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Studies into the immunopathogenesis and laboratory diagnosis of dengue haemorrhagic fever

Pang T

Ann Acad Med Singap, 1987 Oct;16(4):612-6.
PMID: 2895602

Studies were carried out into the immunopathogenesis and laboratory diagnosis of dengue virus infections. Using an experimental system it was shown that cell-mediated immunity (CMI), as measured by delayed-type hypersensitivity (DTH) was induced in mice infected with dengue virus. The nature of the DTH response satisfies most criteria for a classical DTH reaction. In addition, it was also shown that infection with dengue virus causes a transient immunosuppression as measured by the immune response to other, unrelated antigens. With regard to the laboratory diagnosis of dengue infections, it was found that mosquito cells were a sensitive system for the isolation of dengue viruses and that the success of isolation was related to the antibody content of the serum. A new method for the rapid isolation of dengue viruses was also developed involving the intracerebral inoculation of mosquito larvae. By the use of this method viral antigens can be detected as early as 2-3 days after specimen inoculation. The significance of these findings in relation to the immunopathogenesis, prevention and control of disease syndromes due to dengue viruses is discussed.

Matched MeSH terms: Culicidae
Construction of an infectious molecular clone of Japanese encephalitis virus genotype V and its derivative subgenomic replicon capable of expressing a foreign gene

Ishikawa T, Abe M, Masuda M

Virus Res, 2015 Jan 2;195:153-61.
PMID: 25451067 DOI: 10.1016/j.virusres.2014.10.010

Japanese encephalitis virus (JEV) genotype V was originally isolated in Malaysia in 1952 and has long been restricted to the area. In 2009, sudden emergence of the genotype V in China and Korea was reported, suggesting expansion of its geographical distribution. Although studies on the genotype V are becoming more important, they have been limited partly due to lack of its infectious molecular clone. In this study, a plasmid carrying cDNA corresponding to the entire genome of JEV Muar strain, which belongs to genotype V, in the downstream of T7 promoter was constructed. Electroporation of viral RNA transcribed by T7 RNA polymerase (T7RNAP) in vitro from the plasmid led to production of progeny viruses both in mammalian and mosquito cells. Also, transfection of the infectious clone plasmid into mammalian cells expressing T7RNAP transiently or stably was demonstrated to generate infectious progenies. When the viral structural protein genes were partially deleted from the full-length cDNA, the subgenomic RNA transcribed in vitro from the modified plasmid was shown to replicate itself in mammalian cells as a replicon. The replicon carrying the firefly luciferase gene in place of the deleted structural protein genes was also shown to efficiently replicate itself and express luciferase in mammalian cells. Compared with the replicon derived from JEV genotype III (Nakayama strain), the genotype V-derived replicon appeared to be more tolerant to introduction of a foreign gene. The infectious clone and the replicons constructed in this study may serve as useful tools for characterizing JEV genotype V.

Matched MeSH terms: Culicidae
Fulltext Pathological findings in a mouse model of Japanese encephalitis infected via the footpad

Fu, Tzeh Long, Ong, Kien Chai, Wong, Kum Thong

Neurology Asia, 2015;20(4):349-354.
MyJurnal

We have developed and characterised a mouse model of Japanese encephalitis virus (JEV) infection via
footpad inoculation in order to better mimic viral transmission by mosquito bites. Two-week-old and
5-week-old mice consistently developed signs of infection such as ruffled fur, weight loss, hunchback
posture, tremors, mask-like facies and occasionally, hindlimb paralysis at 4 days post infection (dpi)
and 11-13 dpi, respectively. Most of the animals died within 24 to 48 hours following the onset of signs
of infection, with mortalities of 100% and 33.3% in 2-week-old and 5-week-old mice, respectively.
Mild meningitis and variable parenchymal inflammation with formation of microglial nodules, focal
necrosis and neuronophagia, and perivascular cuffing by inflammatory cells were observed in the
caudate nucleus, putamen, thalamus, cerebral cortex, brainstem, and spinal cord. Viral antigens/RNA
were demonstrated by immunohistochemisty and in situ hybridization, respectively, in most of these
areas as well as in the hippocampus and cerebellum, albeit more focally. The pathological findings in
this mouse model were generally similar to human Japanese encephalitis (JE) and other established JE
models but perhaps, compared to other JEV mouse models, it demonstrates lethal encephalitic infection
more consistently. We believe that our mouse model should be useful to study the pathogenesis of JE,
and for testing anti-viral drugs and vaccines

