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Fulltext Independent Emergence of the Cosmopolitan Asian Chikungunya Virus, Philippines 2012

Tan KK, Sy AK, Tandoc AO, Khoo JJ, Sulaiman S, Chang LY, et al.

Sci Rep, 2015 Jul 23;5:12279.
PMID: 26201250 DOI: 10.1038/srep12279

Outbreaks involving the Asian genotype Chikungunya virus (CHIKV) caused over one million infections in the Americas recently. The outbreak was preceded by a major nationwide outbreak in the Philippines. We examined the phylogenetic and phylogeographic relationships of representative CHIKV isolates obtained from the 2012 Philippines outbreak with other CHIKV isolates collected globally. Asian CHIKV isolated from the Philippines, China, Micronesia and Caribbean regions were found closely related, herein denoted as Cosmopolitan Asian CHIKV (CACV). Three adaptive amino acid substitutions in nsP3 (D483N), E1 (P397L) and E3 (Q19R) were identified among CACV. Acquisition of the nsP3-483N mutation in Compostela Valley followed by E1-397L/E3-19R in Laguna preceded the nationwide spread in the Philippines. The China isolates possessed two of the amino acid substitutions, nsP3-D483N and E1-P397L whereas the Micronesian and Caribbean CHIKV inherited all the three amino acid substitutions. The unique amino acid substitutions observed among the isolates suggest multiple independent virus dissemination events. The possible biological importance of the specific genetic signatures associated with the rapid global of the virus is not known and warrant future in-depth study and epidemiological follow-up. Molecular evidence, however, supports the Philippines outbreak as the possible origin of the CACV.
Distribution and dynamics of Wolbachia infection in Malaysian Aedes albopictus

Joanne S, Vythilingam I, Yugavathy N, Leong CS, Wong ML, AbuBakar S

Acta Trop, 2015 Aug;148:38-45.
PMID: 25899523 DOI: 10.1016/j.actatropica.2015.04.003

Wolbachia are maternally transmitted bacteria found in most arthropods and nematodes, but little is known about their distribution and reproductive dynamics in the Malaysian dengue vector Aedes albopictus. In this study, polymerase chain reaction (PCR) was used to determine the presence of Wolbachia from field collected Ae. albopictus from various parts of the country using wsp specific primers. Ae. albopictus had Wolbachia infection ranging from 60 to 100%. No sequence diversity of wsp gene was found within all wAlbA and wAlbB sequences. Our findings suggest that Wolbachia infection amongst the Malaysian Ae. albopictus were not homogenously distributed in all districts in Malaysia. The presence of Wolbachia in different organs of Ae. albopictus was also determined. Wolbachia were only found in the ovaries and midguts of the mosquitoes, while absent in the salivary glands. The effects of Wolbachia on Ae. albopictus fecundity, longevity and egg viability were studied using infected and uninfected colonies. The removal of Wolbachia from Ae. albopictus resulted in reduced fecundity, longevity and egg viability, thus. Wolbachia seem to play a vital role in Ae. albopictus reproductive system.
Fulltext Neglected tropical diseases among the Association of Southeast Asian Nations (ASEAN): overview and update

Hotez PJ, Bottazzi ME, Strych U, Chang LY, Lim YA, Goodenow MM, et al.

PLoS Negl Trop Dis, 2015 Apr;9(4):e0003575.
PMID: 25880767 DOI: 10.1371/journal.pntd.0003575

