H5N1 in Cats in Indonesia
Recombinomics Commentary
October 7, 2006
A study conducted by the Indonesian Environment Information Center (PILI) in Yogyakarta found that stray cats had caught the H5N1 virus through contact with infected poultry at traditional markets.
The above comments provide additional evidence implicating an alternative source of H5N1 human infections in Indonesia. Recently, Indonesia summarized the results of poultry tests by a WHO affiliated lab in Australia. Concerns had been voiced in an H5N1 meeting in Jakarta in June because the sequences from the vast majority of human cases on Java did not match the poultry H5N1 collected between 2003 and 2005. Consequently, 91 poultry samples were sent to Australia for virus isolation and sequencing. The samples were from collections between September 2005 and March 2006 and failed to match Java poultry isolates with most of the sequences from patients.
All but one of the human isolates from patients on Java had a novel cleavage site, RESRRKKR, as well as a number of associated changes in all 8 gene segments that readily distinguished the human sequences from the poultry sequence (see green sequences in lower branch). One duck from Indramayu had the novel cleavage site, but that duck isolates had additional changes, including a silent change in the cleavage site, which was found in only a small subset of human isolates. The vast majority of human isolates, including those from Indramayu, failed to match the duck sequences. Two matching sequences were found in chickens in central Sumatra, but the match failure on Java, coupled with the almost universal matching of human sequences, including the first sequence isolate in July 2005 as well as isolates from a wide range of geographical locations, including East Java, suggested human infections were largely due to H5N1 in a reservoir other than poultry.
The only match on Java of the human sequences was from a throat swab of a cat. A/feline/Indonesia/CDC1/2006(H5N1), from Jakarta on January 22, 2006. H5N1 has also been detected in swine in Indonesia, but the swine sequences, including the HA cleavage site, did not match the human sequences. The discovery of more H5N1 in cats in Indonesia raises the possibility that the cats are also in contact with an alternate reservoir.
Sequence data on H5N1 from cats, and “infected poultry in traditional markets”, including those in and around Jakarta, where most of the reported human cases have been located, would help resolve the role of cats in H5N1 transmission.
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