Experimental Pandemic (H1N1) 2009 Virus Infection of Cats

DHHS/CDC Center For Infectious Diseases
Volume 16, Number 11–November 2010
Judith M.A. van den Brand, Koert J. Stittelaar, Geert van Amerongen, Marco W.G. van de Bildt, Lonneke M.E. Leijten, Thijs Kuiken, and Albert D.M.E. Osterhaus Comments to Author
Author affiliations: Erasmus Medical Centre, Rotterdam, the Netherlands (J.M.A. van den Brand, K.J. Stittelaaar, G. van Amerongen, M.W.G. van de Bildt, L.M.E. Leijten, T. Kuiken, A.D.M.E. Osterhaus); and ViroClinics Biosciences BV, Rotterdam (K.J. Stittelaar, G. van Amerongen, A.D.M.E. Osterhaus)

Soon after pandemic (H1N1) 2009 virus emerged in North America, infections in domestic cats were reported (1,2). Infection with highly pathogenic avian influenza (HPAI) virus (H5N1) leads to severe and often fatal diffuse alveolar damage and systemic virus spread in cats (3–5). In contrast, seasonal human influenza viruses do not cause disease in cats (6). To elucidate the pathogenesis of pandemic (H1N1) 2009 virus infection in cats, we studied 8 laboratory cats intratracheally infected with this virus.

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Conclusions

Intratracheal infection of domestic cats with pandemic (H1N1) 2009 virus resulted in mild-to-moderate clinical signs and virus replication throughout the respiratory tract, which caused diffuse alveolar damage. The pathogenesis in the respiratory tract in cats was similar to that occurring in humans, macaques, and ferrets (7,11–13). Seroconversion of sentinel cats indicated cat-to-cat transmission.

Unlike infection with seasonal human influenza viruses, infection with pandemic (H1N1) 2009 virus causes respiratory disease in cats. To compare infections with these viruses, we used our unpublished data for cats intratracheally infected with 105.0 TCID50 of HPAI virus (H5N1) (A/Indonesia/5/05) at 4 dpi and 7 dpi (4) and for sham-infected cats. Histopathologic and immunohistochemical findings in lungs of cats infected with these viruses coincided, which indicated a similar pathogenetic process and increased severity in cats infected with HPAI virus (H5N1). However, in contrast to HPAI virus (H5N1), pandemic (H1N1) 2009 virus does not cause extrapulmonary lesions in infected cats. Our data show that pandemic (H1N1) 2009 virus may cause respiratory disease in cats and that human-to-cat transmission is the most likely route of infection.