The ten member states of the Association of Southeast Asian Nations (ASEAN) constitute an economic powerhouse, yet these countries also harbor a mostly hidden burden of poverty and neglected tropical diseases (NTDs). Almost 200 million people live in extreme poverty in ASEAN countries, mostly in the low or lower middle-income countries of Indonesia, the Philippines, Myanmar, Viet Nam, and Cambodia, and many of them are affected by at least one NTD. However, NTDs are prevalent even among upper middle-income ASEAN countries such as Malaysia and Thailand, especially among the indigenous populations. The three major intestinal helminth infections are the most common NTDs; each helminthiasis is associated with approximately 100 million infections in the region. In addition, more than 10 million people suffer from either liver or intestinal fluke infections, as well as schistosomiasis and lymphatic filariasis (LF). Intestinal protozoan infections are widespread, while leishmaniasis has emerged in Thailand, and zoonotic malaria (Plasmodium knowlesi infection) causes severe morbidity in Malaysia. Melioidosis has emerged as an important bacterial NTD, as have selected rickettsial infections, and leptospirosis. Leprosy, yaws, and trachoma are still endemic in focal areas. Almost 70 million cases of dengue fever occur annually in ASEAN countries, such that this arboviral infection is now one of the most common and economically important NTDs in the region. A number of other arboviral and zoonotic viral infections have also emerged, including Japanese encephalitis; tick-borne viral infections; Nipah virus, a zoonosis present in fruit bats; and enterovirus 71 infection. There are urgent needs to expand surveillance activities in ASEAN countries, as well as to ensure mass drug administration is provided to populations at risk for intestinal helminth and fluke infections, LF, trachoma, and yaws. An ASEAN Network for Drugs, Diagnostics, Vaccines, and Traditional Medicines Innovation provides a policy framework for the development of new control and elimination tools. Together with prominent research institutions and universities, the World Health Organization (WHO), and its regional offices, these organizations could implement important public health improvements through NTD control and elimination in the coming decade.
Fulltext The in vitro and in vivo anti-cancer activities of a standardized quassinoids composition from Eurycoma longifolia on LNCaP human prostate cancer cells

Tong KL, Chan KL, AbuBakar S, Low BS, Ma HQ, Wong PF

PLoS One, 2015;10(3):e0121752.
PMID: 25826409 DOI: 10.1371/journal.pone.0121752

Quassinoids are a group of diterpenoids found in plants from the Simaroubaceae family. They are also the major bioactive compounds found in Eurycoma longifolia which is commonly used as traditional medicine in South East Asia to treat various ailments including sexual dysfunction and infertility. These uses are attributed to its ability to improve testosterone level in men. Chronic consumption of E. longifolia extracts has been reported to increase testosterone level in men and animal model but its effect on prostate growth remains unknown. Therefore, the present study investigates the effects of a standardized total quassinoids composition (SQ40) containing 40% of the total quassinoids found in E. longifolia on LNCaP human prostate cancer cell line. SQ40 inhibited LNCaP cell growth at IC50 value of 5.97 μg/mL while the IC50 on RWPE-1 human prostate normal cells was 59.26 μg/mL. SQ40 also inhibited 5α-dihydrotestosterone-stimulated growth in LNCaP cells dose-dependently. The inhibitory effect of SQ40 in anchorage-independent growth of LNCaP cells was also demonstrated using soft agar assay. SQ40 suppressed LNCaP cell growth via G0/G1 phase arrest which was accompanied by the down-regulation of CDK4, CDK2, Cyclin D1 and Cyclin D3 and up-regulation of p21Waf1/Cip1 protein levels. SQ40 at higher concentrations or longer treatment duration can cause G2M growth arrest leading to apoptotic cell death as demonstrated by the detection of poly(ADP-ribose) polymerase cleavage in LNCaP cells. Moreover, SQ40 also inhibited androgen receptor translocation to nucleus which is important for the transactivation of its target gene, prostate-specific antigen (PSA) and resulted in a significant reduction of PSA secretion after the treatment. In addition, intraperitoneal injection of 5 and 10 mg/kg of SQ40 also significantly suppressed the LNCaP tumor growth on mouse xenograft model. Results from the present study suggest that the standardized total quassinoids composition from E. longifolia promotes anti-prostate cancer activities in LNCaP human prostate cancer cells.
The predictive value of uvulo-palatoglossal junctional ulcers as an early clinical sign of exanthem subitum due to human herpesvirus 6

Chua KB, Lam SK, AbuBakar S, Lim ST, Paranjothy M, Koh MT, et al.

