1.Experimental infection of tick cells with Nipah virus
Phoon, W.H. ; Bell-Sakyi, L. ; AbuBakar, S. ; Chang, L.Y.
Tropical Biomedicine 2023;40(No.1):29-36
Nipah virus (NiV), a highly pathogenic henipavirus of the family Paramyxoviridae, which causes fatal
encephalitis in 40-70% of affected patients, was first reported in Malaysia over 20 years ago. Pteropid
bats are the natural hosts of henipaviruses, and ticks have been proposed as a possible link between
bats and mammalian hosts. To investigate this hypothesis, infection of the tick cell line IDE8 with NiV
was examined. Presence of viral RNA and antigen in the NiV-infected tick cells was confirmed. Infectious
virions were recovered from NiV-infected tick cells and ultrastructural features of NiV were observed
by electron microscopy. These results suggest that ticks could support NiV infection, potentially playing
a role in transmission.
2.Toxoplasma gondii infection among selected indigenous community in Sarawak, East Malaysia
Ngui, R. ; Hassan, N.A. ; Chang, L.Y. ; Teh, S.J.C. ; Chua, K.H. ; Kee, B.P. ; Hoe, S.Z. ; Lim, Y.A.L.
Tropical Biomedicine 2020;37(No.1):155-164
Toxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis in humans. To date, little is known about T. gondii infection among the indigenous community, particularly in East Malaysia. This study was conducted to determine the status of T. gondii infection and to investigate associated risk factors among the indigenous community of Sarawak, East Malaysia. The sociodemographic data was obtained using a pretested questionnaire. A serological test was done to detect the presence of specific IgM and IgG antibodies against T. gondii in serum samples. A nested polymerase chain reaction (PCR) was used to determine acute infection among seropositive individuals. The overall seroprevalence of T. gondii infection was 50% (95% CI = 43.3 – 56.7). From this subset, 40.1%, 5.7%, and 4.2% were positive for anti-T. Gondii IgG antibodies, IgM, and both IgG and IgM, respectively. Four seropositive samples were amplified through PCR. None of the pregnant women tested positive for T. gondii infection based on the serological and PCR assays. A significant association was found between age, low monthly household income, unemployment, usage of untreated water and close contact with T. gondii seropositive cats. These results provide basic information on T. gondii infection and may be useful for policymakers to initiate prevention and control programs, especially amongst pregnant women and women of childbearing age in the indigenous community.
3.A conventional multiplex PCR for the detection of four common soil-transmitted nematodes in human feces: development and validation
Hassan, N.A. ; Noor Badi, F.A. ; Mohd-Shaharuddin, N. ; Wan Yusoff, W.S. ; Lim, Y.A.L. ; Chua, K.H. ; Sidi Omar, S.F.N. ; Chang, L.Y. ; Majid, H.A. ; Ngui, R.
Tropical Biomedicine 2022;39(No.1):135-142
Soil-transmitted helminth (STH) infections, mainly caused by Ascaris lumbricoides, Trichuris
trichiura, and hookworms, are among the most common intestinal parasites that infect
humans. The infections are widely distributed throughout tropical and subtropical countries,
including Malaysia, particularly in underprivileged communities. Microscopic and culture
techniques have been used as a gold standard for diagnostic techniques. However, these
methods yield low sensitivity and specificity, laborious and time-consuming. Therefore,
simple, rapid, and accurate alternative methods are needed for the simultaneous detection
of STH infections. Although advanced technologies such as real-time multiplex PCR have
been established, the use of this technique as a routine diagnostic is limited due to the
high cost of the instrument. Therefore, a single-round multiplex conventional PCR assay for
rapid detection of four STH species in the fecal sample was developed in this study. To
perform the single-round multiplex PCR, each pair of species-specific primers was selected
from target genes, including Ancylostoma duodenale (Internal Transcribed Spacer 2; accession
No. AJ001594; 156 base pair), Necator americanus (ITS 2; accession No. AJ001599; 225 base pair),
Ascaris lumbricoides (Internal Transcribed Spacer 1; accession No. AJ000895; 334 base pair)
and Trichuris triciura (partial ITS 1, 5.8s rRNA and partial ITS 2; accession No. AM992981; 518
base pair). The results showed that the newly designed primers could detect the DNA of STH
at low concentrations (0.001 ng/μl) with no cross-amplification with other species. This
assay enables the differentiation of single infections as well as mixed infections. It could
be used as an alternative and is a convenient method for the detection of STHs, especially
for the differentiation of N. americanus and A. duodenale.