Genetic polymorphism and natural selection in the C-terminal 42 kDa region of merozoite surface protein-1 (MSP-1) among Plasmodium knowlesi samples from Malaysia

Background: The merozoite surface protein-1 (MSP-1) gene encodes for a leading malaria vaccine candidate antigen. However, its extensive polymorphic nature represents a major obstacle to the development of a protective vaccine. Previously, a pilot study was carried out to explore the sequence variation of the C-terminal 42 kDa fragment within P. knowlesi MSP-1 gene (PkMSP-142) based on 12 clinical samples; however, further study on an adequate sample size is vital in estimating the genetic diversity of the parasite population. Methods: In the present study, we included a larger sample size of P. knowlesi (83 samples) covering eight states of Malaysia to determine the genetic polymorphism, natural selection and haplotype groups of the gene fragment coding PkMSP-142. The region flanking PkMSP-142 was amplified by PCR and directly sequenced. Genetic diversity, haplotype diversity, population genetic differentiation and natural selection were determined in order to study the polymorphic characteristic of PkMSP-142. Results: A high level of genetic diversity (Hd = 0.970 ± 0.007; л = 0.01079 ± 0.00033) was observed among the 83 P. knowlesi samples, confirming the extensive genetic polymorphism exhibited among the P. knowlesi population found in Malaysia. A total of 18 distinct haplotypes with 17 amino acid changes were identified, whereby 15 were new haplotypes. High population differentiation values were observed within samples from Peninsular Malaysia and Malaysian Borneo. The 42 kDa fragments of P. knowlesi from Malaysian Borneo were found to be acting on balancing selection whilst purifying selection was suggested to act on isolates from Peninsular Malaysia. The separation of PkMSP-142 haplotypes into two main groups based on geographical separation has further supported the existence of two distinct P. knowlesi lineages. Conclusions: A high level of genetic diversity was observed among PkMSP-142 in Malaysia, whereby most of the polymorphisms were found within the 33 kDa region. Taken together, these data will be useful in order to understand the nature of P. knowlesi population in Malaysia as well as the design and development of a MSP-142 based knowlesi malaria vaccin

Molecular epidmiology of giardia duodenalis infections among indigenous communities in rural Malaysia / Choy Seow Huey

Giardia duodenalis is a protozoan parasite that can cause significant diarrhoeal diseases and is the most common intestinal protozoan parasite worldwide. It affects especially children from the rural areas, who are also the most vulnerable group that suffers from nutritional disorders that have been linked to this parasite. Being part of the complex group of parasitic, bacterial and viral diseases that debilitate the susceptible communities in developing regions from achieving full development potential, Giardia was included in the ‘Neglected Diseases Initiative’ in 2004. In Malaysia, information on the epidemiology of Giardia infection among different indigenous communities is limited. Orang Asli, the indigenous people that live in West Malaysia are the communities most at risk of acquiring parasitic infections. Meanwhile, the prevalence of the infection among indigenous people in East Malaysia has not been well explored. In addition, there is a scarcity of information on the genetic diversity and the dynamics of transmission of G. duodenalis. This cross-sectional study was carried out to investigate the prevalence and risk factors of Giardia infection among indigenous people in rural Malaysia. It also aims to identify G. duodenalis assemblages and sub-assemblages present in these communities based on multilocus genotyping approach. Moreover, the genetic data obtained by the present study were combined with a larger global sequence data for genetic diversity analyses. Faecal samples were collected between April 2011 and February 2013 from 1,330 participants from seven states of Malaysia. The samples were examined by wet mount and formalin-ether sedimentation methods while demographic, socioeconomic and environmental information was collected using a pre-tested questionnaire. Samples positive for Giardia were genotyped by using markers targeting the glutamate dehydrogenase (gdh), beta-giardin (bg) and triose phosphate isomerase (tpi) genes. The tpi sequences obtained by the present study as well as sequences from the global data obtained from the NCBI GenBank were used to analyse the population structure of G. duodenalis. The overall prevalence of Giardia infection was 11.6%. The prevalence was found to be significantly higher among the aboriginal population in West Malaysia (13.6%) when compared to the indigenous people in East Malaysia (5.8%). Multivariate logistic regression identified age of ≤ 12 years, lacking of toilet at household, not washing hands before eating, not washing hands after playing with animals, not boiling water before consumption, bathing in the river, and not wearing shoes when outside as the significant risk factors of Giardia infection among these communities. A significant association between Giardia infection and diarrhoea iv among the studied population was reported. The frequency of diarrhoeal cases was significantly higher among Giardia-infected participants from West Malaysia when compared to their counterparts from East Malaysia. Of the 154 positive samples, 138 successfully yielded amplification by at least one of the markers (gdh, bg and tpi). Genotyping result showed that 69 of the isolates were classified as assemblage A and 69 were classified as assemblage B. Mixed infections were detected in 49 samples using a tpi-based assemblage specific protocol. At the sub-assemblages level, isolates belonged to assemblage A were AII. High nucleotide variation found in isolates of assemblage B made subtyping difficult to achieve. Infection with Giardia assemblage A was significantly associated with the age of ≤ 12 years, not boiling water before drinking and had close contact with domestic animals. With regard to assemblage B, large family size, bathing in river, practicing indiscriminate/open defecation, not washing hands before eating, and playing with soil were the associated factors. No association between the assemblages and the presence of symptoms was found. Analysis of the Malaysian and global data showed that assemblages A, B, and E (the most prevalent assemblages in humans and animals), have different level of genetic diversity. Assemblage B had the highest level of both haplotype diversity and nucleotide diversity, followed by assemblage E. The analysis also revealed population expansion and high gene flow in all assemblages. In conclusion, the present study shows that the prevalence of Giardia infection is still high and of public health concern among indigenous populations in rural Malaysia. The findings of assemblage B and the anthroponotic genotype AII implicate human-to-human transmission as the most possible mode of transmission among Malaysian indigenous people. Meanwhile, the population genetic study provides new insight into the genetic diversity of Giardia assemblages in different geographical regions and should have brought enlightenment to the dynamics and distribution of Giardia infection. In view of the significant difference in the prevalence of Giardia infection among the different indigenous communities, implemented policies that may help in controlling the infection should be identified. Providing proper sanitation, as well as provision of clean drinking water and proper health education regarding good personal hygiene practices will help significantly in reducing the prevalence and burden of Giardia infection in these communities