J Clin Virol, 2000 Aug;17(2):83-90.
PMID: 10942088

BACKGROUND: The clinical sign of uvulo-palatoglossal junctional (UPJ) ulcers was first noted in 1983 in a 5.5-month-old baby with exanthem subitum (ES). An earlier prospective clinical study showed that there was a strong association of UPJ ulcers and occurrence of ES with a positive predictive value of 95.3% and negative predictive value of 100%.
OBJECTIVE: To determine the value of uvulo-palatoglossal junctional (UPJ) ulcers as an early clinical sign of exanthem subitum (ES) due to human herpesvirus 6 (HHV 6) infection.
STUDY DESIGN: A case-control study of 20 febrile children with UPJ ulcers versus 26 febrile children without UPJ ulcers. These children were followed up for any development of ES and investigated for human herpesvirus 6 (HHV 6) as the causative agents of the febrile episodes.
RESULTS: In this study, 20 out of 46 febrile children aged 3 months to 3 years with UPJ ulcers were virologically and/or serologically confirmed to be due to primary HHV 6 infection. The rest of the 26 children without ulcers did not have HHV 6 infection. Of the 20 children with UPJ ulcers, only 17 of the 19 children with adequate follow-up till subsidence of fever developed ES. None of the 26 children without UPJ ulcers developed ES.
CONCLUSION: Statistically, there was a significant association of UPJ ulcers as an early sign of ES with a positive predictive value of 89.5% and negative predictive value of 100%. This finding also suggests that the presence of UPJ ulcers is a useful pathognomic clinical sign of symptomatic primary HHV 6 infection.
Identification of enterovirus 71 isolates from an outbreak of hand, foot and mouth disease (HFMD) with fatal cases of encephalomyelitis in Malaysia

AbuBakar S, Chee HY, Al-Kobaisi MF, Xiaoshan J, Chua KB, Lam SK

Virus Res, 1999 May;61(1):1-9.
PMID: 10426204

Thirteen enterovirus 71 (EV71) isolates were obtained from both fatal and non-fatal infections of patients seen in Peninsula Malaysia and in Sarawak during an outbreak of hand, foot and mouth disease (HFMD) in Malaysia in 1997, with incidences of fatal brainstem encephalomyelitis. The isolates were identified using immunofluorescence staining, neutralization assays, and partial sequencing of the 5' untranslated regions (UTR). Assessment of the potential genetic relationships of the isolates using the partial 5'UTR sequences suggested clustering of the isolates into at least two main clusters. Isolates from Peninsula Malaysia were found in both clusters whereas Sarawak-derived isolates clustered only in cluster II. Isolates derived from fatal infections, however, occurred in both clusters and no distinctive nucleotide sequences could be attributed to the fatal isolates. Examination of the nucleotide sequences revealed at least 13 nucleotide positions in all the isolates which differ completely from the previously reported EV71 5'UTR sequences. In addition, at least 11 nucleotide position differences within the 5'UTR were noted which differentiated cluster I from cluster II. Predicted secondary RNA structures drawn using the nucleotide sequences also suggested differences between isolates from the two clusters. These findings suggest the presence of at least two potentially virulent EV71 co-circulating in Malaysia during the 1997 HFMD outbreak.
Bacterial communities in Haemaphysalis, Dermacentor and Amblyomma ticks collected from wild boar of an Orang Asli Community in Malaysia

Lim FS, Khoo JJ, Tan KK, Zainal N, Loong SK, Khor CS, et al.

Ticks Tick Borne Dis, 2020 03;11(2):101352.
PMID: 31866439 DOI: 10.1016/j.ttbdis.2019.101352

Ticks are hematophagous vectors of arthropod-borne disease agents globally. In Malaysia, despite seroprevalence studies indicating the presence of tick-borne diseases among the indigenous people, the etiological agents of these diseases are still unclear. These indigenous people, also known as the Orang Asli, still live in forested areas with frequent contact with wildlife. Wild boar are ubiquitously found in the forested areas where the Orang Asli communities are located and are commonly hunted as a food supplement. In this study, we aim to determine the tick species parasitizing wild boar from an Orang Asli community, and explore the tick-associated bacterial communities using 16 s rRNA amplicon sequencing on the Ion Torrent PGM™ platform. A total of 72 ticks were collected from three wild boar and were morphologically identified as Haemaphysalis hystricis (n = 32), Dermacentor compactus (n = 15), Amblyomma testudinarium (n = 13), Dermacentor steini (n = 10) and Dermacentor atrosignatus (n = 2). Across all tick samples, 910 bacterial taxa were identified. Although the bacterial communities were not significantly distinct between tick species in beta-diversity analyses, Coxiella, Rickettsia and Francisella were detected at high relative abundance in H. hystricis, D. compactus and D. steini respectively. Many other bacterial genera, including those that have been described in many different tick species, were also identified, including Pseudomonas, Acinetobacter, Staphylococcus and Corynebacterium. Beta-diversity analyses also showed that the bacterial communities were separated based on the animal host from which the ticks were collected from, suggesting that the bacterial communities here may be influenced by the animal skin microflora, host blood or the environment. PCR screening confirmed the presence of Rickettsia sp. related to spotted fever group Rickettsia in some of the ticks. This study provides baseline knowledge of the microbiome of H. hystricis, D. atrosignatus, D. compactus, D. steini and A. testudinarium parasitizing wild boar in this region. The information gained in this study provides the basis to target our efforts in H. hystricis, D. compactus and D. steini for the future investigation of vector competence and the zoonotic potential for the Coxiella, Rickettsia and Francisella detected here, as well as their implications for the risks of tick-borne diseases among the Orang Asli communities.
The effects of moisture on ovipositional responses and larval eclosion of Aedes albopictus