Matched MeSH terms: Culicidae
Fulltext Immunological surveys of arbovirus infections in South-East Asia, with special reference to dengue, chikungunya, and Kyasanur Forest disease

Rao TR

Bull World Health Organ, 1971;44(5):585-91.
PMID: 4400821

Serological surveys have been widely used in South-East Asia to determine the presence and activity of arboviruses. The haemagglutination-inhibition test has been most frequently employed but complement-fixation and neutralization tests have also been used in some investigations.Although virus isolations provide the most conclusive evidence, they can be carried out in a few specialized centres only, and serological surveys are very important for studying the distribution of arboviruses.The surveys have shown that group B arboviruses (principally all four types of dengue, Japanese encephalitis, and West Nile) are widely prevalent. Dengue and Japanese encephalitis viruses are more widespread than West Nile virus, which was not known previously to extend east of India although recent survyes have shown that its range extends to Burma. Japanese encephalitis is frequent in most of South-East Asia but in India is found mainly in eastern and south-eastern parts of the country. Kyasanur Forest disease (KFD) and Langat viruses are the only tick-borne group B arboviruses definitely known to occur in the region, the former in India, the latter in Malaysia. KFD virus has been isolated only from a small focus in Mysore, although human and animal sera containing neutralizing antibodies to this virus have been found sporadically in widely scattered areas. Among the group A arboviruses, chikungunya and Sindbis have been detected in serological surveys, but the former has not yet been found in Malaysia.

Matched MeSH terms: Culicidae
Efficacy of diethylcarbamazine and pirimiphos-methyl residual spraying in controlling brugian filariasis

Chang MS, Ho BC, Chan KL

Trop. Med. Parasitol., 1991 Jun;42(2):95-102.
PMID: 1680246

A control programme against subperiodic brugian filariasis was implemented in three villages, (Kg. Ampungan, Kg. Sebangkoi and Kg. Sebamban) in Sarawak, Malaysia. In Kampong Ampungan, the mass administration of diethylcarbamazine (DEC-citrate) combined with residual house spraying of pirimiphos-methyl reduced microfilarial rate to 8% of the pre-treatment level and microfilarial density (MfD50) to 44% of the pre-treatment level over a period of four years. In Kampong Sebangkoi and Kampong Sebamban, where only mass DEC therapy was applied, the microfilarial rate and MfD50 declined distinctly in the second blood survey but increased gradually in two subsequent follow-up blood surveys. In Kg, Ampungan, we observed a significant reduction of infective biting rate (88.3%), infection rate (62.5%) and transmission potential (88.1%) of Mansonia bonneae at the fourth spray round. The corresponding reduction rates in Kg. Sebangkoi and Kg. Sebamban were 35.3%, 26.7%, 42.2% and 24%, 30.8% and 15.4% respectively. The biting density of the vector was reduced by 79.8% indoors and 31.8% outdoors at the sprayed village, while only a slight decrease in densities (17.9% indoors and 12.4% outdoors) was observed at the unsprayed village. Bioassay tests revealed that pirimiphos-methyl had a substantial fumigant effect on the vector. The integrated control measure in controlling subperiodic brugian filariasis is discussed.

Matched MeSH terms: Culicidae/parasitology
Diversity and natural selection of Merozoite surface Protein-1 in three species of human malaria parasites: Contribution from South-East Asian isolates

Goh XT, Lim YAL, Lee PC, Nissapatorn V, Chua KH

Mol Biochem Parasitol, 2021 07;244:111390.
PMID: 34087264 DOI: 10.1016/j.molbiopara.2021.111390

