Relationship between pathogenicity and sequences of H6N1 avian influenza viruses and vertical transmission test
Date Issued
2004
Date
2004
Author(s)
Hsu, Chieh-Ning
DOI
zh-TW
Abstract
Abstract
The virulence of avian influenza virus is polygenic, and the hemagglutinin (HA) glycoprotein plays as a determinant of pathogenicity. In Taiwan H6 subtype AIV is the most occurrence subtype. The purpose of this study was to recognize the relationship between pathogenenicity and sequences of H6N1 avian influenza viruses in Taiwan. By 3 rounds of limiting dilution and plaque purification, a H6N1 low pathogenetic AIV strain, 2838DN, was cloned from a field isolate, 2838/00. By contact infection, a more virulent strain named 2838K was obtained from the kidneys of the dead chicks. The IVPI of 2838DN and 2838K was 0.16 and 0.72, respectively. Cytopathic effect also revealed the increased virulence of 2838K compared to 2838DN strain. We have cloned the whole genome of eight genes of AIV 2838DN and 2838K successfully. By comparing the amino acid of HA, replacement of Alanine by Threonine at the –5th and glutamic acid by lysine at the 304th may increase the virulence. 12 amino acid deletion in the stalk of NA gene was found in both clones. There are 6 amino acid mutations in HA gene, 1 in NA and NS gene, 2 in PA and PB1 gene, 5 in PB2 gene, 7 in NP gene of 2838K compared to 2838DN strain. Although horizontal transmission of AI viruses commonly occurs, proof of vertical transmission is lacking and information concerning the potential for egg-borne transmission of the virus is limited. To clearify whether H6N1 AIV vertical transmission vertically transmit or not. The representative virus strain 2838K as 0.5-2.5 EID50/0.1ml was inoculated into the allantoic cavity of twenty 9-11 day-old SPF embryonating chicken eggs per test and 8 repeats had been conducted. Among 152 inoculated SPF embryonating eggs, we were unable to isolate AIV from 91 chicks. In the other way, by intranasal inoculation of 2838K to 9 laying hens, we detected AIV isolated among 6 hatchings from inoculated hens successfully.
Subjects
禽流感
基因序列
avian influenza virus
sequence of AI 8 gene
Type
thesis
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