Saifur RG, Dieng H, Hassan AA, Satho T, Miake F, Boots M, et al.

J Am Mosq Control Assoc, 2010 Dec;26(4):373-80.
PMID: 21290932

Moisture plays a major role in the dynamics of mosquito populations, especially those breeding in container habitats. Despite this importance, the role of moisture conditions as they affect oviposition and egg development in Aedes vectors remains largely unexplored. We investigated the effect of exposing gravid female Aedes albopictus mosquitoes and their eggs to different moisture levels (MLs) for various periods on oviposition and hatching. Overall, high-moisture substrates (HMSs; 66% and 72%) provided better environments for egg laying. The timing of initial egg laying was far longer at the lowest substrate moisture level (LSML, 25% and 41.2%) than at HMSs. The numbers of eggs laid were much lower in the drier environments. At LSMLs, gravid females retained increasing numbers of mature eggs until death, and egg retention decreased gradually with increasing ML. The HMSs also provided better environments for larval eclosion. The numbers of eggs hatched were lower at the LSML than the HSML environment. No egg hatching occurred after 1 h exposure to moisture. However, egg hatching occurred by installment, with spontaneous hatching (SH) increasing gradually with increasing ML. High-moisture conditions combined with long exposure (30 h and 48 h) favored SH. These results suggest that Ae. albopictus females can respond to better moisture conditions for increased success of embryonation and larval eclosion. This information may be useful in the colonization of floodwater Aedes species.
Fulltext Serum from Nipah Virus Patients Recognises Recombinant Viral Proteins Produced in Escherichia coli

Tiong V, Lam CW, Phoon WH, AbuBakar S, Chang LY

Jpn J Infect Dis, 2017 Jan 24;70(1):26-31.
PMID: 27169942 DOI: 10.7883/yoken.JJID.2015.501

The genes for Nipah virus (NiV) proteins were amplified from viral RNA, cloned into the plasmid pTriEx-3 Hygro, expressed, and purified using immobilized metal affinity chromatography. The recombinant N, F, and G NiV proteins (rNiV-N, rNiV-F, and rNiV-G), were successfully expressed in Escherichia coli and purified with a yield of 4, 16, and 4 mg/L, respectively. All 3 recombinant viral proteins reacted with all 19 samples of NiV-positive human sera. The rNiV-N and rNiV-G proteins were the most immunogenic. The recombinant viral proteins did not react with any of the 12 NiV-negative sera. However, serum from a patient with a late-onset relapsing NiV infection complication was found to be primarily reactive to rNiV-G only. Additionally, there is a distinctive variation in the profile of antigen-reactive bands between the sample from a case of relapsing NiV encephalitis and that of acute NiV infection. The overall findings of this study suggest that the recombinant viral proteins have the potential to be developed further for use in the detection of NiV infection, and continuous biosurveillance of NiV infection in resource-limited settings.
Vector competence of Malaysian Aedes albopictus with and without Wolbachia to four dengue virus serotypes

Joanne S, Vythilingam I, Teoh BT, Leong CS, Tan KK, Wong ML, et al.

