Displaying publications 1 - 20 of 59 in total

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  1. Genus Calliophis of Asiatic coral snakes: A deficiency of venom cross-reactivity and neutralization against seven regional elapid antivenoms
    Tan CH, Liew JL, Tan KY, Tan NH
    Toxicon, 2016 Oct;121:130-133.
    PMID: 27616455 DOI: 10.1016/j.toxicon.2016.09.003
    Venoms of Calliophis bivirgata and Calliophis intestinalis exhibited moderate binding activities toward Neuro Bivalent Antivenom (Taiwan) but not the other six elapid monovalent or bivalent antivenoms available in the region. All antivenoms failed to neutralize C. bivirgata venom lethality in mice. The findings indicate the need to validate antivenom cross-reactivity with in vivo cross-neutralization, and imply that distinct antigens of Calliophis venoms should be incorporated in the production of a pan-regional poly-specific antivenom.
    Matched MeSH terms: Neutralization Tests*
  2. Fulltext Yellow fever vaccination in Malaya by subcutaneous injection and multiple puncture. Neutralizing antibody responses in persons with and without pre-existing antibody to related viruses
    Gordon Smith CE, Turner LH, Armitage P
    Bull World Health Organ, 1962;27:717-27.
    PMID: 13993152
    Because of the risk of introduction of yellow fever to South-East Asia, comparative studies were made of yellow fever vaccination in Malayans who had a high prevalence of antibody to related viruses and in volunteers without related antibody. The proportions of positive neutralizing antibody responses to subcutaneous vaccination with 17D vaccine were not significantly different between volunteers with and without heterologous antibody but the degree of antibody response was greater in those without. The ID(50) of 17D in both groups was about 5 mouse intracerebral LD(50). Multiple puncture vaccination with 17D gave a much lower response rate than subcutaneous vaccination in volunteers with heterologous antibody. In both groups subcutaneous doses of about 50 mouse intracerebral LD(50) gave larger antibody responses than higher doses. The neutralizing indices and analysis of results were calculated by a method based on the survival time of the mice. This method, which has advantages over that of Reed & Muench, is fully described in an annex to this paper.
    Matched MeSH terms: Neutralization Tests*
  3. Current status of diagnostic methods for henipavirus
    Tamin A, Rota PA
    Dev Biol (Basel), 2013;135:139-45.
    PMID: 23689891 DOI: 10.1159/000189236
    Hendra virus (HeV) and Nipah virus (NiV) are the causative agents of emerging transboundary animal disease in pigs and horses. They also cause fatal disease in humans. NiV has a case fatality rate of 40 - 100%. In the initial NiV outbreak in Malaysia in 1999, about 1.1 million pigs had to be culled. The economic impact was estimated to be approximately US$450 million. Worldwide, HeV has caused more than 60 deaths in horses with 7 human cases and 4 deaths. Since the initial outbreak, HeV spillovers from Pteropus bats to horses and humans continue. This article presents a brief review on the currently available diagnostic methods for henipavirus infections, including advances achieved since the initial outbreak, and a gap analysis of areas needing improvement.
    Matched MeSH terms: Neutralization Tests/methods; Neutralization Tests/veterinary*
  4. Cross neutralisation of Southeast Asian cobra and krait venoms by Indian polyvalent antivenoms
    Leong PK, Tan NH, Fung SY, Sim SM
    Trans R Soc Trop Med Hyg, 2012 Dec;106(12):731-7.
