RESUMO
No evidence of exposure to canine distemper virus (CDV) was detected in 70 samples corresponding to 58 wild-trapped Darwin's foxes (Lycalopex fulvipes) in Chile. Given its current endangered status and it being immunologically naïve, in the event of a CDV spillover from dogs to foxes, high population mortality is expected.
Assuntos
Vírus da Cinomose Canina/isolamento & purificação , Raposas/virologia , Animais , Anticorpos Antivirais/sangue , Vigilância da PopulaçãoRESUMO
Two different wild duck species common in Chile and neighboring countries, Chiloe wigeon (Anas sibilatrix) and cinnamon teal (Anas cyanoptera), were intranasally inoculated with 10(6) mean embryo infective dose (EID50) of the H7N3 low pathogenicity (LP) avian influenza virus (AIV) (A/chicken/Chile/176822/02) or high pathogenicity (HP) AIV (A/chicken/Chile/ 184240-1/02), in order to study the infectivity and pathobiology of these viruses. None of the virus-inoculated ducks had clinical signs or died, but most seroconverted by 14 days postinoculation (DPI), indicating a productive virus infection. Both LPAIV and HPAIV were isolated from oral swabs from two of six Chiloe wigeons and from oral and/or cloacal swabs from all five of the cinnamon teal at 2 DPI. Both LPAIV and HPAIV were efficiently transmitted to cinnamon teal contacts but not to Chiloe wigeon contacts. This study demonstrates that the cinnamon teal and Chiloe wigeons were susceptible to infection with both Chilean H7N3 LPAIV and HPAIV, but only the cinnamon teal showed contact transmission of the virus between birds, suggesting that the cinnamon teal has the potential to be a reservoir for these viruses, especially the LPAIV, as was demonstrated in 2001 with isolation of a genetically related H7N3 LPAIV strain in a cinnamon teal in Bolivia. However, the definitive source of the H7N3 Chilean LPAIV still remains unknown.
Assuntos
Patos , Vírus da Influenza A Subtipo H7N3/genética , Vírus da Influenza A Subtipo H7N3/patogenicidade , Influenza Aviária/virologia , Animais , Anticorpos Antivirais/análise , Cloaca/virologia , Suscetibilidade a Doenças/veterinária , Ensaio de Imunoadsorção Enzimática , Vírus da Influenza A Subtipo H7N3/classificação , Vírus da Influenza A Subtipo H7N3/isolamento & purificação , Influenza Aviária/imunologia , Influenza Aviária/patologia , Influenza Aviária/transmissão , Doenças Pulmonares Intersticiais/fisiopatologia , Doenças Pulmonares Intersticiais/veterinária , Orofaringe/virologia , Sistema Respiratório/virologia , Especificidade da EspécieRESUMO
Influenza A viruses occur worldwide in wild birds and are occasionally associated with outbreaks in commercial chickens and turkeys. However, avian influenza viruses have not been isolated from wild birds or poultry in South America. A recent outbreak in chickens of H7N3 low pathogenic avian influenza (LPAI) occurred in Chile. One month later, after a sudden increase in deaths, H7N3 highly pathogenic avian influenza (HPAI) virus was isolated. Sequence analysis of all eight genes of the LPAI virus and the HPAI viruses showed minor differences between the viruses except at the hemagglutinin (HA) cleavage site. The LPAI virus had a cleavage site similar to other low pathogenic H7 viruses, but the HPAI isolates had a 30-nucleotide insert. The insertion likely occurred by recombination between the HA and nucleoprotein genes of the LPAI virus, resulting in a virulence shift. Sequence comparison of all eight gene segments showed the Chilean viruses were also distinct from all other avian influenza viruses and represent a distinct South American clade.