An overview of dengue viral infection circulating in Pakistan

Background & objectives: Dengue virus (DENV) is an RNA virus that infects approximately 2.5 billion people around the world. The incidence of dengue fever has rapidly increased at an alarming rate in the last few years and has affected thousands of people in Pakistan. This review explores the prevalence, serotypes and pathogenesis of dengue virus circulating in Pakistan. Methods: A systematic review of observational studies published between 1994 and December 2019 was performed. All records of the confirmed outbreak of dengue fever in Pakistan were reviewed and articles containing no primary data were excluded. Results: Four identified serotypes of dengue virus (DENV 1-4) circulate in different regions of the world causing epidemics. The most prevalent serotype, which is still epidemic and dominant in Pakistan, is DENV-2. Many factors like over-population, rapid urbanization, travelling, lack of vector control in dengue endemic areas and inadequate health-care are responsible of dynamic and huge raise of dengue in Pakistan. Interpretation & conclusion: Currently there is no specific treatment for prevention of dengue virus. Recently some antiviral compounds were being tested to eradicate this disease. There is a need to develop an efficient and safe vaccine for all four serotypes to combat dengue viral infection globally and particularly in Pakistan.

Development of a sandwich ELISA for detecting 3AB non-structural protein of foot-and-mouth disease virus / 生物工程学报

Antigenic purity is important for quality control of the foot-and-mouth (FMD) whole virus inactivated vaccine. The recommended method for evaluation the antigenic purity of FMD vaccine is to check the serum conversion to non-structural protein (NSP) 3AB antibody after 2 to 3 times inoculation of animals with inactivated vaccine. In this study, we developed a quantitative ELISA to detect the amount of residual 3AB in vaccine antigen, to provide a reference to evaluate the antigenic purity of FMD vaccine. Monoclonal antibody (Mab) of NSP 3A and HRP-conjugated Mab of NSP 3B were used to establish a sandwich ELISA to quantify the NSP 3AB in vaccine antigen of FMD. Purified NSP 3AB expressed in Escherichia coli was serially diluted and detected to draw the standard curve. The detectable limit was determined to be the lowest concentration of standard where the ratio of its OD value to OD blank well was not less than 2.0. Results: The OD value was linearly corelated with the concentration of 3AB protein within the range between 4.7 and 600 ng/mL. The correlation coefficient R² is greater than 0.99, and the lowest detectable limit is 4.7 ng/mL. The amount of 3AB protein in non-purified inactivated virus antigen was detected between 9.3 and 200 ng/mL depending on the 12 different virus strains, whereas the amount of 3AB in purified virus antigen was below the lowest detectable limit. The amount of 3AB in 9 batches of commercial FMD vaccine antigens was between 9.0 and 74 ng/mL, whereas it was below the detectable limit in other 24 batches of commercial vaccine antigens. Conclusion: the sandwich ELISA established in this study is specific and sensitive to detect the content of 3AB protein in vaccine antigen of FMD, which will be a useful method for evaluation of the antigenic purity and quality control of FMD inactivated vaccine.

Characterisation of a rare, reassortant human G10P[14] rotavirus strain detected in Honduras

BACKGROUND Although first detected in animals, the rare rotavirus strain G10P[14] has been sporadically detected in humans in Slovenia, Thailand, United Kingdom and Australia among other countries. Earlier studies suggest that the strains found in humans resulted from interspecies transmission and reassortment between human and bovine rotavirus strains. OBJECTIVES In this study, a G10P[14] rotavirus genotype detected in a human stool sample in Honduras during the 2010-2011 rotavirus season, from an unvaccinated 30-month old boy who reported at the hospital with severe diarrhea and vomiting, was characterised to determine the possible evolutionary origin of the rare strain. METHODS For the sample detected as G10P[14], 10% suspension was prepared and used for RNA extraction and sequence independent amplification. The amplicons were sequenced by next-generation sequencing using the Illumina MiSeq 150 paired end method. The sequence reads were analysed using CLC Genomics Workbench 6.0 and phylogenetic trees were constructed using PhyML version 3.0. FINDINGS The next generation sequencing and phylogenetic analyses of the 11-segmented genome of the G10P[14] strain allowed classification as G10-P[14]-I2-R2-C2-M2-A3-N2-T6-E2-H3. Six of the genes (VP1, VP2, VP3, VP6, NSP2 and NSP4) were DS-1-like. NSP1 and NSP5 were AU-1-like and NSP3 was T6, which suggests that multiple reassortment events occurred in the evolution of the strain. The phylogenetic analyses and genetic distance calculations showed that the VP7, VP4, VP6, VP1, VP3, NSP1, NSP3 and NSP4 genes clustered predominantly with bovine strains. NSP2 and VP2 genes were most closely related to simian and human strains, respectively, and NSP5 was most closely related to a rhesus strain. MAIN CONCLUSIONS The genetic characterisation of the G10P[14] strain from Honduras suggests that its genome resulted from multiple reassortment events which were possibly mediated through interspecies transmissions.

