Displaying publications 1 - 20 of 27 in total

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  1. Voon K, Premnath N
    Med J Malaysia, 2020 11;75(6):762-763.
    PMID: 33219197
    COVID-19 has infected more than 10 million people worldwide and it has become one of the biggest challenges in the modern medical history. Wearing of face masks, social distancing, effective hand hygiene and the use of appropriate personal protective equipment are important in flattening the curve of the pandemic. The role of the surgeons in this battle against COVID-19 include curbing the spread of the disease, to protect and preserve the surgical workforce and to ensure the continuance of essential surgical services. We report our experience in dealing with the COVID-19 outbreak in a tertiary surgical centre in the Penang General Hospital in Northern Malaysia.
  2. Chem YK, Chua KB, Malik Y, Voon K
    Trop Biomed, 2015 Jun;32(2):344-51.
    PMID: 26691263 MyJurnal
    Monoclonal antibody-escape variant of dengue virus type 1 (MabEV DEN-1) was discovered and isolated in an outbreak of dengue in Klang Valley, Malaysia from December 2004 to March 2005. This study was done to investigate whether DEN152 (an isolate of MabEV DEN-1) is a product of recombination event or not. In addition, the non-synonymous mutations that correlate with the monoclonal antibody-escape variant were determined in this study. The genomes of DEN152 and two new DEN-1 isolates, DENB04 and DENK154 were completely sequenced, aligned, and compared. Phylogenetic tree was plotted and the recombination event on DEN152 was investigated. DEN152 is sub-grouped under genotype I and is closely related genetically to a DEN-1 isolated in Japan in 2004. DEN152 is not a recombinant product of any parental strains. Four amino acid substitutions were unique only to DEN 152. These amino acid substitutions were (Ser)[326](Leu), (Ser)[340](Leu) at the deduced E protein, (Ile)[250](Thr) at NS1 protein, and (Thr)[41](Ser) at NS5 protein. Thus, DEN152 is an isolate of the emerging monoclonal antibody-escape variant DEN-1 that escaped diagnostic laboratory detection.
  3. Theint HT, Walsh JE, Wong ST, Voon K, Shitan M
    Spectrochim Acta A Mol Biomol Spectrosc, 2019 Jul 05;218:348-358.
    PMID: 31026712 DOI: 10.1016/j.saa.2019.04.008
    A laboratory prototype system that correlates murine blood absorbance with degree of infection for Plasmodium berghei and Trypanosoma avensi has been designed, constructed and tested. A population (n = 6) of control uninfected, Plasmodium infected and Trypanosoma infected BALB/c mice were developed and spectral absorption measurements pre and post infection were made every 3 days. A fibre optic spectrometer set-up was used as the basis of a laboratory prototype biosensor that uses the Beer Lambert Law to relate Ultraviolet-Visible-Near-infrared absorbance data to changes in murine blood chemistry post infection. Spectral absorption results indicate a statistically relevant correlation at a 650 nm with infection for Plasmodium from between 4 and 7 sampling days' post infection, in spite of significant standard deviations among the sample populations for control and infected mice. No significant spectral absorption change for Trypanosoma infection was been detected from the current data. Corresponding stained slides of control and infected blood at each sampling date were taken with related infected cell counts determined and these correlate well for Plasmodium absorbance at 650 nm.
  4. Tan YF, Teng CL, Chua KB, Voon K
    J Infect Dev Ctries, 2017 Mar 31;11(3):215-219.
    PMID: 28368854 DOI: 10.3855/jidc.9112
    INTRODUCTION: Pteropine orthoreovirus (PRV) is an emerging zoonotic respiratory virus that has spilled over from bats to humans. Though initially found only in bats, further case studies have found viable virus in ill patients.

    METHODOLOGY: PubMed was queried with the keywords of Nelson Bay orthoreovirus OR Pteropine orthoreovirus OR Melaka orthoreovirus OR Kampar orthoreovirus, and returned 17 hits.

    RESULTS: Based on prevalence studies, the presence of PRV has been reported in Malaysia and Vietnam, both developing countries. Other case reports also provide further evidence of the presence of PRV in the Southeast Asian region. Despite the absence of PRV in their home countries, travellers from Hong Kong and Japan to Indonesia have returned to their countries ill with this virus, indicating that local communities in Indonesia might be affected by this virus.