The present study aimed to examine the genetic diversity of human malaria parasites (i.e., P. falciparum, P. vivax and P. knowlesi) in Malaysia and southern Thailand targeting the 19-kDa C-terminal region of Merozoite Surface Protein-1 (MSP-119). This region is essential for the recognition and invasion of erythrocytes and it is considered one of the leading candidates for asexual blood stage vaccines. However, the genetic data of MSP-119 among human malaria parasites in Malaysia is limited and there is also a need to update the current sequence diversity of this gene region among the Thailand isolates. In this study, genomic DNA was extracted from 384 microscopy-positive blood samples collected from patients who attended the hospitals or clinics in Malaysia and malaria clinics in Thailand from the year 2008 to 2016. The MSP-119 was amplified using PCR followed by bidirectional sequencing. DNA sequences identified in the present study were subjected to Median-joining network analysis with sequences of MSP-119 obtained from GenBank. DNA sequence analysis revealed that PfMSP-119 of Malaysian and Thailand isolates was not genetically conserved as high number of haplotypes were detected and positive selection was prevalent in PfMSP-119, hence questioning its suitability to be used as a vaccine candidate. A novel haplotype (Q/TNG/L) was also detected in Thailand P. falciparum isolate. In contrast, PvMSP-119 was highly conserved, however for the first time, a non-synonymous substitution (A1657S) was reported among Malaysian isolates. As for PkMSP-119, the presence of purifying selection and low nucleotide diversity indicated that it might be a potential vaccine target for P. knowlesi.

Matched MeSH terms: Culicidae/parasitology
Fever and rash in a returning traveller

Kumar N, Lewis DJ

BMJ, 2012;344:e2400.
PMID: 22496299 DOI: 10.1136/bmj.e2400
Matched MeSH terms: Culicidae
Biological treatment of fishery washing water using Bacillus sphaericus coupled with production of spores that are toxic to mosquito larvae

Ariff AB, Rosfarizan M, Sobri MA, Karim MI

Environ Technol, 2001 Jun;22(6):697-704.
PMID: 11482390

Research was undertaken to investigate the treatment of fishery washing water using Bacillus sphaericus, and to recover the spores for subsequent use as bioinsecticide to control the population of mosquitoes. This treatment method could reduce pollution due to organic matter by decreasing the value of Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) by about 85% and 92%, respectively. The maximum concentration of spores (83.3 x 10(7) spores ml(-1)) using normal concentration of filtered fishery washing water was only about 27% lower than that obtained in fermentation using 0.25% (w/v) yeast extract. The larvicidal activity of the spores produced in fermentation using fishery washing water to Culex quinquefaciatus, as measured by LD50 after 48 h, was almost the same as the larvicidal activity of spores obtained from fermentation using yeast extract.

Matched MeSH terms: Culicidae
Clostridium bifermentans serovar malaysia: sporulation, biogenesis of inclusion bodies and larvicidal effect on mosquito

Charles JF, Nicolas L, Sebald M, de Barjac H

Res. Microbiol., 1990 7 1;141(6):721-33.
PMID: 1980958

Sporulation of Clostridium bifermentans serovar malaysia, which has a larvicidal activity towards mosquitoes, was examined by electron microscopy. Parasporal inclusion bodies lacking a crystalline structure were first detected at t5 (5 h after the end of exponentional growth). Also, the presence of "brush-bottle"-like appendages appearing first at t5 was noted; these remained attached to the spores when released after sporangium lysis. Larvicidal activity assayed on Anopheles stephensi larvae appeared at t0 and increased rapidly to a maximum between t5 and t8. However, a decrease in bacterial toxicity occurred with sporangium lysis.

Matched MeSH terms: Culicidae
Filariasis in Sabah, East Malaysia

Barclay R

Ann Trop Med Parasitol, 1969 Dec;63(4):473-88.
PMID: 4393668
Matched MeSH terms: Culicidae
Fulltext Is it safe to prescribe triple drugs therapy for lymphatic filariasis infection in Epidermolysis Bullosa patient? a case report

