PLoS Currents Influenza. Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection: Evidence of competitive advantage of pandemic

[Giuseppe]

Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection (Abstract, edited)

Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection: Evidence of competitive advantage of pandemic H1N1 influenza versus seasonal influenza

Daniel Perez,* Erin Sorrell,? Matthew Angel,? Jianqiang Ye, Danielle Hickman,* Lindomar Pena,? Gloria Ramirez-Nieto,# Brian Kimble,? and Yonas Araya?
*University of Maryland, College Park;?University of Maryland;?Virginia-Maryland Regional College of Veterinary Medicine;?Virginia-Maryland Regional College of Veterinary Medicine-Maryland Campus and, #Universidad Nacional De Colombia

Terms of use: This research note is distributed under the Creative Commons Attribution 3.0 License.


On June 11, 2009 the World Health Organization (WHO) declared a new H1N1 influenza pandemic. This pandemic strain is as transmissible as seasonal H1N1 and H3N2 influenza A viruses. Major concerns facing this pandemic are whether the new virus will replace, co-circulate and/or reassort with seasonal H1N1 and/or H3N2 human strains. Using the ferret model, we investigated which of these three possibilities were most likely favored. Our studies showed that the current pandemic virus is more transmissible than, and has a biological advantage over, prototypical seasonal H1 or H3 strains.


Introduction

The swine-origin H1N1 pandemic virus was initially linked to human outbreaks in North America in April 2009 and has since spread to over 140 countries in the last five months (http://www.who.int/csr/disease/influenza/en/). The WHO?s decision to proceed to Phase 6, pandemic influenza, was mainly due to the transmissibility, not the morbidity, of the virus. This virus has continued to be isolated during the summer months in North America and spread to the regions of the southern hemisphere where the influenza season is at its peak. Numbers from South American countries indicate this pandemic strain predominates over the seasonal H1 and H3 strains, although all 3 strains appear to circulate. Studies to determine the possibility of reassortment following co-infection of an avian and human virus has been reported [1], as have naturally occurring co-infections in the human population [2],[3],[4] . However, to date there has been no report of co-infection between swine-origin and seasonal human influenza A viruses.
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Full text available following the link below:
<cite cite="http://www.ncbi.nlm.nih.gov/rrn/RRN1011">
Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection</cite>

 

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Re: PLoS Currents Influenza. Fitness of Pandemic H1N1 and Seasonal influenza A viruses during Co-infection: Evidence of competitive advantage of pandemic H1N1 influenza versus seasonal influenza

From the article . . .

Recent reports have speculated on the possibility that the new pandemic H1N1 strain may become more virulent and/or more transmissible if it were to reassort with seasonal influenza strains [8],[9],[10]. Alternatively, it has been postulated that the new H1N1 virus may not be completely adapted to the human population and that additional changes could lead to more virulent and perhaps more transmissible strains [8],[9],[10]. Our studies show that the pandemic Ca/04 virus has a clear biological advantage in replication, transmission, tropism and pathogenesis when compared to both seasonal H1 and H3 representative strains. In addition, co-infection of seasonal and pandemic strains did not result in the rapid selection of reassortant viruses that either improved replication or transmission or exacerbated virulence. Although we must be cautious interpreting studies in the ferret model, it is reasonable to speculate that this prototypical pandemic strain, Ca/04, has all the makings of a virus fully adapted to humans. At present, reassortment may not be particularly favored.