AbstractsBiology & Animal Science

Rokshana Parvin Molecular epidemiology and biological properties of avian influenza viruses of subtype H5N1 and H9N2 Institute of Virology Submitted in November 2014 Pages 106, Figures 7, Table 1, References 339, Publications 4 Keywords: Avian Influenza Virus, H5N1, H9N2, Reassortment, Mutation, Replication and Growth kinetics Introduction Avian influenza viruses (AIVs) are the major cause of significant disease outbreaks with high morbidity and mortality worldwide in domestic birds resulting in great economic losses. Especially the subtypes of highly pathogenic avian influenza viruses (HPAIV) H5N1 and low pathogenic avian influenza viruses (LPAIV) H9N2 became the most prevalent AIVs in poultry causing regular disease outbreaks in many countries of Asia, the Middle East and Europe and are still ongoing events. Therefore, continues monitoring, surveillance and characterization of the circulating viruses are of high priority. Objectives The current study was designed for three main objectives; i) Molecular epidemiology of the HPAIV H5N1 in migratory birds in Bangladesh, ii) Molecular characterization of the AIV subtype H9N2 and iii) Biological properties of the AIV subtype H9N2. Materials and methods In first the part of the investigations, two HPAIV H5N1 strains were confirmed from 205 pools of fecal surveillance samples in Bangladesh. The two isolated H5N1 viruses were characterized by genome amplification and sequence analysis of the all eight genome segments. In the second part of the investigations, a confirmed AIV H9N2 from a retrospective analysis derived from a poultry farm in Bangladesh was characterized. Furthermore, three AI-H9N2 viruses were isolated and characterized from a commercial broiler and broiler breeder flock with clinical respiratory manifestations in Egypt. Full length genome amplification, cloning, sequencing and comprehensive phylogenetic analyses were performed for all eight genome segments. In the final part of the study, four selected Eurasian lineage H9N2 viruses - three G1 sub-lineages H9N2 and one European wild bird H9N2 virus - were propagated in embryonated chicken eggs (ECE) and Madin-Darby canine kidney epithelial cell culture systems. The ECE-grown and cell culture-grown viruses were monitored for replication kinetics based on tissue culture infectious dose (TCID50), hemagglutination assay (HA) and quantitative real time RT-PCR (qRT-PCR). The cellular morphology after infections was analyzed by immunofluorescence assay and cellular ELISA was performed to screen the sensitivity of the viruses to amantadine. Results The two newly isolated HPAIV H5N1 strains from migratory birds belonged to clade 2.3.2.1 and clustered together with other recently isolated viruses in Bangladesh derived from ducks, chickens, quails and crow. The amino acid sequences were also genetically similar although, some unique amino acid substitutions were observed. These substitutions were not related to the known conserved region of the molecular determinants of the virus. The phylogenetic analyses of…