background : avian influenza virus (aiv) infection is a major cause of bird and human morbidity and mortality. we aimed to evaluate a specific and sensitive multiplex rt-pcr that can simultaneously detect influenza type a viruses and differenti­ate the two most important subtypes of avian influenza viruses h7 and h9 subtypes. methods : a multiplex reverse transcriptase-polymerase chain reaction...

avian influenza is an important disease of poultry with the potential to cause major epidemics resulting in significant economic losses. the presence of avian influenza viruses (aiv) in chickens in iran has not been previously reported. an avian influenza outbreak in broiler, layer and breeder farms occurred during a very hot summer in july 1998. three aiv isolates designated as 101, 102 and 10...

background and aims: avian influenza (ai) h9n2 subtype was first reported to infect turkeys in the united states in 1966 and has been panzootic in europe and asia. the impact of avian influenza caused by h9n2 viruses in iran is now significantly more severe than in previous years. methods: sequence analysis and phylogenetic study of the complete coding region polymerase a (pa) gene of h9n2 subt...

UNLABELLED Zoonotic avian influenza virus infections may lead to epidemics or pandemics. The 1918 pandemic influenza virus has an avian influenza virus-like genome, and its H1 hemagglutinin was identified as a key mammalian virulence factor. A chimeric 1918 virus expressing a contemporary avian H1 hemagglutinin, however, displayed murine pathogenicity indistinguishable from that of the 1918 vir...

Influenza A viruses possesses two virion surface glycoproteins including haemagglutinin (HA) and neuraminidase (NA). The NA plays an important role in viral replication and promotes virus release from infected cells and facilitates virus spread throughout the body. To find out any genomic changes that might be occurred on NA gene of avian influenza circulating viruses, we have genetically analy...

Transmission of avian influenza viruses from bird to human is a rare event even though avian influenza viruses infect the ciliated epithelium of human airways in vitro and ex vivo. Using an in vitro model of human ciliated airway epithelium (HAE), we demonstrate that while human and avian influenza viruses efficiently infect at temperatures of the human distal airways (37 degrees C), avian, but...

Avian influenza viruses replicate in a variety of mammals and birds, yet hemagglutination inhibition tests show that postinfection sera from these animals (e.g., ferrets and ducks) have insignificant levels of antibodies (Hinshaw et al., Infect. Immun. 34:354-361, 1981). This suggested that avian influenza viruses, in contrast to mammalian viruses, may not induce a significant humoral response....

The recent human infections caused by H5N1, H9N2, and H7N7 avian influenza viruses highlighted the continuous threat of new pathogenic influenza viruses emerging from a natural reservoir in birds. It is generally believed that replication of avian influenza viruses in humans is restricted by a poor fit of these viruses to cellular receptors and extracellular inhibitors in the human respiratory ...

Recently, three novel avian-origin swine influenza viruses (SIVs) were first isolated from pigs in Guangdong Province, southern China, yet little is known about the seroprevalence of avian influenza viruses among pigs in southern China. Here, we report for the first time the seroprevalence of avian H3, H4, and H6 influenza viruses in swine populations and the lack of seroepidemiological evidenc...