1.Molecular Characterization of Avian Infectious Bronchitis Virus Isolated in Malaysia during 2014-2016
Leow, B.L. ; Syamsiah Aini, S ; Faizul Fikri, M.Y ; Muhammad Redzwan, S. ; Khoo, C.K ; Ong, G.H. ; Basirah, M.A ; Norazura, B. ; Mazaitul, Z. ; Mohd Khairil, A. ; Mohd. Jihan, R ; Sohayati, A.R ; Chandrawathani, P.
Tropical Biomedicine 2018;35(4):1092-1106
Avian Infectious Bronchitis (IB) is a highly contagious disease which can cause
huge economic losses to the poultry industry. Forty five IB viruses (IBV) were isolated
from poultry in Malaysia during 2014-2016. Phylogenetic analysis of the spike glycoprotein
1 (S1) gene revealed that all isolates were clustered into five distinct groups. The
predominant type of IBV isolated was QX strains (47%), second was 4/91 type (27%),
followed by Malaysian strain MH5365/95 (13%), Massachusetts type (11%) and finally
Taiwanese strains (2%). Four types of S1 protein cleavage recognition motifs were found
among the isolates which includes HRRRR, RRSRR, RRFRR and RRVRR. To our knowledge,
this is the first report describing the motif RRVRR and are unique to Malaysian strains. Six
IBVs were grouped in Malaysian MH5365/95 strains. Among these, one isolate was different
from others where it only shared 82% identity with MH5365/95 and to others. It formed its
own branch in the Malaysian cluster suggesting it may be a variant unique to Malaysia.
Alignment analysis of the S1 amino acid sequences indicated that point mutations, insertions
and deletions contribute to the divergence of IB variants. This study indicated at least five
groups of IBV are circulating in Malaysia with most of the isolates belonged to QX strains.
As new IBV variants continue to emerge, further study need to be carried out to determine
whether the current available vaccine is able to give protection against the circulating
virus.
Result Analysis
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