Variability of tropisms and replicative capacities of naturally occurring viruses of H9N2 influenza A virus in different tissues culture.

We described the results of a comparative analysis of replication efficiency of two naturally occurring H9N2 variants isolated from poultry and wild birds, differing by only two substitutions Q226L and T384N, in the receptor binding site of HA and the 380 loop region of NA proteins, respectively. Considering the overall growth of both viruses, lung cultures ensured the most efficient growth of TUN12L226N384 strain with titers up to 10(9) TCID50/ml. Whereas, small intestine culture was highly susceptible to the TUN51Q226T384 virus reaching a titer of 10(6) TCID50/ml. The lowest replication was shown in liver cells. The addition of trypsin was essential for the replication of either virus in primary fibroblasts, but it had a marginal positive effect on virus replication in the four other cultures types with maximum titers of 10(8) TCID50/ml. This means that in chicken, the proteolytic activation of the H9N2 viruses with the cleavage motif RSSR may be mediated by other endoproteases than trypsin. Further investigations should concentrate on the production of the appropriate set of viruses by reverse genetics approach and the examination of cellular protease expression in chicken tissues. This would lead to a more complete understanding of the LPAIV tropism. PMID: 26813086 [PubMed - as supplied by publisher]
Source: Avian Pathology - Category: Pathology Authors: Tags: Avian Pathol Source Type: research

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