    CONCLUSIONS: This work aims to bring to light this emerging zoonotic respiratory virus circulating among developing countries in Southeast Asia. To improve the understanding of PRV of the medical and scientific community in the Southeast Asian region, this work introduces the general features of PRV, reports of imported PRV, prevalence, and clinical features of PRV. Gaps in knowledge about PRV have also been identified in this work, and we hope that future studies can be undertaken to improve our understanding of this virus.

  5. Siew ZY, Loh A, Segeran S, Leong PP, Voon K
    DNA Cell Biol, 2023 Jun;42(6):289-304.
    PMID: 37015068 DOI: 10.1089/dna.2022.0561
    Orthoreovirus is a nonenveloped double-stranded RNA virus under the Reoviridae family. This group of viruses, especially mammalian orthoreovirus (MRV), are reported with great therapeutic values due to their oncolytic effects. In this review, the life cycle and oncolytic effect of MRV and a few emerging reoviruses were summarized. This article also highlights the challenges and strategies of utilizing MRV and the emerging reoviruses, avian orthoreovirus (ARV) and pteropine orthoreovirus (PRV), as oncolytic viruses (OVs). Besides, the emergence of potential ARV and PRV as OVs were discussed in comparison to MRV. Finally, the risk of reovirus as zoonosis or reverse zoonosis (zooanthroponosis) were debated, and concerns were raised in this article, which warrant continue surveillance of reovirus (MRV, ARV, and PRV) in animals, humans, and the environment.
  6. Voon K, Ng QM, Yu M, Wang LF, Chua KB
    PMID: 23077814
    Viruses in the family Picornaviridae are classified into nine genera. Within the family Picornaviridae, two species: Encephalomyocarditis virus and Theilovirus, are listed under the genus Cardiovirus. A novel Theilovirus, Saffold virus (SAFV), was first reported in 2007. Since then, numerous SAFV isolates have been detected around the world and genetic recombinations have been reported among them. In 2009, SAFV-Penang was isolated from a febrile child with influenza-like illness in Malaysia. SAFV-Penang is a genotype 3 SAFV. In this study we investigated the genome features of SAFV-Penang to exclude the possibility it is a recombinant variant. SAFV-Penang was found not to be a recombinant variant but to have three unique non-synonymous substitutions, alanine [A689], lysine [K708] and isoleucine [I724] in the VP1 protein.
  7. Chua KB, Voon K, Yu M, Keniscope C, Abdul Rasid K, Wang LF
    PLoS One, 2011;6(10):e25434.
    PMID: 22022394 DOI: 10.1371/journal.pone.0025434
    Bats are increasingly being recognized as important reservoir hosts for a large number of viruses, some of them can be highly virulent when they infect human and livestock animals. Among the new bat zoonotic viruses discovered in recent years, several reoviruses (respiratory enteric orphan viruses) were found to be able to cause acute respiratory infections in humans, which included Melaka and Kampar viruses discovered in Malaysia, all of them belong to the genus Orthoreovirus, family Reoviridae. In this report, we describe the isolation of a highly related virus from an adult patient who suffered acute respiratory illness in Malaysia. Although there was no direct evidence of bat origin, epidemiological study indicated the potential exposure of the patient to bats before the onset of disease. The current study further demonstrates that spillover events of different strains of related orthoreoviruses from bats to humans are occurring on a regular basis, which calls for more intensive and systematic surveillances to fully assess the true public health impact of these newly discovered bat-borne zoonotic reoviruses.
  8. Voon K, Chua KB, Yu M, Crameri G, Barr JA, Malik Y, et al.
    J Gen Virol, 2011 Dec;92(Pt 12):2930-2936.
    PMID: 21849518 DOI: 10.1099/vir.0.033498-0
    We previously described three new Malaysian orthoreoviruses designated Pulau virus, Melaka virus and Kampar virus. Melaka and Kampar viruses were shown to cause respiratory disease in humans. These viruses, together with Nelson Bay virus, isolated from Australian bats, are tentatively classified as different strains within the species Pteropine orthoreovirus (PRV), formerly known as Nelson Bay orthoreovirus, based on the small (S) genome segments. Here we report the sequences of the large (L) and medium (M) segments, thus completing the whole-genome characterization of the four PRVs. All L and M segments were highly conserved in size and sequence. Conserved functional motifs previously identified in other orthoreovirus gene products were also found in the deduced proteins encoded by the cognate segments of these viruses. Detailed sequence analysis identified two genetic lineages divided into the Australian and Malaysian PRVs, and potential genetic reassortment among the M and S segments of the three Malaysian viruses.
  9. Chiew MY, Boo NY, Voon K, Cheong SK, Leong PP
    Leuk Lymphoma, 2017 01;58(1):162-170.
    PMID: 27185517
    Acute monocytic leukemia (AML-M5), a subtype of acute myeloid leukemia (AML), affects mostly young children and has poor prognosis. The mechanisms of treatment failure of AML-M5 are still unclear. In this study, we generated iPSC from THP-1 cells from a patient with AML-M5, using retroviruses encoding the pluripotency-associated genes (OCT3/4, SOX2, KLF4 and c-MYC). These AML-M5-derived iPSC showed features similar with those of human embryonic stem cells in terms of the morphology, gene expression, protein/antigen expression and differentiation capability. Parental-specific markers were down-regulated in these AML-M5-derived iPSCs. Expression of MLL-AF9 fusion gene (previously identified to be associated with pathogenesis of AML-M5) was observed in all iPSC clones as well as parental cells. We conclude that AML-M5-specific iPSC clones have been successfully developed. This disease model may provide a novel approach for future study of pathogenesis and therapeutic intervention of AML-M5.
  10. Krishnappa P, Kong HM, Mohamad IB, Voon K, Somanath SD
    J Obstet Gynaecol Res, 2017 May;43(5):923-928.
    PMID: 28181356 DOI: 10.1111/jog.13277
    AIM: The aim of this study was to determine the allelic frequency of single nucleotide polymorphisms (SNPs) in the human CD40 gene in cervical cancer.

