Objective The (sero) type distribution and molecular characteristics of enteroviruses (EV) associated with herpangina (HA) in Shenzhen were investigated to provide scientific basis for HA control and prevention.
Methods A total of 314 clinical specimens from 157 HA patients, including 157 feces specimens and 157 throat swabs, were collected between 2017 and 2018. EV types were determined using real-time reverse transcription polymerase chain reaction (RT-PCR), RT nested PCR, and sequencing. VP1 sequences were analyzed using bioinformatics programs.
Results Ten EV types were detected in 126 EV-positive HA patients (80.30%, 126/157). The most predominant pathogen was coxsackievirus A10 (CVA10) (19.70%, 31/157), followed by CVA4 (17.80%, 28/157), CVA6 (15.30%, 24/157) and CVA2 (10.80%, 17/157). Other pathogens detected included CVA5 (4.50%, 7/157), CVA16 (3.20%, 5/157), EV-A71 (1.30%, 2/157), CVA8 (0.60%, 1/157), CVB5 (0.60%, 1/157) and echovirus 11 (E11) (0.60%, 1/157). One patient co-infected CVA4 with CVA10. The predominant pathogens were CVA2 and CVA6 in 2017, but CVA10 and CVA4 became predominant in 2018. There was no statistically significant difference (χ2=0.019, P=0.892) between the pathogen detection rates of feces specimens and throat swabs. Molecular phylogeny based on the complete VP1 gene indicated that all CVA10 strains from this study were assigned to genotype C2 . All CVA4 strains except for one strain which was assigned to genotype C5 belonged to genotype C2. All CVA6 strains except for one strain which grouped in a previously uncharacterized clade were assigned to sub-genotype D3a. All CVA2 strains belonged to genotype D2.
Conclusion Both feces specimens and throat swabs are suitable for EV RNA testing for HA. The main pathogens were CVA10, CVA4, CVA6 and CVA2 in HA patients from 2017 to 2018 in Shenzhen, China. A majority of strains belonged to the genotypes which were prevalent in China. And individual strain grouped in an uncommon genotype or clade.
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