.
"The 1977 pandemic spread rapidly worldwide but was limited to those under 20 years of age. Older persons were immune [via their]…exposures before 1957.…The consequences of escape of a highly lethal avian virus with enhanced transmissibility would almost certainly be much graver than the 1977 escape…to a population with substantial existing immunity.”
March 31, 2014, “Threatened pandemics and laboratory escapes: Self-fulfilling prophecies,” Bulletin of the Atomic Scientists, Martin Furmanski
“If a pathogen appears in nature after not circulating for years or decades, it may be assumed to have escaped from a laboratory where it had been stored inert for many years, accumulating no genetic changes; that is, its natural evolution had been frozen….The risk of a manmade pandemic sparked by a laboratory escape is not hypothetical: One occurred in 1977.”…
Human H1N1 influenza virus appeared to go extinct in 1957 after the H2N2 pandemic virus appeared.
Human H1N1 virus reappeared in 1977: “Virologists, using serologic and early genetic tests soon began to suggest the cause of the reappearance was a laboratory escape of a 1949-1950 virus,…By 2010, researchers published it as fact: “The most famous case of a released laboratory strain is the re-emergent H1N1 influenzaA virus which was first observed in China in May of 1977 and in Russia shortly thereafter.”…
The 1977 pandemic spread rapidly worldwide but was limited to those under 20 years of age: Older persons were immune from [their] exposures before 1957….Mercifully it caused mild disease, and fatalities were few. It continued to circulate until 2009, when the pH1N1 virus replaced it.
There has been virtually no public awareness of the 1977 H1N1 pandemic and its laboratory origins....The consequences of escape of a highly lethal avian virus with enhanced transmissibility would almost certainly be much graver than the 1977 escape of a “seasonal,” possibly attenuated strain to a population with substantial existing immunity.”
……………………………………………..
Added: Jan. 2006, Second citation for permanent natural immunity:
Jan. 2006, “Influenza Pandemics of the 20th Century,” cdc.gov, Edwin D. Kilbourne*
, Author affiliation: *New York Medical College, Valhalla, New York, USA
1977: Russian Flu, a Juvenile, Age-restricted Pandemic, and the Return of Human H1N1 Virus
Our obsession with geographic eponyms for a disease of worldwide distribution is best illustrated by Russian, or later red influenza or red flu, which first came to attention in November 1977, in the Soviet Union. However, it was later reported as having first occurred in northeastern China in May of that year [1977] (26).
It quickly became apparent that this rapidly spreading epidemic was almost entirely restricted to persons <25 years of age, and that, in general, the disease was mild, although characterized by typical symptoms of influenza.
The age distribution was attributed to the absence of H1N1 viruses in humans after 1957 and the subsequent successive dominance of the H2N2 and then the H3N2 subtypes.
When antigenic and molecular characterization of this virus showed that both the HA and NA antigens were remarkably similar to those of the 1950s, this finding had profound implications.
Where had the virus been that it was relatively unchanged after 20 years?
If serially (and cryptically) transmitted in humans, antigenic drift should have led to many changes after 2 decades. Reactivation of a long dormant infection was a possibility, but the idea conflicts with all we know of the biology of the virus in which a latent phase has not been found. Had the virus been in a deep freeze? This was a disturbing thought because it implied concealed experimentation with live virus, perhaps in a vaccine.”…
…………………………
Added: July 13, 2011: Third citation for permanent natural immunity: Virtually the entire global population born prior to 1957 was naturally immune to the 1977 version of H1N1 having been exposed years earlier and thus acquiring natural immunity:
July 13, 2011, “1977 Russian Flu Pandemic,” GlobalSecurity.org
“Strictly speaking, there was a fourth pandemic in the 20th century, an H1N1 strain which appeared in 1977. This was a “benign” pandemic, primarily involving persons born after 1950, because the older population had protective immunity resulting from prior experience with H1N1 strains.
The Russian Flu began in May 1977, when influenza A/H1N1 viruses isolated in northern China spread rapidly, and caused epidemic disease in children and young adults (< 23 years) worldwide….
It was later reported as having first occurred in northeastern China….In May 1977, influenza viruses in northern China spread rapidly and caused epidemic disease in children and young adults….