    METHODS: A total of 200 cases were selected from the records of the Department of Pathology, Hospital Tuanku Jaafar, Seremban, Malaysia. The samples were collected in three separate groups: cervicitis (n = 61), cervical intraepithelial neoplasia (n = 69), and cervical carcinoma (n = 70). The patients' demographic data and the respective paraffin-embedded tissue samples from Hospital Tuanku Jaafar, Seremban were obtained upon consent. The sample tissues were submitted for DNA extraction using G-spin Total DNA Extraction Kit. DNA obtained was then submitted for nested PCR before restriction enzyme digestion.

    RESULTS: SNP rs1883832 showed higher prevalence of T alleles in the cervical carcinoma group compared to the control groups and in rs3765459, a higher prevalence of G alleles in the cervical carcinoma group was noted. The results of rs1800686 and rs4810485 were insignificant.

    CONCLUSION: The data from our study indicates a potential association between the rs1883832 and rs3765459 CD40 gene polymorphism and susceptibility to cervical cancer.

  11. Tan YF, Lim CY, Chong CW, Lim PKC, Yap IKS, Leong PP, et al.
    Intervirology, 2018;61(2):92-95.
    PMID: 30121676 DOI: 10.1159/000491602
    BACKGROUND: The giant amoebal viruses of Mimivirus and Marseillevirus are large DNA viruses and have been documented in water, soil, and sewage samples. The trend of discovering these giant amoebal viruses has been increasing throughout Asia with Japan, India, and Saudi Arabia being the latest countries to document the presence of these viruses. To date, there have been no reports of large amoebal viruses being isolated in South East Asia.

    OBJECTIVE: In this study, we aim to discover these viruses from soil samples in an aboriginal village (Serendah village) in Peninsular -Malaysia.

    METHOD AND RESULTS: We successfully detected and isolated both Mimivirus-like and Marseillevirus-like viruses using Acanthamoeba castellanii. Phylogeny analysis identified them as Mimivirus and Marseillevirus, respectively.

    CONCLUSION: The ubiquitous nature of both Mimivirus and Marseillevirus is further confirmed in our study as they are detected in higher quantity in soil that is near to water vicinities in an aboriginal village in Peninsular Malaysia. However, this study is limited by our inability to investigate the impact of Mimivirus and Marseillevirus on the aboriginal villagers. More studies on the potential impact of these viruses on human health, especially on the aborigines, are warranted.

  12. Chua KB, Voon K, Yu M, Ali WN, Kasri AR, Wang LF
    Emerg Infect Dis, 2011 Aug;17(8):1562-4.
    PMID: 21801653 DOI: 10.3201/eid1708.101380
  13. Voon K, Huang CK, Patel A, Wong LF, Lu YC, Hsin MC
    J Metab Bariatr Surg, 2021 Jun;10(1):32-41.
    PMID: 36687754 DOI: 10.17476/jmbs.2021.10.1.32
    PURPOSE: Both primary and revisional bariatric surgery are on the rise due to global obesity pandemic. This study aimed to assess the indications for revision after one-anastomosis gastric bypass (OAGB) and the outcomes after laparoscopic conversion of OAGB to roux-en-y gastric bypass (RYGB).

