Replication of avian influenza A viruses in mammals.

AUTOR(ES)

Hinshaw, V S

RESUMO

The recent appearance of an avian influenza A virus in seals suggests that viruses are transmitted from birds to mammals in nature. To examine this possibility, avian viruses of different antigenic subtypes were evaluated for their ability to replicate in three mammals-pigs, ferrets, and cats. In each of these mammals, avian strains replicated to high titers in the respiratory tract (10(5) to 10(7) 50% egg infective doses per ml of nasal wash), with peak titers at 2 to 4 days post-inoculation, similar to the pattern of human and other mammalian viruses in these animals. Most avian strains were recovered for 5 to 9 days post-inoculation. One avian H1N1 virus initially replicated poorly in pigs, but was adapted to this host and even transmitted to other pigs. Replication of the avian viruses occurred in the respiratory tracts of mammals, whereas, in birds, they replicate in the intestinal tract as well. The infected mammals had no significant disease signs and produced low levels of humoral antibodies; however, challenge experiments in ferrets indicated that they were immune. These studies suggest that influenza A viruses currently circulating in avian species represent a source of viruses capable of infecting mammals, thereby contributing to the influenza A antigenic pool from which new pandemic strains may originate.

Documentos Relacionados

• Neuraminidase hemadsorption activity, conserved in avian influenza A viruses, does not influence viral replication in ducks.
• Residue 627 of PB2 Is a Determinant of Cold Sensitivity in RNA Replication of Avian Influenza Viruses
• Efficacy of Zanamivir against Avian Influenza A Viruses That Possess Genes Encoding H5N1 Internal Proteins and Are Pathogenic in Mammals
• Virulence of Avian Influenza A Viruses for Squirrel Monkeys
• The histology of epiphyseal union in mammals.