    PMID: 23062608 DOI: 10.1016/j.trstmh.2012.07.009
    Cross neutralisation of venoms by antivenom raised against closely-related species has been well documented. The spectrum of paraspecific protection of antivenom raised against Asiatic Naja and Bungarus (krait) venoms, however, has not been fully investigated. In this study, we examined the cross neutralisation of venoms from common Southeast Asian cobras and kraits by two widely used polyvalent antivenoms produced in India: Vins Polyvalent Antivenom (VPAV) and Bharat Polyvalent Antivenom (BPAV), using both in vitro and in vivo mouse protection assays. BPAV was only moderately effective against venoms of N. kaouthia (Thailand) and N. sumatrana, and either very weakly effective or totally ineffective against the other cobra and krait venoms. VPAV, on the other hand, neutralised effectively all the Southeast Asian Naja venoms tested, as well as N. naja, B. candidus and Ophiophagus hannah venoms, but the potency ranges from effective to weakly effective. In an in vivo rodent model, VPAV also neutralised the lethality of venoms from Asiatic Naja and B. candidus. In anesthetised rat studies, both antivenoms effectively protected against the N. kaouthia venom-induced cardio-respiratory depressant and neuromuscular blocking effects. Overall, our results suggest that VPAV could be used as alternative antivenom for the treatment of elapid envenomation in Southeast Asian regions including Malaysia, Thailand and certain regions of Indonesia.
    Matched MeSH terms: Neutralization Tests/methods; Neutralization Tests/statistics & numerical data
  5. Lanjan virus, a new agent isolated from Dermacentor auratus in Malaya
    Tan DS, Smith CE, McMahon DA, Bowen ET
    Nature, 1967 Jun 10;214(5093):1154-5.
    PMID: 4964058
    Matched MeSH terms: Neutralization Tests
  6. Autochthonous spread of DENV-3 genotype III in Malaysia mitigated by pre-existing homotypic and heterotypic immunity
    Tan KK, Nellis S, Zulkifle NI, Sulaiman S, AbuBakar S
    Epidemiol Infect, 2018 10;146(13):1635-1641.
    PMID: 29860959 DOI: 10.1017/S0950268818001425
    Dengue virus type 3 genotype III (DENV-3/III) is widely distributed in most dengue-endemic regions. It emerged in Malaysia in 2008 and autochthonously spread in the midst of endemic DENV-3/I circulation. The spread, however, was limited and the virus did not cause any major outbreak. Spatiotemporal distribution study of DENV-3 over the period between 2005 and 2011 revealed that dengue cases involving DENV-3/III occurred mostly in areas without pre-existing circulating DENV-3. Neutralisation assays performed using sera of patients with the respective infection showed that the DENV-3/III viruses can be effectively neutralised by sera of patients with DENV-3 infection (50% foci reduction neutralisation titres (FRNT50) > 1300). Sera of patients with DENV-1 infection (FRNT50 ⩾ 190), but not sera of patients with DENV-2 infection (FRNT50 ⩽ 50), were also able to neutralise the virus. These findings highlight the possibility that the pre-existing homotypic DENV-3 and the cross-reacting heterotypic DENV-1 antibody responses could play a role in mitigating a major outbreak involving DENV-3/III in the Klang Valley, Malaysia.
    Matched MeSH terms: Neutralization Tests
  7. Fulltext Serological Evidence of Japanese Encephalitis Virus Circulation in Asian Children From Dengue-Endemic Countries
    Nealon J, Taurel AF, Yoksan S, Moureau A, Bonaparte M, Quang LC, et al.
    J Infect Dis, 2019 Jan 09;219(3):375-381.
    PMID: 30165664 DOI: 10.1093/infdis/jiy513
    Background: Japanese encephalitis virus (JEV) is a zoonotic, mosquito-borne flavivirus, distributed across Asia. Infections are mostly mild or asymptomatic, but symptoms include neurological disorders, sequelae, and fatalities. Data to inform control strategies are limited due to incomplete case reporting.

    Methods: We used JEV serological data from a multicountry Asian dengue vaccine study in children aged 2-14 years to describe JEV endemicity, measuring antibodies by plaque reduction neutralization test (PRNT50).

    Results: A total 1479 unvaccinated subjects were included. A minimal estimate of pediatric JEV seroprevalence in dengue-naive individuals was 8.1% in Indonesia, 5.8% in Malaysia, 10.8% in the Philippines, and 30.7% in Vietnam, translating to annual infection risks varying from 0.8% (in Malaysia) to 5.2% (in Vietnam). JEV seroprevalence and annual infection estimates were much higher in children with history of dengue infection, indicating cross-neutralization within the JEV PRNT50 assay.

