Quantitative measurement of influenza virus replication using consecutive bronchoalveolar lavage in the lower respiratory tract of a ferret model

The ferret is an established animal model of influenza virus infection. Although viral replication in the upper respiratory tract is usually measured with consecutively collected nasal washes, daily evaluation of viral replication in the lung is limited because a large numbers of ferrets need to be sacrificed at consecutive time points. To overcome this limitation, we performed a virus quantification assay using bronchoalveolar lavage (BAL) fluid. This non-invasive BAL technique allows consecutive quantification of virus replication in the lungs of living ferrets. Our method can be used for the longitudinal evaluation of virus tropism in the lower respiratory tract.

Infl uenza a virus induced apoptosis: Inhibition of DNA laddering & caspase-3 activity by zinc supplementation in cultured HeLa cells.

Background & objectives: The pathogenesis of infl uenza virus infection involves virus replication in epithelial cells of the respiratory tract and the consequent degeneration of infected cells. Infl uenza virus induces cellular degeneration following infection of cultured cells in vitro, and the cytopathic effect (CPE) occurs principally through apoptotic cell death. This study was undertaken to fi nd out the effect of zinc on infl uenza virus induced apoptosis in cultured HeLa cells. Methods: The sub-confl uent monolayer HeLa cells were used to study the effect of zinc on infl uenza virus induced apoptosis. The apoptotic markers viz., caspase-3 activity, phagocytic index, morphological changes, and DNA fragmentation were assayed. Results: When HeLa cells were infected with a cell adapted pathogenic strain of infl uenza A (A/Udorn/ 317/72H3N2) virus, DNA fragmentation was observed in virus infected cells by 24 h post infection and caspase-3 activity was maximum at 4 h post infection after which it reached to plateau. Treatment of cells with 0.1 5mM concentration of zinc till 8 h post infection inhibited DNA fragmentation and also caspase 3 activity was decreased signifi cantly up to 2 h post infection. Interpretation & conclusions: When the infected HeLa cells were incubated with adherent macrophages, effi cient phagocytosis occurred and the release of virus into the culture medium was inhibited. These results suggested that inhibitory effect on infl uenza virus induced apoptotic death of cultured cells can be determined at an early stage of the infection by treatment of zinc.