The age distribution was attributed to the absence of H1N1 viruses in humans after 1957 and the subsequent successive dominance of the H2N2 and then the H3N2 subtypes. The 1977 virus was similar to other A/H1N1 viruses that had circulated prior to 1957. In 1957, the A/H1N1 virus was replaced by the new A/H2N2 viruses….
Persons born before 1957 were likely to have been exposed to A/H1N1 viruses and to have developed immunity.…
Therefore, when the A/H1N1 reappeared in 1977, many people over the age of 23 had some protection against the virus and it was primarily younger people who became ill…By January 1978, the virus had spread around the world, including the United States.
Because illness occurred primarily in children, this event was not considered a true pandemic. Vaccine containing this virus was not produced in time for the 1977-78 season, but the virus was included in the 1978-79 vaccine….
Only a small portion of those over age 65 and the chronically ill over age 26 were attacked…
The predicted population group to be most seriously affected was attacked infrequently. HEW had predicted, based on past experience, that the 1978-79 flu would be most severe in the chronically ill and those over 65 years of age.
However, the population attacked most frequently were people under 26 years of age, and the disease consequences were generally mild in those attacked….
When antigenic and molecular characterization of this virus showed that both the HA and NA antigens were remarkably similar to those of the 1950s, this finding had profound implications. Where had the virus been that it was relatively unchanged after 20 years? If serially (and cryptically) transmitted in humans, antigenic drift should have led to many changes after two decades. Reactivation of a long dormant infection was a possibility, but the idea conflicted with what was known of the biology of the virus, in which a latent phase has not been found. Had the virus been in a deep freeze? This was a disturbing thought because it implied concealed [lab] experimentation with live virus, perhaps in a vaccine.” …
……………………..
Added: Peer reviewed study, 6/17/2010, confirms “disturbing thought” that 1977 H1N1 was result of “accidental release of a frozen laboratory strain” or “concealed experimentation:”
6/17/2010, “The Re-Emergence of H1N1 Influenza Virus in 1977: A Cautionary Tale for Estimating Divergence Times Using Biologically Unrealistic Sampling Dates,” Joel O. Wertheim, peer reviewed, …https://doi.org/10.1371/journal.pone.0011184
In 1977, H1N1 influenza A virus reappeared after a 20-year absence. Genetic analysis indicated that this strain was missing decades of nucleotide sequence evolution, suggesting an accidental release of a frozen laboratory strain into the general population. Recently, this strain and its descendants were included in an analysis attempting to date the origin of pandemic influenza virus without accounting for the missing decades of evolution. Here, we investigated the effect of using viral isolates with biologically unrealistic sampling dates on estimates of divergence dates. Not accounting for missing sequence evolution produced biased results and increased the variance of date estimates of the most recent common ancestor of the re-emergent lineages and across the entire phylogeny. Reanalysis of the H1N1 sequences excluding isolates with unrealistic sampling dates indicates that the 1977 re-emergent lineage was circulating for approximately one year before detection, making it difficult to determine the geographic source of reintroduction.
We suggest that a new method is needed to account for viral isolates with unrealistic sampling dates….
Introduction
Phylogenetic inference is an important tool for understanding the origin and evolution of emerging pathogens [1]. For rapidly evolving pathogens, such as RNA viruses, isolates sampled over years or decades can be used to calibrate a molecular clock and date divergence events [2]. However, if frozen laboratory strains escape into the general population, they will be missing years of nucleotide sequence evolution, and the date of isolation can be misleading.
The most famous case of a released laboratory strain is the re-emergent H1N1 influenza A virus which was first observed in China in May of 1977 and in Russia shortly thereafter [3], [4]. This outbreak marked the return of a seasonal H1N1 human influenza virus after a nearly 20-year absence following its displacement during the 1957 H2N2 pandemic. Scientists quickly realized that something was unusual about this re-emergent H1N1 strain; it was genetically similar, though not identical, to an H1N1 isolate from 1950 [5], [6]. Initially it was suggested that this virus could have lain dormant or evolved slowly in non-human hosts for decades, but it is now generally assumed that the virus was kept frozen in a yet unidentified laboratory[7], [8]. The glaring discrepancy between the amount of inferred evolutionary time (Figure 1A) and amount of sequence evolution (Figure 1B) leading to the 1977 outbreak provides evidence supporting this conclusion.”…
……………………..
............
No comments:
Post a Comment