    Conclusions: These data confirm JEV transmission across predominantly urban areas and support a greater emphasis on JEV case finding, diagnosis, and prevention.

    Matched MeSH terms: Neutralization Tests
  8. Fulltext Isolation of ancestral sylvatic dengue virus type 1, Malaysia
    Teoh BT, Sam SS, Abd-Jamil J, AbuBakar S
    Emerg Infect Dis, 2010 Nov;16(11):1783-5.
    PMID: 21029545 DOI: 10.3201/eid1611.100721
    Ancestral sylvatic dengue virus type 1, which was isolated from a monkey in 1972, was isolated from a patient with dengue fever in Malaysia. The virus is neutralized by serum of patients with endemic DENV-1 infection. Rare isolation of this virus suggests a limited spillover infection from an otherwise restricted sylvatic cycle.
    Matched MeSH terms: Neutralization Tests
  9. Chikungunya virus of Asian and Central/East African genotypes in Malaysia
    Sam IC, Chan YF, Chan SY, Loong SK, Chin HK, Hooi PS, et al.
    J Clin Virol, 2009 Oct;46(2):180-3.
    PMID: 19683467 DOI: 10.1016/j.jcv.2009.07.016
    BACKGROUND: Chikungunya virus (CHIKV) of the Central/East African genotype has caused large outbreaks worldwide in recent years. In Malaysia, limited CHIKV outbreaks of the endemic Asian and imported Central/East African genotypes were reported in 1998 and 2006. Since April 2008, an unprecedented nationwide outbreak has affected Malaysia.
    OBJECTIVE: To study the molecular epidemiology of the current Malaysian CHIKV outbreak, and to evaluate cross-neutralisation activity of serum from infected patients against isolates of Asian and Central/East African genotypes.
    STUDY DESIGN: Serum samples were collected from 83 patients presenting in 2008, and tested with PCR for the E1 gene, virus isolation, and for IgM. Phylogenetic analysis was performed on partial E1 gene sequences of 837bp length. Convalescent serum from the current outbreak and Bagan Panchor outbreak (Asian genotype, 2006) were tested for cross-neutralising activity against representative strains from each outbreak.
    RESULTS: CHIKV was confirmed in 34 patients (41.0%). The current outbreak strain has the A226V mutation in the E1 structural protein, and grouped with Central/East African isolates from recent global outbreaks. Serum cross-neutralisation activity against both Central/East African and Asian genotypes was observed at titres from 40 to 1280.
    CONCLUSIONS: The CHIKV strain causing the largest Malaysian outbreak is of the Central/East African genotype. The presence of the A226V mutation, which enhances transmissibility of CHIKV by Aedes albopictus, may explain the extensive spread especially in rural areas. Serum cross-neutralisation of different genotypes may aid potential vaccines and limit the effect of future outbreaks.
    Matched MeSH terms: Neutralization Tests/methods
  10. Fulltext Yellow fever vaccination in Malaya by subcutaneous injection and multiple puncture. Haemagglutinin-inhibiting antibody responses in persons with and without pre-existing antibody
    Gordon Smith CE, McMahon DA, Turner LH
    Bull World Health Organ, 1963;29:75-80.
    PMID: 14043754
    In view of the risk of introduction of yellow fever into South-East Asia, comparative studies have been made of yellow fever vaccination in Malayan volunteers with a high prevalence of antibody to related viruses and in volunteers without related antibody. In a previous paper the neutralizing antibody responses of these volunteers were reported. The present paper describes the haemagglutinin-inhibiting (HI) antibody responses of the same groups of volunteers and discusses the relationship of these responses to the neutralizing antibody responses.The HI responses to yellow fever following vaccination closely paralleled the neutralizing antibody responses whether vaccination was subcutaneous or by multiple puncture. Volunteers with a high level of YF HI antibody due to infection with other group B viruses were found to be less likely to show a significant YF HI response than those without antibody. 90% of HI responses could be detected by the 21st day after vaccination.As with neutralizing antibody responses, volunteers given vaccine doses of 50-500 mouse intracerebral LD(50) subcutaneously gave greater responses than those given higher doses.