Chikungunya infection: A potential re-emerging global threat

Infectious diseases are indeed a lifelong threat to everyone irrespective of age, sex, lifestyle and socio-economic status. The infectious diseases have persisted among the prominent causes of death globally. Recently, re-emergence of Chikungunya viral infection harmed many in Asian and African countries. Chikungunya was considered as a major threat in developing and under-developed countries; the recent epidemiological outbreak of Chikungunya in La Reunion urges the global researchers to develop effective vaccine against this viral disease. In this review, Chikungunya, pathogenesis and epidemiology were briefly described.

Chikungunya infection: A potential re-emerging global threat

Infectious diseases are indeed a lifelong threat to everyone irrespective of age, sex, lifestyle and socio-economic status. The infectious diseases have persisted among the prominent causes of death globally. Recently, re-emergence of Chikungunya viral infection harmed many in Asian and African countries. Chikungunya was considered as a major threat in developing and under-developed countries; the recent epidemiological outbreak of Chikungunya in La Reunion urges the global researchers to develop effective vaccine against this viral disease. In this review, Chikungunya, pathogenesis and epidemiology were briefly described.

A experiência brasileira na erradicação da febre aftosa e o emprego do sistema I-ELISA 3ABC/EITB para certificação sanitária de bovinos e bubalinos / The Brazilian experience in the eradication of foot-and-mouth disease and the use of I-ELISA 3ABC/EITB system for sanitary certification of bovine and buffaloes

A vacinação contra febre aftosa é ferramenta eficaz para erradicação e prevenção da doença, contudo, a presença de proteínas não capsidais (PNC) na vacina, produzidas durante a multiplicação viral, tem sido o principal problema, visto que sua presença dificulta as ações de vigilância, cuja busca se baseia na detecção de anticorpos contra essas proteínas para diferenciar animal vacinado de infectado. Por esse motivo, o Ministério da Agricultura, Pecuária e Abastecimento publicou em 2008 a Instrução Normativa nº 50 (IN 50), que incluiu no controle da qualidade da vacina a pesquisa de anticorpos contra as PNC, para avaliar a retirada dessas proteínas. Considerando a interferência vacinal, objetivou-se avaliar a frequência de bovinos reagentes às PNC, analisada pelo sistema I-ELISA 3ABC/EITB, no Laboratório de Viroses de Bovídeos do Instituto Biológico de São Paulo, no período de 2002 a 2012. Dos 34.705 bovinos examinados, observou-se que a proporção de reagentes às PNC aumentou com a idade, evidenciando aumento da frequência de reagentes em animais que receberam maior número de vacinações, indicando interferência da vacinação na resposta às proteínas. Quando comparados antes e após a publicação da IN 50, observa-se diminuição da reatividade, com redução, em 2010, de quase a metade em relação a 2007, e ainda maior quando comparado com o período 2002 a 2006. Isso demonstra a efetividade da purificação da vacina em resposta ao cumprimento da IN 50, embora permaneça alguma sororreatividade em bovinos com múltiplas vacinações. O sistema I-ELISA 3ABC/EITB demonstrou ser uma ótima ferramenta para impedir a movimentação de possíveis portadores do vírus oriundos de rebanhos vacinados, desde que seja considerado todo o contexto sanitário e epidemiológico.(AU)

Vaccination against foot-and-mouth disease is an effective tool for eradication and prevention of this disease. However, the presence of non-capsidal proteins (NCP) in the vaccine, produced during viral replication, has been the main problem, since their presence hamper the vigilance as its relies on the detection of antibodies against NCP to differentiate vaccinated from infected animals. Therefore, the Brazilian Ministry of Agriculture, Livestock and Supply published the Normative Instruction 50 (IN 50) that included the detection of antibodies against the NCP to evaluate the removal of these proteins. Considering the vaccine interference, this paper aimed to evaluate the frequency of reagents to NCP, analyzed by I-ELISA 3ABC/EITB system in the Laboratory of Bovine Viruses (LVB), Biological Institute (IB), São Paulo, SP, Brazil, from 2002 to 2012. Of the 34,705 cattle examined, it was observed that the proportion of reagents to NCP increased with age, indicating increased frequency of reagents in animals that received more vaccines, showing interference of proteins in response to vaccination. When compared before and after the publication of IN 50, there was decreased reactivity, with reduction in 2010, of nearly half compared to 2007, and even higher when compared with 2002 to 2006. This shows the effectiveness of the purification of the vaccine in response to the implementation of IN 50, although it remains some seroreactivity in cattle with multiple vaccinations. The I-ELISA 3ABC/EITB system proved to be a great tool to prevent the movement of possible carriers of the virus derived from vaccinated herds, provided that all sanitary and epidemiological context are taken in consideration.(AU)