S. Izuddin, Nur Dalila Zakaria, Nur L. A., Omar K. K.

Malaysian Journal of Medicine and Health Sciences, 2019;15(106):85-85.
MyJurnal

Introduction:Filariasis is an endemic infection in tropical and subtropical countries. The disease is caused by para-sites from the group filarodidae. Epidermolysis Bullosa, on the other hand is a group of rare genetic skin diseases that characterize by skin blister and erode facilely. Due to rarity of Epidermolysis Bullosa and uncommon occurrence of Filariasis, there is extremely limited case or paper reporting on safety profile of medication that are used to treat Filariasis patient with underlying Epidermolysis Bullosa.Serious adverse event that is anticipated in this cohort of patient are Stevens-Johnson syndrome and Mazotti reaction. Case description: Surveillance activity is necessary in high endemic localities in Sabah in order to control the spread of this mosquitoes-borne disease. The available tool is Brugia RapidTM kit, a test kit that detects filarial antibodies.A 13 year-old boy with underlying Epidemolysis Bullosa Simplex was detected during surveillance activities. It was further confirmed with night blood on microscopic slide that depicted high density of parasite (microfilaria count: 31). The WHO specifically exempted the following groups from the treatment - children under 5 years of age; pregnant women; and seriously ill individuals i.e. those who are having acute or chronic illness that makes them too sick or weak to get out of bed; and those with an illness who are life-dependent on medical intervention. This is because ingestion of the medications can result in adverse events due to the destruction of killed parasites. No guideline is available for treatment of lymphatic filariasis in rare genetic disorders. Conclusion: The recommended dosage for IDA is Ivermectin 3mcg/kg, Diethylcarbamazine 6mg/kg and Albendazole 400mg for positive patient yearly. Patient was admitted in hospital for observation treatment with the suggested dose. From the case study it shows it is safe to treat this cohort patient. However, it is advisable to treat such rare cases by case basis and in comparison to others where treatment is given in the community this patients should be treat in more control environment such in the hospital.

Matched MeSH terms: Culicidae
Emergence of Getah Virus Infection in Horse With Fever in China, 2018

Lu G, Ou J, Ji J, Ren Z, Hu X, Wang C, et al.

Front Microbiol, 2019;10:1416.
PMID: 31281304 DOI: 10.3389/fmicb.2019.01416

Getah virus (GETV) is a mosquito-borne virus that was first determined in Malaysia in 1955, and can infect humans and multiple other mammals. GETV infection in horses has been reported in Japan and India, and causes great economic losses. In China, GETV has been identified in mosquitoes, pigs, foxes, and cattle with a wide geographical distribution, but has not been detected in horses. In August 2018, a sudden onset of fever was observed in racehorse in an equestrian training center in Guangdong Province in southern China. Blood samples were collected from the sick horse, and PCR/RT-PCR analysis was performed to screen for equine viral pathogens associated with fever. The results indicated that the samples were GETV RNA positive. After RT-PCR, sequencing, and assembly, the genome of the first Chinese horse-derived GETV strain, GZ201808, was obtained. Compared with the genome sequences of other GETV strains, twelve unique nucleotide substitutions were observed in GZ201808. The genome of GZ201808 had the highest genetic identity (99.6%) with AH9192, which was detected in pigs in China in 2017. Phylogenetic analysis indicated that GZ201808 clustered in Group III, and was located in an independent branch distant from other horse-derived GETV strains, indicating a unique evolutionary pattern of GZ201808. This study first determined and described the disease course of horse infected with GETV in China, sequenced and characterized the genome of the field horse-derived GETV strain, and therefore presented an unequivocal report of GETV infection in horses in China.

Matched MeSH terms: Culicidae
Fulltext Preliminary review on the prevalence, proportion, geographical distribution, and characteristics of naturally acquired Plasmodium cynomolgi infection in mosquitoes, macaques, and humans: a systematic review and meta-analysis

Kotepui M, Masangkay FR, Kotepui KU, Milanez GJ

BMC Infect Dis, 2021 Mar 12;21(1):259.
PMID: 33711940 DOI: 10.1186/s12879-021-05941-y

