|BERTRAN, KATERI - U.S. DEPARTMENT OF AGRICULTURE (USDA)|
Submitted to: International Symposium on Avian Influenza
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2015
Publication Date: 4/12/2015
Citation: Swayne, D.E., Bertran, K., Kapczynski, D.R., Pantin Jackwood, M.J., Spackman, E., Suarez, D.L. 2015. Reduced experimental infectivity and transmissibility of intercontinental H5 (H5N8 and H5N2) compared to Eurasian H5N1 highly pathogenic avian influenza viruses for chickens, turkeys, and Japanese quail [abstract]. 9th International Symposium on Avian Influenza, Athens, Georgia. p. 56.
Technical Abstract: H5N1 high pathogenicity avian influenza (HPAI) virus (HPAIV) emerged in 1996 in Guangdong China and has since spread to infect and cause deaths in wild birds, poultry and humans in over 63 countries in Asia, Europe and Africa; and more recently a reassortant H5N8 clade 220.127.116.11 HPAI virus has spread to Europe and North America with further reassortment with North America low pathogenicity avian influenza virus genes. Studies to understand the infectivity and transmissibility of an H5N8 and H5N2 clade 18.104.22.168 HPAI viruses in chickens, turkeys and Japanese quail were undertaken. Chickens and Japanese quail were frequently listless and had ruffled feathers before death, but a few had neurological signs. Pancreatic necrosis, splenomegaly, renomegaly and petechial hemorrhages on myocardium were the most common lesions in birds that died. However, some chickens also had cyanosis of combs and wattles. Neurological signs were the primary presentation of disease in turkeys. The mean death time in all species was late (3-9 days post exposure) when compared to H5N1 HPAIV (2-3 days). Infection lead to death as survivors lacked H5 hemagglutination inhibiting antibodies. However, neither virus appeared to be well adapted to chickens or turkeys and required a dose of 6log10 50% egg infectious doses (EID50) per bird to achieve 50% infection and did not transmit to contact exposure birds. Quail were slightly more susceptible with a 50% infectious dose of 4 log10 EID50 per bird for each isolate. These results suggest the intercontinental H5N8 and H5N2 HPAIV have reduced virulence and transmissibility for gallinaceous host compared to historical H5N1 HPAIV.