The burden of moderate-to-heavy soil-transmitted helminth infections among rural malaysian aborigines: an urgent need for an integrated control programme.

International audienceBACKGROUND: Soil-transmitted helminth (STH) infections, among the most common neglected tropical diseases, continue to be a major threat to the health and socioeconomic wellbeing of infected people especially children in developing countries. METHODS: A cross-sectional study among 254 aboriginal schoolchildren was conducted in order to determine the current prevalence and intensity of infections and to investigate the potential risk factors associated with moderate-to-heavy burden of STH infections among these children. RESULTS: Overall, 93.7% of children were found to be infected with one or more STH species. The prevalence of trichuriasis, ascariasis and hookworm infections were 84.6%, 47.6% and 3.9%, respectively. Almost half of the participants had heavy trichuriasis, one-quarter had heavy ascariasis whereas all hookworm infections were light infections. Overall, moderate-to-heavy STH infections accounted for 56.7% of the total infections. Univariate analysis revealed that those using untreated water supply (P = 0.013), living in houses without toilets (P = 0.027) and having domestic animals in the houses (P = 0.044) had significantly higher prevalence of moderate-to-heavy infections than others. Logistic regression analysis confirmed using untreated water for drinking (P = 0.001) and the absence of a toilet in the house (P = 0.003) as significant risk factors of moderate-to-heavy STH infections among these children. CONCLUSION: The high proportion of moderate-to-heavy STH infections further confirms the need for serious attention towards these devastating diseases that has put lives and the future of aboriginal children in jeopardy. Introduction of more poverty alleviation schemes, proper sanitation, provision of clean and safe drinking water, health education, as well as the introduction of periodic school-based deworming programmes are imperative among these communities in order to curtail the transmission and morbidity caused by STH

Genetic polymorphism and natural selection in the C-terminal 42 kDa region of merozoite surface protein-1 (MSP-1) among Plasmodium knowlesi samples from Malaysia

