Detection of influenza A viruses from different species by PCR amplification of conserved sequences in the matrix gene

The recently raised awareness of the threat of a new influenza pandemic has stimulated interest in the detection of influenza A viruses in human as we ll as animal secretions. Virus isolation alone is unsatisfactory for this p urpose because of its inherent limited sensitivity and the lack of host cel ls that are universally permissive to all influenza A viruses. Previously d escribed PCR methods are more sensitive but are targeted predominantly at v irus strains currently circulating in humans, since the sequences of the pr imer sets display considerable numbers of mismatches to the sequences of an imal influenza A viruses. Therefore, a new set of primers, based on highly conserved regions of the matrix gene, was designed for single-tube reverse transcription-PCR for the detection of influenza A viruses from multiple sp ecies. This PCR proved to be fully reactive with a panel of 25 genetically diverse virus isolates that were obtained from birds, humans, pigs, horses, and seals and that included all known subtypes of influenza A virus. It wa s not reactive with the 11 other RNA viruses tested. Comparative tests with throat swab samples from humans and fecal and cloacal swab samples from bi rds confirmed that the new PCR is faster and up to 100-fold more sensitive than classical virus isolation procedures.