza=20
Research Committee of the Institute, December 28, 1922; pp.=20
29=E2=80=9333. 65.
Gordon M. The filter passer of influenza. =
The=20
properties of filtrable viruses. J =
Roy Army=20
Med Corps. 1922; 66.
Woodcock H. Are the active principles of=20
filter-passing and =E2=80=9Cultramicroscopic=E2=80=9D viruses =
living organisms or enzymes?=20
J Roy Army Med Corps. =
1922; 67.
Detweiler H, Hodge W. An attempt to isolate =
a=20
filter-passing virus in epidemic influenza. 68.
Bo=C3=ABz L. Les microbes filtrables des =
voies=20
respiratoires dans l=E2=80=99influenza et le coryza aigu =
[Filterable microbes of=20
the respiratory tract in influenza and acute coryza]. 69.
Rosenau MJ, Keegen WJ, Goldberger J, Lake =
GC.=20
Experiments upon volunteers to determine the cause and mode of =
spread of=20
influenza, Boston, November and December 1918. 70.
Shope R. Swine influenza. I. Experimental =
transmission=20
and pathology. J Exp Med. =
1931; 71.
Lewis P, Shope R. Swine influenza. II. A =
hemophilic=20
bacillus from the respiratory tract of infected swine. J Exp Med. 1931; 72.
Shope R. Swine influenza. III. Filtration =
experiments=20
and etiology. J Exp Med. =
1931; 73.
Kanegae Y, Sugita S, Shortridge KF, Yoshioka =
Y, Nerome=20
K. Origin and evolutionary pathways of the H1 hemagglutinin gene =
of avian,=20
swine and human influenza viruses: cocirculation of two distinct =
lineages=20
of swine virus. Arch Virol.=20
1994;134:17=E2=80=9328. =
74.
Taubenberger JK, Reid AH, Janczewski TA, =
Fanning TG.=20
Integrating historical, clinical and molecular genetic data in =
order to=20
explain the origin and virulence of the 1918 Spanish influenza =
virus.=20
Philos Trans R Soc Lond B Biol =
Sci.=20
2001;356:1829=E2=80=931839. 75.
Nakajima K, Desselberger U, Palese P. Recent =
human=20
influenza A (H1N1) viruses are closely related genetically to =
strains=20
isolated in 1950. Nature. =
1978; 76.
Dochez A, Mills K, Kneeland Y. Studies of =
the etiology=20
of influenza. Proc Soc Exp Biol =
Med.=20
1934=E2=80=931935; 77.
Smith W, Andrewes C, Laidlaw P. A virus =
obtained from=20
influenza patients. Lancet.=20
1933;2:66=E2=80=9368. =
78.
Francis T, Magill T. The antibody response =
of human=20
subjects vaccinated with the virus of human influenza. J Exp Med. 1937; 79.
Smorodintsev A, Shishkina O. Experimental =
analysis of=20
immune sera. Arkhiv =
biologicheskikh nauk.=20
1938; 80.
Salk J, Lavin G, Francis T. The antigenic =
potency of=20
epidemic influenza virus following inactivation by ultraviolet =
radiation.=20
J Exp Med. 1940; 81.
Crosby A. America=E2=80=99s Forgotten=20
Pandemic. 2. New York: Cambridge University Press; 2003. p. =
337. 82.
Crosby A. America=E2=80=99s Forgotten=20
Pandemic. 2. New York: Cambridge University Press; 2003. p. =
306. 83.
Crosby A. America=E2=80=99s Forgotten=20
Pandemic. 2. New York: Cambridge University Press; 2003. p. =
295. 84.
Krafft AE, Duncan BW, Bijwaard KE, =
Taubenberger JK,=20
Lichy JH. Optimization of the isolation and amplification of RNA =
from=20
formalin-fixed, paraffin-embedded tissue: The Armed Forces =
Institute of=20
Pathology experience and literature review. 85.
Taubenberger JK, Tsai M, Krafft AE, et al. =
Two=20
morbilliviruses implicated in bottlenose dolphin epizootics. =
86.
Hunt DM, Dulai KS, Bowmaker JK, Mollon JD. =
The=20
chemistry of John Dalton=E2=80=99s color blindness. 87.
Taubenberger JK, Reid AH, Krafft AE, =
Bijwaard KE,=20
Fanning TG. Initial genetic characterization of the 1918 =
=E2=80=9CSpanish=E2=80=9D=20
influenza virus. Science. =
1997; 88.