    Matched MeSH terms: Neutralization Tests*
  11. Differential Diagnosis of Flavivirus Infections in Horses Using Viral Envelope Protein Domain III Antigens in Enzyme-Linked Immunosorbent Assay
    Piyasena TBH, Setoh YX, Hobson-Peters J, Prow NA, Bielefeldt-Ohmann H, Khromykh AA, et al.
    Vector Borne Zoonotic Dis, 2017 12;17(12):825-835.
    PMID: 29083957 DOI: 10.1089/vbz.2017.2172
    In Australia, infection of horses with the West Nile virus (WNV) or Murray Valley encephalitis virus (MVEV) occasionally results in severe neurological disease that cannot be clinically differentiated. Confirmatory serological tests to detect antibody specific for MVEV or WNV in horses are often hampered by cross-reactive antibodies induced to conserved epitopes on the envelope (E) protein. This study utilized bacterially expressed recombinant antigens derived from domain III of the E protein (rE-DIII) of MVEV and WNV, respectively, to determine whether these subunit antigens provided specific diagnostic markers of infection with these two viruses. When a panel of 130 serum samples, from horses with known flavivirus infection status, was tested in enzyme-linked immunosorbent assay (ELISA) using rE-DIII antigens, a differential diagnosis of MVEV or WNV was achieved for most samples. Time-point samples from horses exposed to flavivirus infection during the 2011 outbreak of equine encephalitis in south-eastern Australia also indicated that the rE-DIII antigens were capable of detecting and differentiating MVEV and WNV infection in convalescent sera with similar sensitivity and specificity to virus neutralization tests and blocking ELISAs. Overall, these results indicate that the rE-DIII is a suitable antigen for use in rapid immunoassays for confirming MVEV and WNV infections in horses in the Australian context and warrant further assessment on sensitive, high-throughput serological platforms such as multiplex immune assays.
    Matched MeSH terms: Neutralization Tests/veterinary
  12. A solid-phase blocking ELISA for detection of antibodies to Nipah virus
    Kashiwazaki Y, Na YN, Tanimura N, Imada T
    J Virol Methods, 2004 Nov;121(2):259-61.
    PMID: 15381364
    A monoclonal antibody (MAb) based solid-phase blocking ELISA was developed for detection of antibodies to Nipah virus. The ELISA was designed to detect remaining antigens on the plate with anti-Nipah MAb conjugate after the reaction with sample serum, and enabled simple procedure, detection of neutralizing antibody to Nipah virus, and application of samples from different animal species. Forty of 200 swine reference sera examined were positive by the ELISA, of which thirty seven were found positive by serum neutralization test. Sera from a total of 131 fruit bats captured in Malaysia were also tested and all found negative by the both tests. It is considered that the solid-phase blocking ELISA can be used as a screening test for Nipah virus infection followed by the serum neutralization test as confirmatory test.
    Matched MeSH terms: Neutralization Tests/standards
  13. Detection of influenza A and B neutralizing antibodies in vaccinated ferrets and macaques using specific biotin-streptavidin conjugated antibodies
    Sirskyj D, Weltzin R, Golshani A, Anderson D, Bozic J, Diaz-Mitoma F, et al.
    J Virol Methods, 2010 Feb;163(2):459-64.
    PMID: 19913054 DOI: 10.1016/j.jviromet.2009.11.014
    Several critical factors of an influenza microneutralization assay, utilizing a rapid biotin-streptavidin conjugated system for detecting influenza virus subtypes A and B, are addressed within this manuscript. Factors such as incubation times, amount of virus, cell seeding, sonication, and TPCK trypsin were evaluated for their ability to affect influenza virus neutralization in a microplate-based neutralization assay using Madin-Darby canine kidney (MDCK) cells. It is apparent that the amount of virus used in the assay is the most critical factor to be optimized in an influenza microneutralization assay. Results indicate that 100xTCID(50) of influenza A/Solomon Islands/03/2006 (H1N1) virus overloads the assay and results in no, to low, neutralization, in both ferret and macaque sera, respectively, whereas using 6xTCID(50) resulted in significantly improved neutralization. Conversely, strong neutralization was observed against 100xTCID(50) of B/Malaysia/2506/04 virus. In this manuscript the critical factors described above were optimized and the results indicate that the described biotin-streptavidin conjugated influenza microneutralization assay is a rapid and robust method for detecting the presence of functional, influenza virus-neutralizing antibodies.
