The pathogenicity and transmission of live bird market H2N2 avian influenza viruses in chickens, Pekin ducks, and guinea fowl

Authors: MO, JONGESO - Orise Fellow; YOUK, SONGSU - Orise Fellow; Pantin Jackwood, Mary; Suarez, David; LEE, DONG-HUN - University Of Connecticut; KILLIAN, MARY LEA - Animal And Plant Health Inspection Service (APHIS); BERGESON, NICHOLE - Animal And Plant Health Inspection Service (APHIS); Spackman, Erica

Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2021
Publication Date: 7/13/2021
Citation: Mo, J., Youk, S., Pantin Jackwood, M.J., Suarez, D.L., Lee, D., Killian, M., Bergeson, N.H., Spackman, E. 2021. The pathogenicity and transmission of live bird market H2N2 avian influenza viruses in chickens, Pekin ducks, and guinea fowl. Veterinary Microbiology. 260:109180. https://doi.org/10.1016/j.vetmic.2021.109180.
DOI: https://doi.org/10.1016/j.vetmic.2021.109180

Interpretive Summary: Avian influenza viruses naturally infect waterfowl and generally do not get sick. Therefore ducks can carry the virus and transmit it to other species, such as chickens and guinea fowl that are common in the live bird markets in the Northeast U.S. Some of these strains don't cause disease in chickens or guinea fowl either, therefore numerous avian species can serve as asymptomatic sources of flu for humans and domestic mammals in the live bird markets. The non-virulent (i.e., low pathogenic) form of avian influenza, is sporadically found in the live bird markets, but one group called H2N2 has been found fairly consistently over the past few years. In order to determine if the virus has become adapted to the live bird market eco-system (i.e., the most common species found there), a study was completed to determine the dose needed to infect chickens, ducks and guinea fowl and to correlate it with genetic changes. None of the viruses caused any disease in any of the birds. Importantly, a newer virus with a specific genetic mutation that results in a shortened coat protein on the virus was able to infect the birds at a lower does, suggesting that the mutation is associated with better adaptation to these species.

Technical Abstract: H2N2 subtype low pathogenic avian influenza viruses (LPAIVs) have persisted in live bird markets (LBMs) in the Northeastern United States since 2014. Although unrelated to the 1957 pandemic H2N2 lineage, there is concern that the virus could have animal and public health consequences because of high contact with humans and numerous species in the LBM system. The pathogenicity, infectivity, and transmissibility of six LBM H2N2 viruses isolated from three avian species in LBMs were examined in chickens. Two of these isolates were also tested in Pekin ducks and guinea fowl. Full genome sequence was obtained from all 6 isolates and evaluated for genetic markers for host adaptation and pathogenicity in poultry. Clinical signs were not observed in any host with any of the isolates, however one recent isolate was shed at higher titers than the other isolates and had the lowest bird infectious dose of all the isolates tested in all three species This isolate, A/chicken/NY/19-012787-1/2019, was also the only isolate with a deletion in the stalk region of the neuraminidase protein (NA). This supports the theory that the NA stalk deletion is evidence of adaptation to gallinaceous poultry.