Reid AH, Fanning TG, Hultin JV, Taubenberger =
JK.=20
Origin and evolution of the 1918 =E2=80=9CSpanish=E2=80=9D =
influenza virus hemagglutinin=20
gene. Proc Natl Acad Sci U S A.=20
1999;96:1651=E2=80=931656. 89.
Reid AH, Fanning TG, Janczewski TA, =
Taubenberger JK.=20
Characterization of the 1918 =E2=80=9CSpanish=E2=80=9D influenza =
virus neuraminidase gene.=20
Proc Natl Acad Sci U S A. =
2000; 90.
Basler CF, Reid AH, Dybing JK, et al. =
Sequence of the=20
1918 pandemic influenza virus nonstructural gene (NS) segment and=20
characterization of recombinant viruses bearing the 1918 NS genes. =
Proc Natl Acad Sci U S A. =
2001; 91.
Reid AH, Fanning TG, Janczewski TA, McCall =
S,=20
Taubenberger JK. Characterization of the 1918 =
=E2=80=9CSpanish=E2=80=9D influenza virus=20
matrix gene segment. J Virol.=20
2002;76:10717=E2=80=9310723. 92.
Reid AH, Fanning TG, Janczewski TA, Lourens =
RM,=20
Taubenberger JK. Novel origin of the 1918 pandemic influenza virus =
nucleoprotein gene. J Virol.=20
2004;78:12462=E2=80=9312470. 93.
Reid AH, Janczewski TA, Lourens RM, et al. =
1918=20
influenza pandemic caused by highly conserved viruses with two=20
receptor-binding variants. Emerg =
Infect Dis.=20
2003;9:1249=E2=80=931253. 94.
Neumann G, Watanabe T, Ito H, et al. =
Generation of=20
influenza A viruses entirely from cloned cDNAs. 95.
Fodor E, Devenish L, Engelhardt OG, Palese =
P, Brownlee=20
GG, Garcia-Sastre A. Rescue of influenza A virus from recombinant =
DNA.=20
J Virol. 1999; 96.
Tumpey TM, Garcia-Sastre A, Mikulasova A, et =
al.=20
Existing antivirals are effective against influenza viruses with =
genes=20
from the 1918 pandemic virus. Proc =
Natl Acad=20
Sci U S A. 2002;99:13849=E2=80=9313854.=20
[PubMed] 97.
Tumpey TM, Garcia-Sastre A, Taubenberger JK, =
Palese P,=20
Swayne DE, Basler CF. Pathogenicity and immuno-genicity of =
influenza=20
viruses with genes from the 1918 pandemic virus. 98.
Tumpey TM, Basler CF, Aguilar PV, et al.=20
Characterization of the reconstructed 1918 Spanish influenza =
pandemic=20
virus. Science. 2005; 99.
Tumpey TM, Garcia-Sastre A, Taubenberger JK, =
et al.=20
Pathogenicity of influenza viruses with genes from the 1918 =
pandemic=20
virus: functional roles of alveolar macrophages and neutrophils in =
limiting virus replication and mortality in mice. 100.
Kash JC, Basler CF, Garcia-Sastre A, et al. =
Global=20
host immune response: pathogenesis and transcriptional profiling =
of type A=20
influenza viruses expressing the hemagglutinin and neuraminidase =
genes=20
from the 1918 pandemic virus. J =
Virol.=20
2004;78:9499=E2=80=939511. 101.
Kash JC, Tumpey TM, Proll SC, et al. Genomic =
analysis=20
of increased host immune and cell death responses induced by 1918=20
influenza virus. Nature. =
2006; 102.
Rabadan R, Levine AJ, Robins H. Comparison =
of avian=20
and human influenza A viruses reveals a mutational bias on the =
viral=20
genomes. J Virol. =
2006; 103.
Reid AH, Taubenberger JK, Fanning TG. =
Evidence of an=20
absence: the genetic origins of the 1918 pandemic influenza virus. =
Nat Rev Microbiol. =
2004; 104.
Fanning TG, Slemons RD, Reid AH, Janczewski =
TA, Dean=20
J, Taubenberger JK. 1917 avian influenza virus sequences suggest =
that the=20
1918 pandemic virus did not acquire its hemagglutinin directly =
from birds.=20
J Virol. 2002; 105.
Reid AH, Fanning TG, Slemons RD, Janczewski =
TA, Dean=20
J, Taubenberger JK. Relationship of pre-1918 avian influenza HA =
and NP=20
sequences to subsequent avian influenza strains. | |||
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