    Matched MeSH terms: Neutralization Tests/methods*
  14. Fulltext Screening of pig sera for antibodies to Japanese encephalitis virus using a dot enzyme immunoassay and IgM capture ELISA: comparison with the hemagglutination inhibition and plaque reduction neutralization tests
    Cardosa MJ, Hah FL, Choo BH, Padmanathan S
    Southeast Asian J Trop Med Public Health, 1993 Sep;24(3):472-6.
    PMID: 8160055
    A dot enzyme immunoassay for determination of antibodies to Japanese encephalitis virus was designed for use as a field technique for the surveillance of Japanese encephalitis virus activity among domestic pigs. The test was compared with the neutralization test and the hemagglutination inhibition test and found to be more sensitive than the hemagglutination inhibition test and comparable to the neutralization test in sensitivity but more simple to perform than either the neutralization or the hemagglutination inhibition tests. An IgM capture ELISA for the determination of JEV specific porcine IgM was also utilized to determine current infection rates in pigs. The tests which do not involve the determination of specific IgM are better used for testing sentinel animals for providing clues as to the rate of transmission of JEV among pigs. IgM tests determining acute infection are less likely to be useful unless animals are tested very frequently or if a great number of animals are tested at any one time.
    Matched MeSH terms: Neutralization Tests*
  15. Cross neutralization of common Southeast Asian viperid venoms by a Thai polyvalent snake antivenom (Hemato Polyvalent Snake Antivenom)
    Leong PK, Tan CH, Sim SM, Fung SY, Sumana K, Sitprija V, et al.
    Acta Trop, 2014 Apr;132:7-14.
    PMID: 24384454 DOI: 10.1016/j.actatropica.2013.12.015
    Snake envenomation is a serious public health threat in many rural areas of Asia and Africa. Antivenom has hitherto been the definite treatment for snake envenomation. Owing to a lack of local production of specific antivenom, most countries in these regions fully depend on foreign supplies of antivenoms. Often, the effectiveness of the imported antivenoms against local medically important species has not been validated. This study aimed to assess cross-neutralizing capacity of a recently developed polyvalent antivenom, Hemato Polyvalent Snake Antivenom (HPAV), against venoms of a common viper and some pit vipers from Southeast Asia. Neutralisation assays showed that HPAV was able to effectively neutralize lethality of the common Southeast Asian viperid venoms examined (Calloselasma, Crytelytrops, Popeia, and Daboia sp.) except for Tropidolaemus wagleri venom. HPAV also effectively neutralized the procoagulant and hemorrhagic activities of all the venoms examined, corroboratively supporting the capability of HPAV in neutralizing viperid venoms which are principally hematoxic. The study also indicated that HPAV fully prevented the occurrence of hematuria and proteinuria in mice envenomed with Thai Daboia siamensis venom but was only partially effective against venoms of Myanmar D. siamensis. Thus, HPAV appears to be useful against its homologous venoms and venoms from Southeast Asian viperids including several medically important pit vipers belonging to the Trimeresurus complex. Nevertheless, the effectiveness of HPAV as a paraspecific antivenom for treatment of viperid envenomation in Southeast Asian region requires further assessment from future clinical trials.
    Matched MeSH terms: Neutralization Tests
  16. Japanese B encephalitis in a horse
    Chong Sue Kheng, Teoh Kim Chee, Marchette NJ, Garcia R, Rudnick A, Coughlan RF
    Aust. Vet. J., 1968 Jan;44(1):23-5.
