Phylogenetic and molecular characterization of coxsackievirus A24 variant isolates from a 2010 acute hemorrhagic conjunctivitis outbreak in Guangdong, China

Abstract

BackgroundAcute hemorrhagic conjunctivitis is a common disease in China. As a notifiable disease, cases are registered by ophthalmologists on the AHC surveillance system. An AHC outbreak caused by CA24v was observed in Guangdong Province in 2007 by the National Disease Supervision Information Management System. Three years later, a larger outbreak occurred in Guangdong during the August-October period (2010). To characterize the outbreak and compare the genetic diversity of CA24v, which was determined to be the cause of the outbreak, the epidemiology and the molecular characterization of CA24v were analyzed in this study.ResultsA total of 69,635 cases were reported in the outbreak. 73.5% of index cases originated from students, children in kindergarten and factory workers, with the ≦ 9 age group at the highest risk. The male to female ratio was 1.84:1 among 0-19 years. 56 conjunctival swabs were collected to identify the causative agent from five cities with the AHC outbreak. 30 virus strains were isolated, and two of the genomes had the highest identity values (95.8%) with CA24v genomes. Four CA24v genotypes were identified by phylogenetic analysis for the VP1 and 3C regions. CA24v which caused the outbreak belonged to genotype IV. Furthermore, full nucleotide sequences for four representative isolates in 2010 and 2007 were determined and compared. 20 aa mutations, two nt insertions and one nt deletion were observed in the open reading frame, with 5'- and 3'- UTR respectively between them.ConclusionsCA24v was determined to be the pathogen causing the outbreak and belongs to genotype IV. VP1 is more informative than 3CPro for describing molecular epidemiology and we hypothesize that accumulative mutations may have promoted the outbreak.

Etiology of Acute Conjunctivitis Due to Coxsackievirus A24 Variant, Human Adenovirus, Herpes Simplex Virus, and Chlamydia in Beijing, China

“…CA24v and EV70 were identified using a real-time one-step RT-PCR kit (Qiagen) using 2 pairs of previously described primers (20). Complete nucleotide sequences of VP1 genes of CA24v-positive specimens were amplified using a one-step RT-PCR kit (Qiagen) with specific primers as described previously (14,21). PCR products of 915 bp were purified and sequenced using an ABI PRISM310 Genetic Analyzer (Applied Biosystems, Foster City, CA, USA).…”

A major outbreak of conjunctivitis caused by coxsackievirus A24, Réunion, January to April 2015

“…CV-A24v belonging to genotype IV was identified in all the samples by sequencing of the VP1 coding region (Figure 4). The 10 VP1 partial nt sequences shared a 99.1 to 100% nt identity and had 95.1 to 97.9% nt similarity with sequences from genotype IV isolates previously identified in AHC outbreaks in Egypt (2010) [21], Japan (2011) [22], China (2007 and 2010) [23][24][25], Brazil (2009) [26], India (2007) and Singapore (2005) [27] (Figure 4). They also grouped in a larger cluster containing the VP1 sequence from a genotype IV isolate detected in a traveller returning from Comoros to France in 2012 (Figure 4; accession number JX196594).…”

Molecular epidemiology of acute hemorrhagic conjunctivitis caused by coxsackie A type 24 variant in China, 2004–2014

“…The major epidemic areas were in the east and south of China based on the national routine surveillance, and significantly higher numbers of cases were identified in Guangxi, Guangdong and Yunnan Provinces. Since 2010, several large epidemics of AHC outbreaks have occurred that were also reported in the south and east of China, including Guangdong, Yunnan, Jiangsu and Zhejiang Provinces131718192122, and the outbreaks were caused by CA24v13. In contrast, the west and the north of China were the areas with low epidemic rates.…”

“…The first outbreak of AHC in China was reported in Hong Kong in 1971, and a nationwide AHC epidemic caused by CA24v was reported in 20071316 with a total of 74,263 AHC cases. From 2007 to 2010, additional CA24v-associated AHC outbreaks were reported in Yunnan, Guangdong and Jiangsu Provinces as well as in Taiwan413171819. AHC could affect 50% of the population in communities within one or two months due to super human-to-human transmission71120.…”