title: Variability of tropism and replicative capacity of two naturally occurring influenza A H9N2 viruses in cell cultures from different tissues.
abstract: Studies carried out on cell permissivity are of great interest to understand virus replication and pathogenicity. We described the results of a comparative analysis of replication efficiency of two naturally occurring influenza A H9N2 variants isolated from poultry and wild birds, differing by only two substitutions Q226L and T384N, in the receptor-binding site of haemagglutinin 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 titres up to 10(9) TCID50/ml whereas small intestine culture was highly susceptible to the TUN51Q226T384 virus reaching a titre 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 culture types with maximum titres 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 a reverse genetics approach and the examination of cellular protease expression in chicken tissues. This would lead to a more complete understanding of the tropism of low-pathogenic Influenza A viruses.
authors.affiliation: a Laboratory of Epidemiology and Veterinary Microbiology , Institute Pasteur of Tunis, University Tunis El Manar , Tunis- Belvédère , Tunisia.
authors.forename: Wafa
authors.initials: W
authors.lastname: Tombari
authors.affiliation: a Laboratory of Epidemiology and Veterinary Microbiology , Institute Pasteur of Tunis, University Tunis El Manar , Tunis- Belvédère , Tunisia.
authors.forename: Imen
authors.initials: I
authors.lastname: ElBehi
authors.affiliation: a Laboratory of Epidemiology and Veterinary Microbiology , Institute Pasteur of Tunis, University Tunis El Manar , Tunis- Belvédère , Tunisia.
authors.forename: Faten
authors.initials: F
authors.lastname: Amouna
authors.affiliation: a Laboratory of Epidemiology and Veterinary Microbiology , Institute Pasteur of Tunis, University Tunis El Manar , Tunis- Belvédère , Tunisia.
authors.forename: Abdeljelil
authors.initials: A
authors.lastname: Ghram
mesh_terms: D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000818:Animals; D001717:Birds; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000821:virology*; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D053127:Influenza A Virus, H9N2 Subtype / Q000472:pathogenicity / Q000502:physiology*; D005585:Influenza in Birds / Q000821:virology*; D009154:Mutation; D009439:Neuraminidase / Q000235:genetics; D013047:Specific Pathogen-Free Organisms; D018523:Tropism; D014779:Virus Replication
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D009439:Neuraminidase
keywords: Culture cells; cell tropism; kinetic replication; low pathogenicity influenza virus; virus host range