1.Molecular survey and sequence analysis of Anaplasma spp. in cattle and ticks in a Malaysian farm
Tay, S.T. ; Koh, F.X. ; Kho, K.L. ; Ong, B.L.
Tropical Biomedicine 2014;31(4):769-776
This study was conducted to determine the occurrence of Anaplasma spp. in the
blood samples of cattle, goats, deer and ticks in a Malaysian farm. Using polymerase chain
reaction (PCR) and sequencing approach, Anaplasma spp. was detected from 81(84.4%) of
96 cattle blood samples. All blood samples from 23 goats and 22 deer tested were negative.
Based on the analysis of the Anaplasma partial 16S ribosomal RNA gene, four sequence types
(genotypes 1 to 4) were identified in this study. Genotypes 1-3 showed high sequence similarity
to those of Anaplasma platys/ Anaplasma phagocytophilum, whilst genotype 4 was identical
to those of Anaplasma marginale/ Anaplasma centrale/ Anaplasma ovis. Anaplasma DNA
was detected from six (5.5%) of 109 ticks which were identified as Rhipicephalus (formely
known as Boophilus) microplus ticks collected from the cattle. This study reported for the
first time the detection of four Anaplasma sequence types circulating in the cattle population
in a farm in Malaysia. The detection of Anaplasma DNA in R. microplus ticks in this study
provides evidence that the ticks are one of the potential vectors for transmission of
anaplasmosis in the cattle.
2.Molecular characterisation of hemagglutinin and neuraminidase genes of the first highly pathogenic Avian Influenza H5N1 2.3.2.1c virus isolated from Sabah, Malaysia
Leow, B.L. ; Syamsiah Aini, S. ; Faizul Fikri, M.Y. ; Muhammad Redzwan, S. ; Ong, G.H. ; Faizah Hanim, M.S.
Tropical Biomedicine 2022;39(No.2):160-169
Highly Pathogenic Avian Influenza (HPAI) is a highly contagious disease in poultry. The outbreaks can
lead to flock mortality up to 100% in two to three days. In July 2018, high mortality in a commercial
layer farm in Kauluan village, Sabah was reported. Samples were sent to Veterinary Research Institute
Ipoh for diagnosis. Virus isolation and molecular detection is carried out simultaneously. The causative
agent was then identified as AI H5N1 virus by real time reverse transcription-polymerase chain reaction
(RT-PCR). The virus was then subjected for further nucleotide sequencing of full length hemagglutinin
(HA) and neuraminidase (NA) gene. The PQRERRRKR/GLF motif at the HA cleavage site indicated that the
isolate was of HPAI virus. Phylogenetic analysis of the HA gene showed that the isolate was belonged to
the clade 2.3.2.1c virus. In the HA gene, besides the S133A substitution, the virus possesses conserved
amino acid at most of the avian receptor binding sites including the glutamine (Q) and glycine (G) at
position 222 and 224 respectively, indicating that the virus retains the avian-type receptor binding
preference. As such, the zoonotic potential of the virus was relatively low. On the other hand, though
the N154D and T156A substitution were detected in the same gene, the pandemic potential of this
Sabah 2.3.2.1c virus is low in the absence of the Q222L, G224S, H103Y, N220K and T315I. A typical
20 amino acid deletion with loss of four corresponding glycosylation sites in the NA stalk region was
visible. Though three NA resistance markers were detected, the virus was predicted to be sensitive
to NA inhibitor. This is the first HPAI H5N1 outbreak in Sabah. The introduction of this virus into East
Malaysia for the first time raised an alert alarm of the future epidemic potential. Strict farm biosecurity,
continuous surveillance programme in poultry, wild birds, migratory birds; molecular epidemiology as
well as risk assessment for the virus with pandemic potential are needed in dealing with emergence
of new influenza virus in the country.
3.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.