    PMID: 5689238
    Matched MeSH terms: Neutralization Tests
  17. Isolation of Zika virus from Aedes aegypti mosquitoes in Malaysia
    Marchette NJ, Garcia R, Rudnick A
    Am J Trop Med Hyg, 1969 May;18(3):411-5.
    PMID: 4976739
    Matched MeSH terms: Neutralization Tests
  18. Cross reactivity and lethality neutralization of venoms of Indonesian Trimeresurus complex species by Thai Green Pit Viper Antivenom
    Tan CH, Liew JL, Tan NH, Ismail AK, Maharani T, Khomvilai S, et al.
    Toxicon, 2017 Dec 15;140:32-37.
    PMID: 29051104 DOI: 10.1016/j.toxicon.2017.10.014
    Arboreal pit vipers of the Trimeresurus complex group are medically important species in Indonesia (west of Wallace's line), but there is no specific antivenom produced in the country for treating related envenomation. Instead, the exiting trivalent Indonesian antivenom, Biosave® Serum Anti Bisa Ular (SABU, indicated for envenoming by Malayan pit viper, Javan spitting cobra and banded krait) is often misused to treat Trimeresus envenoming resulting in poor therapeutic outcome. Here, we investigated the cross-reactivity and neutralization capability of Thai Green Pit Viper Antivenom (GPVAV) against the venoms of four Indonesian Trimeresurus species. Consistently, the venoms of Trimeresurus (Trimeresurus) insularis, Trimeresurus (Trimeresurus) purpureomaculatus, Trimeresurus (Parias) hageni and Trimeresurus (Craspedocephalus) puniceus of Indonesia showed stronger immunoreactivity on ELISA to GPVAV than to Biosave®. The findings correlated with in vivo neutralization results, whereby GPVAV was far more effective than Biosave® in cross-neutralizing the lethality of the venoms by a potency of at least 13 to 80 times higher. The efficacy of GPVAV is partly attributable to its cross-neutralization of the procoagulant effect of the venoms, thereby mitigating the progression of venom-induced consumptive coagulopathy. The paraspecific effectiveness of GPVAV against Trimeresurus species envenoming in Indonesia await further clinical investigation.
    Matched MeSH terms: Neutralization Tests
  19. Evaluating the physicochemical properties and efficacy of recently expired and aged antivenom products from Thailand and Taiwan
    Tan KY, Liew ST, Tan QY, Abdul-Rahman FN, Azmi NI, Sim SM, et al.
    Toxicon, 2019 Mar 15;160:55-58.
    PMID: 30797900 DOI: 10.1016/j.toxicon.2019.02.010
    Gel filtration chromatography and gel electrophoresis revealed minimal protein degradation in lyophilized antivenoms which were 2-year expired (Hemato Polyvalent, Neuro Polyvalent; Thailand) and 18-year expired (Hemato Bivalent, Neuro Bivalent; Taiwan). All expired antivenoms retained immunological binding activity, and were able to neutralize the hemotoxic or neurotoxic as well as lethal effects of the homologous snake venoms. The findings show that antivenoms under proper storage conditions may remain relatively stable beyond the indicated shelf life.
    Matched MeSH terms: Neutralization Tests
  20. Thai Russell's viper monospecific antivenom is immunoreactive and effective in neutralizing the venom of Daboia siamensis from Java, Indonesia
    Lingam TMC, Tan KY, Tan CH
    Toxicon, 2019 Oct;168:95-97.
    PMID: 31254600 DOI: 10.1016/j.toxicon.2019.06.227
    Daboia siamensis monovalent antivenom (DSMAV, Thailand) exhibited comparable immunoreactivity toward the venoms of eastern Russell's vipers from Thailand and Indonesia. It also effectively neutralized the procoagulant and lethal effects of both venoms, showing high potency. The Indonesian heterologous trivalent antivenom SABU (Serum Anti Bisa Ular), however, has very weak immunoreactivity and it failed to neutralize the Russell's viper venoms. DSMAV appears to be the appropriate choice of antivenom to treat Russell's viper envenoming.
    Matched MeSH terms: Neutralization Tests
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