Risk Assessment of H2N2 Influenza Viruses from the Avian Reservoir

[tetano]

J Virol. 2013 Nov 13. [Epub ahead of print]
Risk Assessment of H2N2 Influenza Viruses from the Avian Reservoir.
Jones JC, Baranovich T, Marathe BM, Danner AF, Seiler JP, Franks J, Govorkova EA, Krauss S, Webster RG.
Source

Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN, USA.
Abstract

H2N2 influenza A viruses were the cause of the 1957-1958 pandemic. Historical evidence demonstrates they arose from avian virus ancestors, and while the H2N2 subtype has disappeared from humans, it persists in wild and domestic birds. Re-emergence of H2N2 in humans is a significant threat due to the absence of humoral immunity in individuals under the age of 50. Thus, examination of these viruses, particularly those from the avian reservoir, must be addressed through surveillance, characterization, and antiviral testing. The data presented here are a risk assessment of 22 avian H2N2 viruses isolated from wild and domestic birds over 6 decades. Our data showed that they have a low rate of genetic and antigenic evolution and remained similar to isolates circulating near the time of the pandemic. Most isolates replicated in mice and human bronchial epithelial cells, but replication in swine tissues was low or absent. Multiple isolates replicated in ferrets, and 3 viruses were transmitted to direct-contact cagemates. Markers of mammalian adaptation in HA and PB2 proteins were absent from all isolates, and they retained a preference for avian-like α2-3 linked sialic acid receptors. Most isolates remained antigenically similar to pandemic A/Singapore/1/57 (H2N2) virus, suggesting they could be controlled by the pandemic vaccine candidate. All viruses were susceptible to neuraminidase inhibitors and adamantanes. Nonetheless, the sustained pathogenicity of avian H2N2 viruses in multiple mammalian models elevates their risk potential for human infections and stresses the need for continual surveillance as a component of pre-pandemic planning.

PMID:
24227848
[PubMed - as supplied by publisher]

http://www.ncbi.nlm.nih.gov/pubmed/24227848

 

[Shiloh]

Re: Risk Assessment of H2N2 Influenza Viruses from the Avian Reservoir

Source: http://newswise.com/articles/1950s-.../articles/list&category=science&page=1&search[status]=3&search[sort]=date+desc&search[section]=20&search[has_multimedia]=

1950s Pandemic Influenza Virus Remains a Health Threat, Particularly to Those Under 50
St. Jude Children?s Research Hospital scientists report that avian H2N2 influenza A viruses related to 1957-1958 pandemic infect human cells and spread among ferrets; may aid identification of emerging threats
Released: 12/3/2013 12:00 PM EST
Source Newsroom: St. Jude Children's Research Hospital


Newswise ? (MEMPHIS, TENN. ? December 3, 2013) St. Jude Children?s Research Hospital scientists have evidence that descendants of the H2N2 avian influenza A virus that killed millions worldwide in the 1950s still pose a threat to human health, particularly to those under 50. The research has been published in an advance online edition of the Journal of Virology.

The study included 22 H2N2 avian viruses collected from domestic poultry and wild aquatic birds between 1961 and 2008, making it the most comprehensive analysis yet of avian H2N2 viruses.

Researchers reported the viruses could infect human respiratory cells. Several strains also infected and spread among ferrets, which are susceptible to the same flu viruses as humans. Based on those and other indicators, one virus was classified as posing a high risk for triggering a pandemic...

 

[Giuseppe]

Re: Risk Assessment of H2N2 Influenza Viruses from the Avian Reservoir

It would be interesting to see how the old H2N2 was displaced by the reassortant H3N2 and whether the N2 component would play a role in cross-reactive immunity in humans.