Trop Med Int Health, 2017 09;22(9):1154-1165.
PMID: 28653334 DOI: 10.1111/tmi.12918

OBJECTIVE: To determine the susceptibility status of Aedes albopictus with and without Wolbachia to the four dengue virus serotypes.
METHODS: Two newly colonised colonies of Ae. albopictus from the wild were used for the study. One colony was naturally infected with Wolbachia while in the other Wolbachia was removed by tetracycline treatment. Both colonies were orally infected with dengue virus-infected fresh blood meal. Dengue virus load was measured using quantitative RT-PCR at four-time intervals in the salivary glands, midguts and ovaries.
RESULTS: Wolbachia did not significantly affect Malaysian Ae. albopictus dengue infection or the dissemination rate for all four dengue virus serotypes. Malaysian Ae. albopictus had the highest replication kinetics for DENV-1 and the highest salivary gland and midgut infection rate for DENV-4.
CONCLUSION: Wolbachia, which naturally exists in Malaysian Ae. albopictus, does not significantly affect dengue virus replication. Malaysian Ae. albopictus is susceptible to dengue virus infections and capable of transmitting dengue virus, especially DENV-1 and DENV-4. Removal of Wolbachia from Malaysian Ae. albopictus would not reduce their susceptibility status.
Updates on chikungunya epidemiology, clinical disease, and diagnostics

Sam IC, Kümmerer BM, Chan YF, Roques P, Drosten C, AbuBakar S

Vector Borne Zoonotic Dis, 2015 Apr;15(4):223-30.
PMID: 25897809 DOI: 10.1089/vbz.2014.1680

Chikungunya virus (CHIKV) is an Aedes-borne alphavirus, historically found in Africa and Asia, where it caused sporadic outbreaks. In 2004, CHIKV reemerged in East Africa and spread globally to cause epidemics, including, for the first time, autochthonous transmission in Europe, the Middle East, and Oceania. The epidemic strains were of the East/Central/South African genotype. Strains of the Asian genotype of CHIKV continued to cause outbreaks in Asia and spread to Oceania and, in 2013, to the Americas. Acute disease, mainly comprising fever, rash, and arthralgia, was previously regarded as self-limiting; however, there is growing evidence of severe but rare manifestations, such as neurological disease. Furthermore, CHIKV appears to cause a significant burden of long-term morbidity due to persistent arthralgia. Diagnostic assays have advanced greatly in recent years, although there remains a need for simple, accurate, and affordable tests for the developing countries where CHIKV is most prevalent. This review focuses on recent important work on the epidemiology, clinical disease and diagnostics of CHIKV.
Effect of Conductive Layer Condition on the Morphology of Anodic Aluminum Oxide Template-Assisted Indium Antimonide Nanowires

Fayyadh OA, Arifin INA, Khairudin A, Hassan J, Abubakar S, Talib ZA, et al.

J Nanosci Nanotechnol, 2020 May 01;20(5):3157-3163.
PMID: 31635660 DOI: 10.1166/jnn.2020.17386

Indium antimonide nanowires were synthesized by electrochemical deposition using anodic aluminum oxide template in the presence of gold film as conductive layers. Field emission scanning electron microscopy and energy dispersive X-ray spectrometry measurements were carried out to investigate the effect of adhesive insulated tape covered below the conductive layer. Results showed that the anodic aluminum oxide template covered with insulating tapes had better morphology with less presence of overgrown rough film on the topside of the anodic aluminum oxide template and it exhibited a smoother nanowire sidewall as compared to the uncovered ones. Additionally, the unique properties of anodic aluminum oxide were controllable pore diameter with a narrow size distribution at some intervals. It was evident from the energy dispersive X-ray spectrum that the nanowires synthesized from the covered template condition exhibited better InSb composition and stoichiometric ratio compared to the uncovered template condition.
Anaerobiospirillum succiniciproducens bacteraemia in a patient with acute lymphoblastic leukaemia

Fadzilah MN, Faizatul LJ, Hasibah MS, Sam IC, Bador MK, Gan GG, et al.

J Med Microbiol, 2009 Jan;58(Pt 1):142-143.
PMID: 19074667 DOI: 10.1099/jmm.0.004622-0

A 17-year-old man with acute lymphoblastic leukaemia had fever and diarrhoea during a febrile neutropenic episode. A spiral-shaped, Gram-negative anaerobic bacterium was isolated from blood, and confirmed as Anaerobiospirillum succiniciproducens by 16S rRNA sequencing. The patient responded to imipenem.
Fulltext Imipenem Treatment Induces Expression of Important Genes and Phenotypes in a Resistant Acinetobacter baumannii Isolate

Dhabaan GN, AbuBakar S, Cerqueira GM, Al-Haroni M, Pang SP, Hassan H

Antimicrob Agents Chemother, 2015 Dec 14;60(3):1370-6.
PMID: 26666943 DOI: 10.1128/AAC.01696-15

