Sea otters test positive for H1N1 antibodies
Federal researchers have found antibodies to the 2009 H1N1 (pH1N1) flu virus in almost three fourths of sea otters they tested that were from off the coast of Washington state, according to a letter today in Emerging Infectious Diseases.
Researchers from the Centers for Disease Control and Prevention and US Geological Survey collected samples from 30 sea otters captured in 2011 and found that 22 (73%) had hemagglutination inhibition antibody titers of 40 or higher against the pH1N1 virus. They also found that the serum from 21 otters (70%) had detectable Immunoglobulin G (higher than 200) for recombinant hemagglutinin (HA) of the A/Texas/05/2009 pH1N1 strain.
The authors write, "Although we cannot exclude the possibility that sea otters were infected with classical swine influenza A(H1N1) virus, which shares high HA genetic and antigenic similarity with pH1N1 virus, our serologic evidence is consistent with isolation of pH1N1 virus from northern elephant seals [off the California coast in 2010]. Therefore, we conclude that these sea otters were infected with pH1N1 virus."
They add, "Our results show that sea otters are susceptible to infection with influenza A virus and highlight the complex nature of interspecies transmission of influenza viruses in the marine environment."
They said the source of the virus remains unknown.
Mar 31 Emerg Infect Dis letter
Study: 'Universal' vaccine protects mice against H7N9, other strains
A "universal" influenza vaccine containing H5N1 proteins but designed to combat diverse flu strains protected mice against H7N9, H3N2, pH1N1, and H7N7, according to a study by Hong Kong researchers published yesterday in the Proceedings of the National Academy of Sciences.
The vaccine, made by Wyeth, uses a live vaccinia (cowpox) virus that expresses multiple H5N1 viral proteins (HA, neuraminidase, matrix protein 1 [M1], M2, and nucleoprotein) as well as an immune-boosting adjuvant called IL-15. It has already proved to be protective for mice against various H5 strains, the authors write.
In the current study, the vaccine increased survival in the animals compared with those who didn't receive it and significantly reduced viral loads in the mice's lungs against the most recent human H7N9 strain, seasonal H3N2, pH1N1, and a highly pathogenic H7N7 avian flu virus. The vaccine induced T-cell immune responses that recognized different flu viruses, and those responses were augmented in the presence of a challenge virus, the researchers said.
They conclude, "This study illustrates the potential utility of our multivalent Wyeth/IL-15/5Flu as a universal influenza vaccine with a correlate of protective immunity that is independent of neutralizing antibodies."
Mar 31 Proc Natl Acad Sci abstract