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Rivista trimestrale di Sanità Pubblica Veterinaria edita dall'Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise ‘G. Caporale’

A quarterly journal devoted to veterinary public health, veterinary science and medicine published by the Istituto Zooprofilattico Sperimentale dell’Abruzzo e del Molise ‘G. Caporale’ in Teramo, Italy

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2015 - Volume 51 (3), July-September
Taha Kumosani, Diana M. Ahmadieh, Houssam A. Shaib, Shadi K. Hamadeh, Lina S. Jaber, Steve Harakeh, Archana Iyer, Esam Azhar & Elie K. Barbour  
Oseltamivir activity against avian influenza H9N2 strain with different point mutations in their neuraminidase 217-224
doi: 10.12834/VetIt.013.05.256
The present study has two aims: to optimize the antiviral activity of oseltamivir in chicken embryos against an avian influenza‑H9N2 strain (P0) and to apply the optimized protocol for studying the drug susceptibility of 4 H9N2 mutants (M1, M2, M3, and M4). As for the first aim, oseltamivir antiviral activity was monitored upon its delivery into 9‑day‑old chicken embryo at a concentration of 0.27 mg/100 µl, against 7 doses of the P0 strain, ranging between 1.2 x 10‑5 and 2.0 Hemagglutination (HA) units. Oseltamivir showed its highest efficacy in reduction of viral propagation (95% reduction in HA titer) (P < 0.05), when the inoculum level contained a minimum HA units of 1.2 x 10‑5. For the second aim of this study, the application of the 1.2 x 10‑5 HA units of the virus in inocula for the evaluation of oseltamivir‑antiviral effect against the 4 H9N2 mutants revealed an emergence of a resistant mutant (M1), associated with 2 adjacent point mutations in its neuraminidase (N) amino acid (aa) sequence at positions 46 and 47. The other 3 mutants maintained a variable sensitivity to oseltamivir, resulting in the following reduction in HA titers: M2 (82.9%), M3 (61.5%), and M4 (100.0%). They way in which the point mutations of the neuraminidase sequences affected the susceptibility of H9N2 virus to oseltamivir is still to be determined and deserve further investigations.

Avian Influenza, Embryonic growth, H9N2, Hemagglutination (HA), Mutants, Neuraminidase, Oseltamivir.

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