BACKGROUND: Plasmodium cynomolgi is a simian malaria parasite that has been reported as a naturally acquired human infection. The present study aims to systematically review reports on naturally acquired P. cynomolgi in humans, mosquitoes, and macaques to provide relevant data for pre-emptive surveillance and preparation in the event of an outbreak of zoonotic malaria in Southeast Asia.
METHODS: The protocol of the systematic review was registered at PROSPERO with approval ID CRD42020203046. Three databases (Web of Science, Scopus, and MEDLINE) were searched for studies reporting the prevalence of P. cynomolgi infections in Southeast Asian countries between 1946 and 2020. The pooled prevalence or pooled proportion of P. cynomolgi parasitemia in humans, mosquitoes, and macaques was estimated using a random-effects model. Differences in the clinical characteristics of P. cynomolgi infections were also estimated using a random-effects model and presented as pooled odds ratios (ORs) or mean differences (MDs) with 95% confidence intervals (CIs).
RESULTS: Thirteen studies reporting on the prevalence of naturally acquired P. cynomolgi in humans (3 studies, 21 cases), mosquitoes (3 studies, 28 cases), and macaques (7 studies, 334 cases) were included. The results demonstrated that the pooled proportion of naturally acquired P. cynomolgi in humans was 1% (95% CI, 0.1%, I2, 0%), while the pooled proportion of P. cynomolgi infecting mosquitoes was 18% (95% CI, 10-26%, I2, 32.7%). The pooled prevalence of naturally acquired P. cynomolgi in macaques was 47% (95% CI, 27-67%, I2, 98.3%). Most of the cases of naturally acquired P. cynomolgi in humans were reported in Cambodia (62%) and Malaysia (38%), while cases of P. cynomolgi in macaques were reported in Malaysia (35.4%), Singapore (23.2%), Indonesia (17.3%), Philippines (8.5%), Laos (7.93%), and Cambodia (7.65%). Cases of P. cynomolgi in mosquitoes were reported in Vietnam (76.9%) and Malaysia (23.1%).
CONCLUSIONS: This study demonstrated the occurrence of naturally acquired P. cynomolgi infection in humans, mosquitoes, and macaques. Further studies of P. cynomolgi in asymptomatic human cases in areas where vectors and natural hosts are endemic are extensively needed if human infections with P. cynomolgi do become public health problems.

Matched MeSH terms: Culicidae
Fulltext Evaluation of female Aedes aegypti proteome via LC-ESI-MS/MS using two protein extraction methods

Shettima A, Ishak IH, Abdul Rais SH, Abu Hasan H, Othman N

PeerJ, 2021;9:e10863.
PMID: 33717682 DOI: 10.7717/peerj.10863

Background: Proteomic analyses have broadened the horizons of vector control measures by identifying proteins associated with different biological and physiological processes and give further insight into the mosquitoes' biology, mechanism of insecticide resistance and pathogens-mosquitoes interaction. Female Ae. aegypti ingests human blood to acquire the requisite nutrients to make eggs. During blood ingestion, female mosquitoes transmit different pathogens. Therefore, this study aimed to determine the best protein extraction method for mass spectrometry analysis which will allow a better proteome profiling for female mosquitoes.
Methods: In this present study, two protein extractions methods were performed to analyze female Ae. aegyti proteome, via TCA acetone precipitation extraction method and a commercial protein extraction reagent CytoBusterTM. Then, protein identification was performed by LC-ESI-MS/MS and followed by functional protein annotation analysis.
Results: The CytoBusterTM reagent gave the highest protein yield with a mean of 475.90 µg compared to TCA acetone precipitation extraction showed 283.15 µg mean of protein. LC-ESI-MS/MS identified 1,290 and 890 proteins from the CytoBusterTM reagent and TCA acetone precipitation, respectively. When comparing the protein class categories in both methods, there were three additional categories for proteins identified using CytoBusterTM reagent. The proteins were related to scaffold/adaptor protein (PC00226), protein binding activity modulator (PC00095) and intercellular signal molecule (PC00207). In conclusion, the CytoBusterTM protein extraction reagent showed a better performance for the extraction of proteins in term of the protein yield, proteome coverage and extraction speed.

Matched MeSH terms: Culicidae
Fulltext An unusual case of concurrent dengue and malaria infection

Hong, Eric Qiu Weng, Cheo, Seng Wee, Low, Qin Jian

Borneo Journal of Medical Sciences, 2021;15(1):57-60.
MyJurnal

Dengue and malaria infections are common mosquito-borne infectious diseases in tropical and subtropical regions. The clinical manifestations of dengue and malaria often mimic each other, causing the predicament of early diagnosis without laboratory investigations. Concurrent dengue and malaria infection are often rare scenarios when both diseases occur in a particular patient at the same time. A high index of suspicion is therefore required to establish an early diagnosis to ensure complete success in its management. This case report is about concurrent dengue and malaria infection in a 54-year-old Pakistani man who presented with high-grade fever for three days before admission. On examination, he was febrile (38.8°C) with no other findings. His blood investigations were positive for NS1 antigen and IgM but negative for IgG. His peripheral blood film revealed the presence of Plasmodium vivax. He was treated for dengue fever with supportive management and started with oral Riamet (artemether and lumefantrine) along with oral primaquine 30 mg daily for two weeks’ duration. Following treatment, the patient demonstrated progressive clinical improvement and was subsequently discharged back to the community clinic for the continuation of care.

