Rapid diagnosis of acute hemorrhagic conjunctivitis due to coxsackievirus A24 variant by real-time one-step RT-PCR

Molecular evolution of coxsackievirus A24v in Cuba over 23-years, 1986-2009

Coxsackievirus A24 variant (CVA24v) is a major causative agent of acute hemorrhagic conjunctivitis outbreaks worldwide, yet the evolutionary and transmission dynamics of the virus remain unclear. To address this, we analyzed and compared the 3C and partial VP1 gene regions of CVA24v isolates obtained from five outbreaks in Cuba between 1986 and 2009 and strains isolated worldwide. Here we show that Cuban strains were homologous to those isolated in Africa, the Americas and Asia during the same time period. Two genotypes of CVA24v (GIII and GIV) were repeatedly introduced into Cuba and they arose about two years before the epidemic was detected. The two genotypes co-evolved with a population size that is stable over time. However, nucleotide substitution rates peaked during pandemics with 4.39 × 10-3 and 5.80 × 10-3 substitutions per site per year for the 3C and VP1 region, respectively. The phylogeographic analysis identified 25 and 19 viral transmission routes based on 3C and VP1 regions, respectively. Pandemic viruses usually originated in Asia, and both China and Brazil were the major hub for the global dispersal of the virus. Together, these data provide novel insight into the epidemiological dynamics of this virus and possibly other pandemic viruses.

[Enteroviruses responsible for acute hemorrhagic conjunctivitis]

Acute hemorrhagic conjunctivitis (AHC) is an epidemic form of highly contagious conjunctivitis, characterized by conjunctival hemorrhages. The first AHC outbreak was described in 1969 in Ghana, West Africa, and was called Apollo disease, from the Apollo landing on the moon. This outbreak was caused by Enterovirus 70 (EV70) together with a Coxsackievirus A24 (CVA24v) variant, which are the major etiological agents involved in AHC outbreaks worldwide. AHC is known to be directly transmitted by close person-to-person contact or indirectly through soiled ophthalmological materials or unsafe recreational water. Recently, a possible airborne virus spread was suggested which could explain the high transmission rate of the disease. In the absence of a specific antiviral therapy, a rapid diagnosis of the causative agent is required to distinguish AHC due to enteroviruses from other ocular infectious diseases, for there are active drugs, or to quickly implement proper public health measures to limit the extension of the outbreak. However, virus identification remains difficult and time-consuming. Moreover, virological diagnosis is difficult to implement in developing countries where AHC has recently become a major problem for public health.

Molecular and immunocytochemical identification of coxsackievirus A-24 variant from the acute haemorrhagic conjunctivitis outbreak in Taiwan in 2007

AIMS

Acute haemorrhagic conjunctivitis (AHC) is a highly contagious conjunctivitis associated with enteroviruses. Coxsackie A-24 variant (CA-24v) and enterovirus-70 (EV-70) are the two major causative agents. During October 2007, an epidemic of AHC occurred in Taiwan, affecting more than 11 000 people. The aim of this study was to determine the aetiological agent associated with the outbreak in patients diagnosed with AHC and treated at the Cathay General Hospital, Taipei (CGHT) and Cathay General Hospital Sijhih (CGHS), Taiwan during October 2007.

METHODS

Virus isolates were obtained from six patients (four from CGHS and two from CGH), and a total of seven specimens (one throat and one rectal, and five eye swabs) were collected. The specimens were inoculated onto the MRC-5 cell lines. The viral isolation was confirmed by performing real-time reverse transcription-polymerase chain reaction (RT-PCR) and indirect immunofluorescence assay (IFA).

RESULTS

The conjunctival, throat, and rectal swabs collected in this study were all tested positive for a variant of CA-24. All seven viral isolates were characterized as a variant of CA-24 and confirmed by IFA and real-time RT-PCR.

CONCLUSIONS

The findings suggest that the outbreak of AHC that occurred during October 2007 in the northern area of Taiwan was caused by a variant of coxsackie A-24. Further phylogenic analysis is underway to further classify this CA-24v strain.

Molecular detection and characterization of human enteroviruses in Korean surface water

In this study, the genetic epidemiology of enteroviruses (EVs) in Korean surface water was evaluated by conducting phylogenetic analyses of the nucleotide sequences of the 5' non-coding region (5' NCR), which was determined by RT-PCR analysis of total culturable virus assay-positive samples. The results showed that the nucleotide sequences of the EVs could be classified into 4 genetic clusters, and that the predominant presence of Korea EVs were very similar to echoviruses type 30. Interestingly, two nucleotide sequences were very similar to those of coxsackievirus type B1 isolated from aseptic meningitis patients in Seoul, Korea, implying the possibility of a common source for the viruses circulated in water systems and humans. In addition, 3 nucleotide sequences clustered strongly with the nucleotide sequences from China or Japan, and one fell into the same cluster as echovirus type 11 from Taiwan, which suggests that EVs in Asia may have evolved in a region-specific manner. Taken together, the results of this study revealed that EVs from Korea surface waters could be genetically classified as coxsackieviruses or echoviruses, and that they evolved in Asia in a region-specific manner.