نتایج جستجو برای: avian viruses
تعداد نتایج: 134523 فیلتر نتایج به سال:
Human influenza viruses manage to cause epidemics almost every year. The circulating viruses change their surface glycoproteins by accumulating mutations (antigenic drift) which results in variant viruses of the same subtype that are able to evade the immune pressure in the population. Every now and then, a completely new subtype of influenza A virus is introduced in the human population, which...
Swine influenza viruses possessing avian genes were first detected in Europe in 1979 (Scholtissek et al., 1983, Virology, 129, 521-523) and continue to circulate in pigs in that region of the world. To characterize the molecular epidemiology of swine influenza viruses currently circulating in Europe, we used dot-blot hybridization and sequence analysis to determine the origin of the genes encod...
Transfer of influenza A viruses from animal hosts to man may lead to the emergence of new human pandemic strains. The early detection and identification of such events are therefore paramount in the surveillance of influenza viruses. To detect and partially characterize influenza A viruses from different animal species, a combined reverse transcription (RT)-PCR heteroduplex mobility assay (HMA)...
BACKGROUND Influenza viruses bind and infect respiratory epithelial cells through sialic acid on cell surface. Differential preference to sialic acid types contributes to host- and tissue-tropism of avian and seasonal influenza viruses. Although the highly pathogenic avian influenza virus H5N1 can infect and cause severe diseases in humans, it is not efficient in infecting human upper respirato...
West Nile virus (WNV) and St. Louis encephalitis (SLEV) virus are enzootically maintained in North America in cycles involving the same mosquito vectors and similar avian hosts. However, these viruses exhibit dissimilar viremia and virulence phenotypes in birds: WNV is associated with high magnitude viremias that can result in mortality in certain species such as American crows (AMCRs, Corvus b...
sixteen avian influenza (ai) h9n2 viruses were isolated from disease outbreaks in different parts of iranduring (1998–2001). these ai isolates were used for pathogenicity, haemagglutinin (ha) gene variation andphylogenetic analysis. results in both pathogenicity tests and ha gene cleavage site sequence detectionrepresented a non-highly pathogenic feature for all iranian ai isolates studied. the...
Novel influenza viruses of the H7N9 subtype have infected 33 and killed nine people in China as of 10 April 2013. Their haemagglutinin (HA) and neuraminidase genes probably originated from Eurasian avian influenza viruses; the remaining genes are closely related to avian H9N2 influenza viruses. Several characteristic amino acid changes in HA and the PB2 RNA polymerase subunit probably facilitat...
BACKGROUND: The H9N2 subtype of avian influenzaviruses (AIVs) has been isolated in multiple avian species inmany European, Asian, African and American countries. Sincethe first outbreak of H9N2 virus in Iran in 1998, this virus haswidely circulated throughout the country, resulting in majoreconomic losses in chicken flocks. Several amino acids in thevirus ribonucleoprotein (RNP) complex includi...
Changes in the hemagglutinin of H5N1 viruses during human infection – Influence on receptor binding☆
As avian influenza A(H5N1) viruses continue to circulate in Asia and Africa, global concerns of an imminent pandemic persist. Recent experimental studies suggest that efficient transmission between humans of current H5N1 viruses only requires a few genetic changes. An essential step is alteration of the virus hemagglutinin from preferential binding to avian receptors for the recognition of huma...
The adaptation of H5N1 avian influenza viruses to human poses a great threat to public health. Previous studies indicate the adaptive mutations in viral polymerase of avian influenza viruses are major contributors in overcoming the host species barrier, with the majority of mammalian adaptive mutations occurring in the PB2 protein. However, the adaptive mutations in the PA protein of the H5N1 a...
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