ABSTRACT
BACKGROUND/PURPOSE: In recent years, coxsackievirus B3 (CV-B3) has been determined as a dominant enterovirus serotype that may cause severe complications in patients. Since 2008 in Taiwan, some enterovirus isolates have been regarded as untypeable [by employing commercial immunofluorescence assay (IFA) kits]. In 2012, the number of isolates increased. Genetic sequence analysis further confirmed that CV-B3 was present in most of the untypeable viruses. METHODS: Isolates of CV-B3 were collected for basic local alignment search tool (BLAST) analysis and for phylogenetic analyses, based on VP1 gene sequences. In addition, the Taiwan Centers for Disease Control (Taiwan CDC) developed an in-house indirect IFA using polyclonal antibodies (e.g., rabbit antisera) for diagnosis. The sensitivity and specificity were both evaluated by testing 61 reference enteroviruses and 307 local enteroviruses that were isolated between 1998 and 2010. RESULTS: Based on the results of the BLAST and phylogenetic analyses, five main genogroups (i.e., GI-GV) were classified and the reference strains in Taiwan in previous years were primarily clustered in the GV-A subgenogroup. However, the 15 CV-B3 isolates recently analyzed in this study were classified in four different groups: GIII, GIV, GV-A, and GV-B. Among these 15 isolates, all 10 isolates in the GV-B group were initially reported as untypeable nonpolio enteroviruses when using commercial kits. The conditions of the in-house indirect IFA were optimized by checkerboard titration, thereby resulting in a sensitivity of 100% and a specificity of 98.5%. CONCLUSION: This is the first report describing the phylogenetic relatedness of recent CV-B3 strains in Taiwan. An indirect IFA kit was developed by the Taiwan CDC for detecting CV-B3 viruses that are untypeable by commercial IFA kits.
Subject(s)
Coxsackievirus Infections/diagnosis , Coxsackievirus Infections/virology , Enterovirus B, Human/classification , Enterovirus B, Human/genetics , Fluorescent Antibody Technique, Indirect/methods , Enterovirus B, Human/isolation & purification , Genotype , Humans , Phenotype , Phylogeny , Sensitivity and Specificity , Sequence Analysis, DNA , Taiwan , Viral Structural Proteins/geneticsABSTRACT
BACKGROUND: Human enterovirus 71 (EV-71) is known of having caused numerous outbreaks of hand-foot-mouth disease, and other clinical manifestations globally. In 2008, 989 EV-71 strains were isolated in Taiwan. RESULTS: In this study, the genetic and antigenic properties of these strains were analyzed and the genetic diversity of EV-71 subgenogroups surfacing in Taiwan was depicted, which includes 3 previously reported subgenogroups of C5, B5, and C4, and one C2-like subgenogroup. Based on the phylogenetic analyses using their complete genome nucleotide sequences and neutralization tests, the C2-like subgenogroup forms a genetically distinct cluster from other subgenogroups, and the antisera show a maximum of 128-fold decrease of neutralization titer against this subgenogroup. In addition, the subgenogroup C4 isolates of 2008 were found quite similar genetically to the Chinese strains that caused outbreaks in recent years and thus they should be carefully watched. CONCLUSIONS: Other than to be the first report describing the existence of C2-like subgenogroup of EV-71 in Taiwan, this article also foresees a potential of subgenogroup C4 outbreaks in Taiwan in the near future.
Subject(s)
Enterovirus A, Human/classification , Enterovirus A, Human/genetics , Enterovirus Infections/virology , Genetic Variation , Adolescent , Adult , Antibodies, Neutralizing/blood , Antibodies, Viral/blood , Child , Child, Preschool , Cluster Analysis , Enterovirus A, Human/immunology , Enterovirus A, Human/isolation & purification , Female , Genome, Viral , Humans , Infant , Infant, Newborn , Male , Molecular Sequence Data , Neutralization Tests , Phylogeny , RNA, Viral/genetics , Sequence Analysis, DNA , Taiwan , Young AdultABSTRACT
We describe the development and evaluation of an indirect immunofluorescence assay (IFA) kit for rapid and sensitive detection of coxsackievirus A2, -4, -5, -6, and -10. This IFA kit was determined to have 95.9 to 100% sensitivity and 95.8 to 97.2% specificity. It also proved to be beneficial in reducing the number of enteroviruses that are untypeable in the clinical virology laboratory.