Acinetobacter baumannii has emerged as a notorious multidrug-resistant pathogen, and development of novel control measures is of the utmost importance. Understanding the factors that play a role in drug resistance may contribute to the identification of novel therapeutic targets. Pili are essential for A. baumannii adherence to and biofilm formation on abiotic surfaces as well as virulence. In the present study, we found that biofilm formation was significantly induced in an imipenem-resistant (Imp(r)) strain treated with a subinhibitory concentration of antibiotic compared to that in an untreated control and an imipenem-susceptible (Imp(s)) isolate. Using microarray and quantitative PCR analyses, we observed that several genes responsible for the synthesis of type IV pili were significantly upregulated in the Imp(r) but not in the Imp(s) isolate. Notably, this finding is corroborated by an increase in the motility of the Imp(r) strain. Our results suggest that the ability to overproduce colonization factors in response to imipenem treatment confers biological advantage to A. baumannii and may contribute to clinical success.
Fulltext Assessment of residual bio-efficacy and persistence of Ipomoea cairica plant extract against Culex quinquefasciatus Say mosquito

Thiagaletchumi M, Zuharah WF, Ahbi Rami R, Fadzly N, Dieng H, Ahmad AH, et al.

Trop Biomed, 2014 Sep;31(3):466-76.
PMID: 25382473 MyJurnal

Specification on residual action of a possible alternative insecticide derived from plant materials is important to determine minimum interval time between applications and the environmental persistence of the biopesticides. The objective of this study is to evaluate crude acethonilic extract of Ipomoea cairica leaves for its residual and persistence effects against Culex quinquefasciatus larvae. Wild strain of Cx. quinquefasciatus larvae were used for the purpose of the study. Two test designs, replenishment of water and without replenishment of water were carried out. For the first design, a total of 10 ml of test solution containing Ip. cairica extracts was replenished daily and replaced with 10 ml of distilled water. For the second design, treatment water was maintained at 1500 ml and only evaporated water was refilled. Larval mortality was recorded at 24 hours post-treatment after each introduction period and trials were terminated when mortality rate falls below 50%. Adult emergences from survived larvae were observed and number of survivals was recorded. For the non-replenishment design, mortality rate significantly reduced to below 50% after 28 days, meanwhile for replenishment of water declined significantly after 21 days (P < 0.05). There was no adult emergence observed up to seven days for non-replenishment and first two days for replenishment of water design. The short period of residual effectiveness of crude acethonilic extract of Ip. cairica leaves with high percentage of larval mortality on the first few days, endorses fewer concerns of having excess residues in the environment which may carry the risk of insecticide resistance and environmental pollution.
Fulltext Chikungunya virus-associated death in Malaysia

Sam IC, Kamarulzaman A, Ong GS, Veriah RS, Ponnampalavanar S, Chan YF, et al.

Trop Biomed, 2010 Aug;27(2):343-7.
PMID: 20962735

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus which causes fever, rash, and arthralgia. In the past, life-threatening complications were very rarely reported. However, during the recent worldwide outbreaks, there have been several reports of unusually severe complications and deaths. Malaysia is experiencing a nationwide outbreak of CHIKV, with over 10 000 patients affected since April 2008. We report the first case of culture-confirmed CHIKV-associated death in Malaysia, in a patient with fever, rash, acute exacerbation of pre-existing heart failure, rhabdomyolysis, and multiple organ failure. CHIKV infections may cause atypical, severe or fatal presentations.
Culturable pathogenic bacteria in ticks parasitizing farm animals and rodents in Malaysia

Loong SK, Lim FS, Khoo JJ, Lee HY, Suntharalingam C, Ishak SN, et al.

Trop Biomed, 2020 Sep 01;37(3):803-811.
PMID: 33612793 DOI: 10.47665/tb.37.3.803

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.
Insertion of single-chain variable fragment (scFv) peptide linker improves surface display of influenza hemagglutinin (HA1) on non-recombinant Lactococcus lactis

Jee PF, Chen FS, Shu MH, Wong WF, Abdul Rahim R, AbuBakar S, et al.

