32 research outputs found

    Possible occurrence of a genetic bottleneck in dengue serotype 2 viruses between the 1980 and 1987 epidemic seasons in Bangkok Thailand

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    Cocirculation of two genetic subtypes of denguc serotype 2 viruses was first observed in the 1980 epidemic season in Thailand. To further delineate the evolutionary history and the contribution of these subtypes to subsequent epidemics, we determined the envelope glycoprotcin gene sequence of 20 dengue serotype 2 viruses isolated from infected patients during 1987 and compared them with those derived from earlier years. Subtype ifia strains represented the majority (18 of 19) of dengue type 2 viruses derived from Bangkok metropolitan area, whereas all three strains from a province in the northeastern region belonged to subtype Ilib, indicating uneven local distni bution of dengue subtypes within the same year. Three types of sequence variation were identified in both subtypes: substitutions that were unique to individual strains; substitutions that were shared among all subtype HIa on Ilib viruses of both the 1980 and 1987 epidemics; and those that were shared only among all subtypes lila or IIlb viruses of the 1987 epidemic, but were absent from the corresponding subtypes of 1980. While the first and second types of substitution were indicative of the most recent random mutations and previous mutations that had been fixed in virus populations, respectively, the third type suggested possible occurrence of a genetic bottleneck and subsequent expan sion of one or a limited number of subtype lila strains in Bangkok between 1980 and 1987. Immunobbot analysis of intracellular NS1 antigen with anti-NS1 monocbonal antibodies also revealed antigenic heterogeneity of the NSl protein that correlated with the subdivision based on envelope protein variation

    Enteric and non-enteric adenoviruses associated with acute gastroenteritis in pediatric patients in Thailand, 2011 to 2017.

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    Human adenovirus (HAdV) is known to be a common cause of diarrhea in children worldwide. Infection with adenovirus is responsible for 2-10% of diarrheic cases. To increase a better understanding of the prevalence and epidemiology of HAdV infection, a large scale and long-term study was needed. We implemented a multi-year molecular detection and characterization study of HAdV in association with acute gastroenteritis in Chiang Mai, Thailand from 2011 to 2017. Out of 2,312 patients, HAdV was detected in 165 cases (7.2%). The positive rate for HAdV infection was highest in children of 1 and 2 years of age compared to other age groups. HAdV subgroup C (40.6%) was the most prevalent, followed by subgroups F (28.5%), B (20.6%), A and D (4.8% each), and E (0.6%). Of these, HAdV-F41 (22.4%), HAdV-C2 (18.2%), HAdV-B3 (15.2%), and HAdV-C1 (13.3%) were the most common genotypes detected. HAdV infection occurred throughout the year with a higher detection rate between May and July. In conclusion, our study demonstrated the infection rate, seasonal distribution and genotype diversity of HAdV infection in children with diarrhea in Chiang Mai, Thailand over a period of 7 year. Not only enteric adenovirus (F40 and F41) but also non-enteric adenovirus (B3, C1, C2) may play an important role in gastroenteritis in this area. The information will be beneficial for the prevention and control of HAdV outbreaks in the future

    Evidence of Intragenic Recombination in G1 Rotavirus VP7 Genes▿

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    The G1 rotavirus is the most widespread genotype causing acute gastroenteritis in children. In an attempt to investigate the occurrence of intragenic recombination, 131 complete coding region sequences of VP7 genes of the G1 rotaviruses in GenBank were examined. Three hitherto-unreported intragenic recombinant rotaviruses were identified. It was noteworthy that two different types (interlineage and intersublineage) of intragenic recombination in rotaviruses were also found. This is the first report to demonstrate the existence of intragenic recombinations between interlineage and intersublineage in G1 rotaviruses

    Epidemiology of Enterovirus Genotypes in Association with Human Diseases

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    Enteroviruses (EVs) are well-known causes of a wide range of infectious diseases in infants and young children, ranging from mild illnesses to severe conditions, depending on the virus genotypes and the host’s immunity. Recent advances in molecular surveillance and genotyping tools have identified over 116 different human EV genotypes from various types of clinical samples. However, the current knowledge about most of these genotypes, except for those of well-known genotypes like EV-A71 and EV-D68, is still limited due to a lack of comprehensive EV surveillance systems. This limited information makes it difficult to understand the true burden of EV-related diseases globally. Furthermore, the specific EV genotype associated with diseases varies according to country, population group, and study period. The same genotype can exhibit different epidemiological features in different areas. By integrating the data from established EV surveillance systems in the USA, Europe, Japan, and China, in combination with other EV infection studies, we can elaborate a better understanding of the distribution of prevalent EV genotypes and the diseases associated with EV. This review analyzed the data from various EV surveillance databases and explored the EV seroprevalence and the association of specific EV genotypes with human diseases
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