Background: The merozoite surface protein-1 (MSP-1) gene encodes for a leading malaria vaccine candidate antigen. However, its extensive polymorphic nature represents a major obstacle to the development of a protective vaccine. Previously, a pilot study was carried out to explore the sequence variation of the C-terminal 42 kDa fragment within P. knowlesi MSP-1 gene (PkMSP-142) based on 12 clinical samples; however, further study on an adequate sample size is vital in estimating the genetic diversity of the parasite population. Methods: In the present study, we included a larger sample size of P. knowlesi (83 samples) covering eight states of Malaysia to determine the genetic polymorphism, natural selection and haplotype groups of the gene fragment coding PkMSP-142. The region flanking PkMSP-142 was amplified by PCR and directly sequenced. Genetic diversity, haplotype diversity, population genetic differentiation and natural selection were determined in order to study the polymorphic characteristic of PkMSP-142. Results: A high level of genetic diversity (Hd = 0.970 ± 0.007; cyrillic letter El = 0.01079 ± 0.00033) was observed among the 83 P. knowlesi samples, confirming the extensive genetic polymorphism exhibited among the P. knowlesi population found in Malaysia. A total of 18 distinct haplotypes with 17 amino acid changes were identified, whereby 15 were new haplotypes. High population differentiation values were observed within samples from Peninsular Malaysia and Malaysian Borneo. The 42 kDa fragments of P. knowlesi from Malaysian Borneo were found to be acting on balancing selection whilst purifying selection was suggested to act on isolates from Peninsular Malaysia. The separation of PkMSP-142 haplotypes into two main groups based on geographical separation has further supported the existence of two distinct P. knowlesi lineages. Conclusions: A high level of genetic diversity was observed among PkMSP-142 in Malaysia, whereby most of the polymorphisms were found within the 33 kDa region. Taken together, these data will be useful in order to understand the nature of P. knowlesi population in Malaysia as well as the design and development of a MSP-142 based knowlesi malaria vaccine

The study of seroprevalence of hepatitis E virus and an investigation into the lifestyle behaviours of the aborigines in Malaysia

Malaysia is a non-endemic country for hepatitis E virus (HEV) infection. However, seroprevalence as high as 50% among samples of aboriginal people were reported over two decades ago. A total of 207 samples collected from seven aboriginal villages in rural settlements across two states in Malaysia were analysed for anti-HEV IgG and IgM by an enzyme-linked immunoassay. Following the detection of anti-HEV seroprevalence, we organized health outreach to inform and educate the community. Qualitative interviews were conducted with individuals tested positive for anti-HEV antibodies. Data derived from interviews and observations were used to investigate possible lifestyle behaviours associated with HEV infection. Anti-HEV IgG was detected in six samples (5.9%) from the village of Dusun Kubur. Qualitative inquiry and observation study revealed poor dietary and household hygiene, contaminated food and water, contact with animal faeces, unsanitary and domestic waste disposal, and wildlife reservoirs could be the contributing factors for transmission and acquisition of HEV infection. Investigation during health outreach is important to provide insights for future empirical research and implementation for improvement of lifestyle behaviours among the aborigines. Managing the risk of HEV infection in the aborigines may reduce the risk of HEV transmission to the local communities. © 2020 Blackwell Verlag Gmb

Risk factors associated with EV-A71 seropositivity in Orang Asli populations (n = 248).

<p>Risk factors associated with EV-A71 seropositivity in Orang Asli populations (n = 248).</p

Helminth colonization is associated with increased diversity of the gut microbiota.

Soil-transmitted helminths colonize more than 1.5 billion people worldwide, yet little is known about how they interact with bacterial communities in the gut microbiota. Differences in the gut microbiota between individuals living in developed and developing countries may be partly due to the presence of helminths, since they predominantly infect individuals from developing countries, such as the indigenous communities in Malaysia we examine in this work. We compared the composition and diversity of bacterial communities from the fecal microbiota of 51 people from two villages in Malaysia, of which 36 (70.6%) were infected by helminths. The 16S rRNA V4 region was sequenced at an average of nineteen thousand sequences per samples. Helminth-colonized individuals had greater species richness and number of observed OTUs with enrichment of Paraprevotellaceae, especially with Trichuris infection. We developed a new approach of combining centered log-ratio (clr) transformation for OTU relative abundances with sparse Partial Least Squares Discriminant Analysis (sPLS-DA) to enable more robust predictions of OTU interrelationships. These results suggest that helminths may have an impact on the diversity, bacterial community structure and function of the gut microbiota

Abundance and diversity in the intestinal microbiome in 51 Malaysian subjects.

<p>(<b>Panel A</b>) The number of observed OTUs plotted against age for all 51 individual samples. The number of observed OTUs for most samples was between 1500–4000. (<b>Panel B</b>) Relative abundance of the top phyla represented across the 51 subjects arranged by increasing age. The abundance patterns were largely similar across the individual subjects, except in two of the younger subjects who had high abundance of Actinobacteria (<i>Bifidobacterium</i> sp.) in their stool samples.</p