Biotechnol Prog, 2017 Jan;33(1):154-162.
PMID: 27802566 DOI: 10.1002/btpr.2400

Heterologous protein displayed on the surface of Lactococcus lactis using the binding domain of N-acetylmuramidase (AcmA) has a potential application in vaccine delivery. In this study, we developed a non-recombinant L. lactis surface displaying the influenza A (H1N1) 2009 hemagglutinin (HA1). Three recombinant proteins, HA1/L/AcmA, HA1/AcmA, and HA1 were overexpressed in Escherichia coli, and purified. In the binding study using flow cytometry, the HA1/L/AcmA, which contained the single-chain variable fragment (scFv) peptide linker showed significantly higher percentage of binding counts and mean fluorescence binding intensity (MFI) (51.7 ± 1.4% and 3,594.0 ± 675.9, respectively) in comparison to the HA1/AcmA without the scFv peptide linker (41.1 ± 1.5% and 1,652.0 ± 34.1, respectively). Higher amount of HA1/L/AcmA (∼2.9 × 10(4) molecules per cell) was displayed on L. lactis when compared to HA1/AcmA (∼1.1 × 10(4) molecules per cell) in the immunoblotting analysis. The HA1/L/AcmA completely agglutinated RBCs at comparable amount of protein to that of HA1/AcmA and HA1. Computational modeling of protein structures suggested that scFv peptide linker in HA1/L/AcmA kept the HA1 and the AcmA domain separated at a much longer distance in comparison to HA1/AcmA. These findings suggest that insertion of the scFv peptide linker between HA1 and AcmA improved binding of recombinant proteins to L. lactis. Hence, insertion of scFv peptide linker can be further investigated as a potential approach for improvement of heterologous proteins displayed on the surface of L. lactis using the AcmA binding domain. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:154-162, 2017.
Sera of patients with systemic lupus erythematosus cross-neutralizes dengue viruses

Zainal N, Tan KK, Johari J, Hussein H, Wan Musa WR, Hassan J, et al.

Microbiol. Immunol., 2018 Oct;62(10):659-672.
PMID: 30259549 DOI: 10.1111/1348-0421.12652

Dengue is the most prevalent mosquito-borne disease in Southeast Asia, where the incidence of systemic lupus erythematosus (SLE) is approximately 30 to 53 per 100,000. Severe dengue, however, is rarely reported among individuals with SLE. Here, whether sera of patients with SLE cross-neutralize dengue virus (DENV) was investigated. Serum samples were obtained from individuals with SLE who were dengue IgG and IgM serology negative. Neutralization assays were performed against the three major DENV serotypes. Of the dengue serology negative sera of individuals with SLE, 60%, 61% and 52% of the sera at 1/320 dilution showed more than 50% inhibition against dengue type-1 virus (DENV-1), DENV-2 and DENV-3, respectively. The neutralizing capacity of the sera was significantly greater against DENV-1 (P
Detection of a Borrelia sp. From Ixodes granulatus Ticks Collected From Rodents in Malaysia

Khoo JJ, Ishak SN, Lim FS, Mohd-Taib FS, Khor CS, Loong SK, et al.

J Med Entomol, 2018 10 25;55(6):1642-1647.
PMID: 30137379 DOI: 10.1093/jme/tjy122

The Borrelia genus consists of spirochete bacteria known to cause Lyme disease (LD) and relapsing fever in humans. Borrelia pathogens are commonly transmitted via arthropod vectors such as ticks, mites, or lice. Here, we report the molecular screening of LD group Borrelia sp. from ticks (Acari: Ixodidae) collected from rodents trapped in recreational forests and a semiurban residential area in the Selangor state in Malaysia. Of 156 adult ticks surveyed, 72 ticks were determined as positive for Borrelia sp. by polymerase chain reaction (PCR). All Borrelia PCR-positive ticks belonged to the Ixodes granulatus Supino species. Borrelia sp. was not detected in other tick species examined, including Dermacentor sp. and Amblyomma sp. ticks. Thirteen Borrelia PCR-positive tick samples were selected for further sequence analyses. Phylogenetic analyses of partial flaB gene sequences revealed that the Borrelia sp. were closely related to the LD group borreliae, Borrelia yangtzensis; a novel Borrelia genospecies reported in East Asian countries including Japan, Taiwan, and China. To our knowledge, this is the first report of Borrelia sp. related to Borrelia yangtzensis detected in Malaysia and Southeast Asia. The zoonotic potential of the Borrelia sp. reported here merits further investigation, as it may explain the previously reported serological evidence for borrelial infections in Malaysia.

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