    MATERIALS AND METHODS: Retrospective review on patients that had undergone conversion of OAGB to RYGB between June 2007-June 2019 in a tertiary bariatric center, followed by literature review.

    RESULTS: Out of 386 revisional bariatric surgery, a total of 14 patients underwent laparoscopic conversion of OAGB to RYGB. The mean age was 44.7 with 71% female. The mean pre-revision BMI was 29.2 kg/m2. The primary indications for revision were bile reflux (n=7), marginal ulcer (n=3), inadequate weight loss or weight regain (IWL/WR) (n=3) and protein-calorie malnutrition (n=1). Conversion of OAGB to RYGB was completed laparoscopically in all cases. The mean length of stay was 4.1 days. There was no intraoperative or early post-operative complication. The mean total weight loss (rTWL%) after revision at year one, year three and year five post-revision were 11.5%, 18.1% and 29.1%, respectively. All patients achieved resolution of bile reflux and marginal ulcer. There was no mortality in this cohort.

    CONCLUSION: Bile reflux, marginal ulcer, IWL/WR and malnutrition were the main indications for revision after OAGB in this study. In concordance with the available evidence, laparoscopic conversion of OAGB to RYGB was safe and effective in dealing with late complications of OAGB.

  14. Johari NA, Voon K, Toh SY, Sulaiman LH, Yap IKS, Lim PKC
    PLoS Negl Trop Dis, 2019 Nov;13(11):e0007889.
    PMID: 31730672 DOI: 10.1371/journal.pntd.0007889
    Dengue fever is endemic in Malaysia, contributing to significant economic and health burden in the country. Aedes aegypti and Ae. albopictus are the main vectors of the dengue virus (DENV), which circulates in sylvatic and human transmission cycles and has been present in Malaysia for decades. The study investigated the presence and distribution of DENV in urban localities in the Klang Valley, Peninsular Malaysia. A total of 364 Ae. aegypti and 1,025 Ae. albopictus larvae, and 10 Ae. aegypti and 42 Ae. albopictus adult mosquitoes were screened for the presence of DENV. In total, 31 (2.2%) samples were positive, of which 2 Ae. albopictus larvae were co-infected with two serotypes, one with DENV-2 and DENV-3 and the other with DENV-3 and DENV-4. Phylogenetic analysis determined that the isolates belonged to DENV-1 genotype I (1 Ae. aegypti adult), DENV-2 (1 Ae. albopictus larva), DENV-3 genotype V (3 Ae. aegypti larvae and 10 Ae. albopictus larvae) and DENV-4 genotype IV (6 Ae. aegypti larvae and 12 Ae. albopictus larvae), a sylvatic strain of DENV-4 which was most closely related with sylvatic strains isolated from arboreal mosquitoes and sentinel monkeys in Peninsular Malaysia in the 1970s. All four DENV serotypes were co-circulating throughout the study period. The detection of a sylvatic strain of DENV-4 in Ae. aegypti and Ae. albopictus mosquitoes in urban areas in Peninsular Malaysia highlights the susceptibility of these vectors to infection with sylvatic DENV. The infectivity and vector competence of these urban mosquitoes to this strain of the virus needs further investigation, as well as the possibility of the emergence of sylvatic virus into the human transmission cycle.
  15. Siew ZY, Asudas E, Khoo CT, Cho GH, Voon K, Fang CM
    Arch Microbiol, 2024 Feb 28;206(3):130.
    PMID: 38416180 DOI: 10.1007/s00203-024-03846-3
    The human immunodeficiency virus (HIV) is a type of lentivirus that targets the human immune system and leads to acquired immunodeficiency syndrome (AIDS) at a later stage. Up to 2021, there are millions still living with HIV and many have lost their lives. To date, many anti-HIV compounds have been discovered in living organisms, especially plants and marine sponges. However, no treatment can offer a complete cure, but only suppressing it with a life-long medication, known as combined antiretroviral therapy (cART) or highly active antiretroviral therapy (HAART) which are often associated with various adverse effects. Also, it takes many years for a discovered compound to be approved for clinical use. Thus, by employing advanced technologies such as automation, conducting systematic screening and testing protocols may boost the discovery and development of potent and curative therapeutics for HIV infection/AIDS. In this review, we aim to summarize the antiretroviral therapies/compounds and their associated drawbacks since the discovery of azidothymidine. Additionally, we aim to provide an updated analysis of the most recent discoveries of promising antiretroviral candidates, along with an exploration of the current limitations within antiretroviral research. Finally, we intend to glean insightful perspectives and propose future research directions in this crucial area of study.
  16. Chua KB, Voon K, Crameri G, Tan HS, Rosli J, McEachern JA, et al.