Matched MeSH terms: Culicidae
Fulltext Plasmodium-a brief introduction to the parasites causing human malaria and their basic biology

Sato S

J Physiol Anthropol, 2021 Jan 07;40(1):1.
PMID: 33413683 DOI: 10.1186/s40101-020-00251-9

Malaria is one of the most devastating infectious diseases of humans. It is problematic clinically and economically as it prevails in poorer countries and regions, strongly hindering socioeconomic development. The causative agents of malaria are unicellular protozoan parasites belonging to the genus Plasmodium. These parasites infect not only humans but also other vertebrates, from reptiles and birds to mammals. To date, over 200 species of Plasmodium have been formally described, and each species infects a certain range of hosts. Plasmodium species that naturally infect humans and cause malaria in large areas of the world are limited to five-P. falciparum, P. vivax, P. malariae, P. ovale and P. knowlesi. The first four are specific for humans, while P. knowlesi is naturally maintained in macaque monkeys and causes zoonotic malaria widely in South East Asia. Transmission of Plasmodium species between vertebrate hosts depends on an insect vector, which is usually the mosquito. The vector is not just a carrier but the definitive host, where sexual reproduction of Plasmodium species occurs, and the parasite's development in the insect is essential for transmission to the next vertebrate host. The range of insect species that can support the critical development of Plasmodium depends on the individual parasite species, but all five Plasmodium species causing malaria in humans are transmitted exclusively by anopheline mosquitoes. Plasmodium species have remarkable genetic flexibility which lets them adapt to alterations in the environment, giving them the potential to quickly develop resistance to therapeutics such as antimalarials and to change host specificity. In this article, selected topics involving the Plasmodium species that cause malaria in humans are reviewed.

Matched MeSH terms: Culicidae
Changing Geographic Distribution of Japanese Encephalitis Virus Genotypes, 1935-2017

Gao X, Liu H, Li X, Fu S, Cao L, Shao N, et al.

Vector Borne Zoonotic Dis, 2019 Jan;19(1):35-44.
PMID: 30207876 DOI: 10.1089/vbz.2018.2291

Japanese encephalitis virus (JEV) is a representative virus of the JEV serogroup in genus Flavivirus, family Flaviviridae. JEV is a mosquito-borne virus that causes Japanese encephalitis (JE), one of the most severe viral encephalitis diseases in the world. JEV is divided into five genotypes (G1-G5), and each genotype has its own distribution pattern. However, the distribution of different JEV genotypes has changed markedly in recent years. JEV G1 has replaced G3 as the dominant genotype in the traditional epidemic areas in Asia, while G3 has spread from Asia to Europe and Africa and caused domestic JE cases in Africa. G2 and G5, which were endemic in Malaysia, exhibited great geographical changes as well. G2 migrated southward and led to prevalence of JE in Australia, while G5 emerged in China and South Korea after decades of silence. Along with these changes, JE occurred in some non-traditional epidemic regions as an emerging infectious disease. The regional changes in JEV pose a great threat to human health, leading to huge disease burdens. Therefore, it is of great importance to strengthen the monitoring of JEV as well as virus genotypes, especially in non-traditional epidemic areas.

Matched MeSH terms: Culicidae
Antiviral and virucidal activities of sulphated polysaccharides against Japanese encephalitis virus

Nor Rashid N, Yusof R, Rothan HA

Trop Biomed, 2020 Sep 01;37(3):713-721.
PMID: 33612784 DOI: 10.47665/tb.37.3.713

Japanese encephalitis virus (JEV), a member of the family Flaviviridae, causes severe neurological disorders in humans. JEV infections represent one of the most widely spread mosquito-borne diseases, and therefore, it has been considered as an endemic disease. An effective antiviral drug is still unavailable to treat JEV, and current drugs only provide supportive treatment to alleviate the symptoms and stabilize patients' conditions. This study was designed to evaluate the antiviral activity of the sulphated polysaccharides "Carrageenan," a linear sulphated polysaccharide that is extracted from red edible seaweeds against JEV replication in vitro. Viral inactivation, attachment, and post-infection assays were used to determine the mode of inhibition of Carrageenan. Virus titters after each application were evaluated by plaque formation assay. MTT assay was used to determine the 50% cytotoxic concentration (CC50), and ELISA-like cell-based assay and immunostaining and immunostaining techniques were used to evaluate the 50% effective concentration (EC50). This study showed that Carrageenan inhibited JEV at an EC50 of 15 µg/mL in a dose-dependent manner with CC50 more than 200 µg/mL in healthy human liver cells (WRL68). The mode of inhibition assay showed that the antiviral effects of Carrageenan are mainly due to their ability to inhibit the early stages of virus infection such as the viral attachment and the cellular entry stages. Our investigation showed that Carrageenan could be considered as a potent antiviral agent to JEV infection. Further experimental and clinical studies are needed to investigate the potential applications of Carrageenan for clinical intervention against JEV infection.

