Enterovirus genotypes causing hand foot and mouth disease in Shanghai, China: a molecular epidemiological analysis

Abstract

Background: A rapid expansion of hand, foot, and mouth disease (HFMD) outbreaks has occurred and caused deaths in China in recent years, but little is known about the other etiologic agents except enterovirus 71 (EV71) and coxsackievirus A 16 (CA16). The objective of this study is to determine the genotype compositions of enterovirus causing HFMD in Shanghai and identify any associations between enterovirus types and clinical manifestations.

Methods: Stool specimens were collected from patients hospitalized for treatment of HFMD, from May 2010 to April 2011. Enterovirus was detected by reverse transcription PCR and directly genotyped by sequencing the PCR products. Phylogenetic analysis was based on the VP1 partial gene.

Results: Of 290 specimens, 277 (95.5%) tested positive for enterovirus. The major genotypes were EV71 (63.8%), CA10 (9.0%), CA6 (8.3%), CA16 (6.9%), CA12 (2.4%), and CA4 (1.4%). The EV71 strains belonged to the C4a subtype and CA16 belonged to the B subtype. CA6 was closely related to strains detected in Japan, Taiwan and China, and CA10, CA12 and CA4 were phylogenetically similar to other strains circulating in China. Mean hospital stays and the prevalence of complications in patients with EV71 infection were higher than those in patients in CA6, CA10 or CA16 infection (P < 0.05 for all comparisons). Children with CA12 infection were the youngest, and most likely have the highest risk of complications when compared to the other non-EV71 infection groups.

Conclusions: This study demonstrated a diversified pathogen compositions attributing to HFMD and clinical symptoms differing in enterovirus genotypes. It deserves our attention as early identification of enterovirus genotypes is important for diagnosis and treatment of HFMD patients.

Figure 1

Phylogenetic analysis with the neighbor-joining method based on the alignment of the 468 nucleotide VP1 gene of 163 Shanghai EV71 strains. The 59 reference strains were obtained from the US National Center for Biotechnology Information’s Genbank.

Figure 2

Phylogenetic analysis based on the alignment of the 488 nucleotide VP1 gene of 15 Shanghai CA16 strains. The 25 reference strains were obtained from the US National Center for Biotechnology Information’s Genbank.

Figure 3

Phylogenetic analysis based on the alignment of the 248 nucleotide VP1 gene of 23 Shanghai CA6 strains. The 28 reference strains were obtained from the US National Center for Biotechnology Information’s Genbank.

Figure 4

Phylogenetic analysis based on the alignment of the 355 nucleotide VP1 gene of 23 Shanghai CA10 strains. The 25 reference strains were obtained from the US National Center for Biotechnology Information’s Genbank.