    PLoS One, 2008;3(11):e3803.
    PMID: 19030226 DOI: 10.1371/journal.pone.0003803
    First discovered in the early 1950s, reoviruses (respiratory enteric orphan viruses) were not associated with any known disease, and hence named orphan viruses. Recently, our group reported the isolation of the Melaka virus from a patient with acute respiratory disease and provided data suggesting that this new orthoreovirus is capable of human-to-human transmission and is probably of bat origin. Here we report yet another Melaka-like reovirus (named Kampar virus) isolated from the throat swab of a 54 year old male patient in Kampar, Perak, Malaysia who was suffering from high fever, acute respiratory disease and vomiting at the time of virus isolation. Serological studies indicated that Kampar virus was transmitted from the index case to at least one other individual and caused respiratory disease in the contact case. Sequence analysis of the four small class genome segments indicated that Kampar and Melaka viruses are closely related. This was confirmed by virus neutralization assay, showing an effective two-way cross neutralization, i.e., the serum against one virus was able to neutralize the other. Although the exact origin of Kampar virus is unknown, epidemiological tracing revealed that the house of the index case is surrounded by fruit trees frequently visited by fruit bats. There is a high probability that Kampar virus originated from bats and was transmitted to humans via bat droppings or contaminated fruits. The discovery of Kampar virus highlights the increasing trend of emergence of bat zoonotic viruses and the need to expand our understanding of bats as a source of many unknown viruses.
  17. Voon K, Tan YF, Leong PP, Teng CL, Gunnasekaran R, Ujang K, et al.
    J Med Virol, 2015 Dec;87(12):2149-53.
    PMID: 26106066 DOI: 10.1002/jmv.24304
    This study aims to assess the incidence rate of Pteropine orthreovirus (PRV) infection in patients with acute upper respiratory tract infection (URTI) in a suburban setting in Malaysia, where bats are known to be present in the neighborhood. Using molecular detection of PRVs directly from oropharyngeal swabs, our study demonstrates that PRV is among one of the common causative agents of acute URTI with cough and sore throat as the commonest presenting clinical features. Phylogenetic analysis on partial major outer and inner capsid proteins shows that these PRV strains are closely related to Melaka and Kampar viruses previously isolated in Malaysia. Further study is required to determine the public health significance of PRV infection in Southeast Asia, especially in cases where co-infection with other pathogens may potentially lead to different clinical outcomes.
  18. Muniandy G, Kamaruzaman L, Jan TH, Mohd R, Neesam MT, Fong Voon K, et al.
    Acta Med Indones, 2023 Jan;55(1):78-82.
    PMID: 36999269
    Cefepime is a frequently used fourth-generation cephalosporin antibiotic for a wide variety of infections. Toxic levels of this drug can cause neurological complications. The most common neurological adverse event of cefepime is headache and lightheadedness. Here, we presented a case of cefepime induced encephalopathy in a 57-year-old female patient with acute on chronic kidney disease. With an accurate diagnosis that requires a high index of clinical suspicion, prompt management was instituted. She had full resolution of symptoms following discontinuation of the medication and also emergent dialysis.
  19. Siew ZY, Lai ZJ, Ho QY, Ter HC, Ho SH, Wong ST, et al.
    Trop Biomed, 2023 Dec 01;40(4):462-470.
    PMID: 38308834 DOI: 10.47665/tb.40.4.012
    Bats are flying mammals with unique immune systems that allow them to hold many pathogens. Hence, they are recognised as the reservoir of many zoonotic pathogens. In this study, we performed molecular detection to detect coronaviruses, paramyxoviruses, pteropine orthoreoviruses and dengue viruses from samples collected from insectivorous bats in Krau Reserve Forest. One faecal sample from Rhinolophus spp. was detected positive for coronavirus. Based on BLASTN, phylogenetic analysis and pairwise alignment-based sequence identity calculation, the detected bat coronavirus is most likely to be a bat betacoronavirus lineage slightly different from coronavirus from China, Philippines, Thailand and Luxembourg. In summary, continuous surveillance of bat virome should be encouraged, as Krau Reserve Forest reported a wide spectrum of biodiversity of insectivorous and fruit bats. Moreover, the usage of primers for the broad detection of viruses should be reconsidered because geographical variations might possibly affect the sensitivity of primers in a molecular approach.
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