Matched MeSH terms: Culicidae
Arbovirus infections in Sarawak, October 1968-February 1970: GETAH virus isolations from mosquitoes

Simpson DI, Way HJ, Platt GS, Bowen ET, Hill MN, Kamath S, et al.

Trans R Soc Trop Med Hyg, 1975;69(1):35-8.
PMID: 238314

14 strains of Getah virus were isolated from a variety of mosquito species collected in Sarawak between October 1968 and February 1970. Ten strains were isolated from C. tritaeniorhynchus 7 of them at K. Tijirak. Single strains were isolated from C. gelidus, C. pseudovishnui, M. bonneae/dives and Aanopheles species. 6 of the isolates were obtained in October 1968 when Japanese encephalitis, Tembusu and Sindbis viruses were also very active. The available evidence suggest that Getah virus in Sarawak is maintained in a cycle similar to that of Japanese encephalitis virus and involves C. tritaeniorhynchus, C. gelidus and domestic pigs.

Matched MeSH terms: Culicidae
Fulltext Evidence of West Nile virus infection in migratory and resident wild birds in west coast of peninsular Malaysia

Ain-Najwa MY, Yasmin AR, Omar AR, Arshad SS, Abu J, Mohammed HO, et al.

One Health, 2020 Dec;10:100134.
PMID: 32405525 DOI: 10.1016/j.onehlt.2020.100134

West Nile virus (WNV) is a zoonotic mosquito-borne flavivirus that is harbored and amplified by wild birds via the enzootic transmission cycle. Wide range of hosts are found to be susceptible to WNV infection including mammals, amphibians and reptiles across the world. Several studies have demonstrated that WNV was present in the Malaysian Orang Asli and captive birds. However, no data are available on the WNV prevalence in wild birds found in Malaysia. Therefore this study was conducted to determine the serological and molecular prevalence of WNV in wild birds in selected areas in the West Coast of Peninsular Malaysia. Two types of wild birds were screened, namely migratory and resident birds in order to explore any possibility of WNV transmission from the migratory birds to the resident birds. Thus, a cross-sectional study was conducted at the migratory birds sanctuary located in Kuala Gula, Perak and Kapar, Selangor by catching 163 migratory birds, and 97 resident birds from Kuala Gula and Parit Buntar, Perak at different time between 2016 and 2017 (Total, n = 260). Blood and oropharyngeal swabs were collected for serological and molecular analysis, respectively. Serum were screened for WNV antibodies using a commercial competitive ELISA (c-ELISA) (ID Screen® West Nile Competition Multi-species ELISA, ID VET, Montpellier, France) and cross-reactivity towards Japanese Encephalitis virus (JEV) was also carried out using the JEV-double antigen sandwich (DAS) ELISA. Oropharyngeal swabs were subjected to one-step RT-PCR to detect WNV RNA, in which positive reactions were subsequently sequenced. WNV seropositive rate of 18.71% (29/155) at 95% CI (0.131 to 0.260) and molecular prevalence of 15.2% (16/105) at 95% CI (0.092 to 0.239) were demonstrated in migratory and resident wild birds found in West Coast Malaysia. Phylogenetic analyses of the 16 WNV isolates found in this study revealed that the local strains have 99% similarity to the strains from South Africa and were clustered under lineage 2. Evidence of WNV infection in resident and migratory birds were demonstrated in this study. As a summary, intervention between migratory birds, resident birds and mosquitoes might cause the introduction and maintenance of WNV in Malaysia, however the assumption could be further proven by studying the infection dynamics in the mosquitoes present in the studied areas.

Matched MeSH terms: Culicidae

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