[Detection of enterovirus 70 in acute hemorrhagic conjunctivitis by PCR-stringent microplate hybridization method]

The surveillance of acute hemorrhagic conjunctivitis (AHC) caused by enterovirus 70 (EV70) is insufficient because of the difficulties of virus isolation using conventional methods. In this study, reverse transcription-polymerase chain reaction (RT-PCR) and stringent microplate hybridization (SMH) methods were assessed for the detection of EV70 in conjunctival swabs collected from the patients of AHC which broke out in Miyazaki Prefecture in 1990 and Okinawa Prefecture in 1994. Furthermore, with the use of the SMH method, we compared the genetic homogeneity of EV70 detected from the samples collected in 1990 and 1994 to the J670/71 strain isolated approximately 25 years ago. A similar investigation was performed between recent coxsackievirus A24 variant (CA24v) and EH24/70 strain, a standard strain of CA24v that was isolated approximately 25 years ago. As a result, RT-PCR products were detected in 26 of 34 conjunctival swabs collected in Miyazaki Prefecture in 1990. Likewise, RT-PCR products were detected in 9 of 10 conjunctival swabs collected in Okinawa Prefecture in 1994, and these RT-PCR products were all identified as EV70 by SMH method. Such a high level of virus recovery from specimen shows the evidence of usefulness of these techniques. Recent EV70 showed a reaction of about 60% to a probe synthesized with J670/71. Likewise, recent CA24v showed a reaction of about 30% to a probe synthesized with EH24/70. These finding are highly suggestive of the progress of viral mutation.