1.Evaluation of commercial serological assays in Malaysia for detection of anti-Zika virus antibodies
Khoo, H.Y. ; Lee, H.Y. ; Khor, C.S. ; Tan, K.K. ; AbuBakar, S.
Tropical Biomedicine 2021;38(No.4):613-621
The recommended test guidelines for Zika virus (ZIKV) include using both molecular and
serological tools. While the molecular tools are useful for detecting acute infection, the
serological tools are useful for the detection of previous infections. Nevertheless, detection
of ZIKV-specific antibodies remains a challenge due to the high cross-reactivity between
ZIKV and other flaviviruses such as dengue virus (DENV) and Japanese encephalitis virus
(JEV). The objective of this study is to evaluate the commercially available enzyme-linked
immunosorbent assay (ELISA) for the detection of ZIKV IgG. In this study, we evaluated 6
commercially available anti-ZIKV IgG ELISA kits. Pre-characterized serum panels consisting
of 70 sera were selected for the evaluation. The diagnostic accuracy of each ELISA kits was
determined and compared to the gold standard, Foci Reduction Neutralization Test (FRNT).
The present study established that the performance of the NS1-based anti-ZIKV IgG ELISA kit
was superior to that which uses of the E protein as antigen. Overall, commercial ZIKV IgG
ELISA showed varying test performances, with some achieving moderate to high test
sensitivities and specificities. When compared against the FRNT, the test sensitivities ranged
from 7.1% to 78.6%, whereas, the test specificities ranged from 40.0% to 100%. Limitation to
the study includes the cross reactivity between flavivirus and specificity of the kit in
addressing the cross reactivity.
2.Culturable pathogenic bacteria in ticks parasitizing farm animals and rodents in Malaysia
Loong, S.K. ; Lim, F.S. ; Khoo, J.J. ; Lee, H.Y. ; Suntharalingam, C. ; Ishak, S.N. ; Mohd-Taib, F.S. ; AbuBakar, S.
Tropical Biomedicine 2020;37(No.3):803-811
Ticks are vectors of bacteria, protozoa and viruses capable of causing serious and life threatening diseases in humans and animals. Disease transmission occurs through the transfer of pathogen from tick bites to susceptible humans or animals. Most commonly known tick-borne pathogens are obligate intracellular microorganisms but little is known on the prevalence of culturable pathogenic bacteria from ticks capable of growth on artificial nutrient media. One hundred and forty seven ticks originating from dairy cattle, goats and rodents were collected from nine selected sites in Peninsular Malaysia. The culture of surfacesterilized tick homogenates revealed the isolation of various pathogenic bacteria including, Staphylococcus sp., Corynebacterium sp., Rothia sp., Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli and Bacillus sp. and its derived genera. These pathogens are among those that affect humans and animals. Findings from this study suggest that in addition to the regular intracellular pathogens, ticks could also harbor extracellular pathogenic bacteria. Further studies, hence, would be needed to determine if these extracellular pathogens could contribute to human or animal infection.