� � Feb-20-2012
Findings of a latest research show that flu viruses that have their origin in swine, which had resulted in about a dozen infections in the United States during the second half of 2011 seem to possess the potential of turning out to be an epidemic.
The work undertaken by scientists at the United States Centers for Disease Control appears to hint that the fact the human immunes system rather than the potential of these viruses are responsible for them to prosper in humans yet. The findings of the research by these scientists is founded on a transmission research conducted in ferrets, study that is rather akin to the researches which triggered to current debate over H5N1 viruses developed in the laboratory.
For many months till date, American as well as Dutch researchers have been endeavoring to bring out scientific papers demonstrating the manner in which they have developed H5N1 viruses (bird flu viruses) which have spread with no difficulty among ferrets, regarded as the most appropriate animal for forecasting the manner in which a flu virus may act in humans.
A group of experts, several of whom were invited from the realm of influenza research, agreed at a meeting of the World Health Organization (WHO) that the researches ought to be published in complete detail, regardless of a request from the United States government that crucial fractions of data should be beyond the public domain.
Findings of the latest research, which was published recently in the journal Proceedings of the National Academy of Sciences, entails the work with an H3N2 swine virus - presently named an H3N2 variation - that has resulted in infrequent human cases in the United States, counting a number of restricted person-to-person transmission.
It may be noted that the debate over the work on H5N1 is related to the reality that the research teams induced the hazardous viruses to develop to an extent where they transmit voluntarily among ferrets, something that may make the viruses developed in the laboratory also transmissible among humans. At present, H5N1 viruses rarely transmit to humans, but when they do, it is more often than not fatal.
During the course of research on the H3N2 variant, the scientists did not require applying force to the viruses to transform in such a manner that they were capable of infecting ferrets. In a recent interview, senior author Terrence Tumpey said that these viruses appear to be well-adapted to transmitting to mammals from before.
The research observed the H3N2 variant viruses over a long period from 2009, 2010 and 2011. During these three years, the viruses were found to have transformed. Especially, in 2011, the virus acquired a gene, called the M gene, from the H1N1 virus that was responsible for the pandemic in 2009.
When experimented in guinea pigs, the M gene appeared to make the flu virus additionally infectious. This fact resulted in the scientists to come to the hypothesis that the M gene may make it simpler for the swine viruses to contaminate people and may perhaps elucidate what seemed to be an augmentation in human cases in 2011.
In fact, this research raises questions regarding the finding, taking note of that the H3N2 variant viruses from 2010 were equally infectious in ferrets like the 2011 variant. The study stated that it is still uncertain if the taking up of the M gene actually increased the A(H3N2)v virus to transmit to pigs as well as transmit a disease to humans.
Senior author and a microbiologist, Terrence Tumpey said in a recent interview that these viruses - that are distantly related to the human H3N2 viruses - bind to the similar cell receptors to which the human flu viruses also attach. On the other hand, avian influenza viruses bind to dissimilar receptors that are not regular in the respiratory tract of the humans. This is the reason why it is believed that the H5N1 viruses do not transmit to humans very often.
Talking about the H3N2 variant viruses, Tumpey said that in general, for the comparatively latest viruses, the viruses examined in 2010 and 2011, one will notice very effectual transmission occurrences, something akin to what we find with the seasonal H3N2 viruses. He further said that these viruses possess the potential to become pandemic, but further information is required to genuinely comprehend the cross-reactive invulnerability among the common people to the H3N2 variant viruses.
Following 12 cases of infection between the period from July end to the late fall last year, no human has been infected by H3N2 variant viruses from the time prior to Christmas. According to Tumpey, a number of experts have been of the view that the cases of infection would decline following the season for agricultural fairs concludes. Several cases concerned exposure of people to ailing pigs at these types of occurrences.
Tumpey also took note of the fact that simply like flu has a particular season for infecting humans, contagions in pigs may heighten at different times of the year - and during such periods, even the risks of humans being infected by these viruses may increase. Tumpey further said that one more probable elucidation for the reason the viruses have not transmitted more widespread may perhaps be associated to the amount of immunity humans possess to these viruses.
It may be noted that in the early 1990s, the H3N2 viruses spread from the humans to the pigs and since that time the humans as well as pig versions have progressed along detached courses. It is generally believed that any individual who was born after the early 1990s will possibly not possess any antibody that would be able to indentify as well as provide protection from these viruses. However, people who were born prior to the early 1990s may possibly have the antibodies in their system.
The study stated that it is essential to find out more details regarding the immunity stages of the humans to these viruses as this will help to assess the extent of risk posed by this virus.
Meanwhile, a recently undertaken small research by the Canadian scientists hinted that there might be additional vulnerability to these new variant viruses in the humans compared to what one may suppose. The findings of this study were published in the journal Eurosurveillance and it did not find the presence on such antibodies in children as well as teens. However, the researchers detected potent levels of the antibodies in the young adults or youths. However, by the time one is of 40 years age, antibody levels begin to peter out sharply, the study undertaken by the Canadian scientists hinted.