Comparison of enterovirus 71 (E71) isolated from a patient with hand-foot-and-mouth disease in China to prototype E71 BrCr strain by polymerase chain reaction using a unique primer pair.

Hand-foot-and-mouth disease (HFMD) is a common disease seen in pediatric patients, that has been recognized in China since 1980. Coxsackievirus A16 (Cox A16) was identified initially as the causative agent of HFMD (Cao et al., 1985). In an epidemic that occurred in November, 1987, in Wuhan, Hubei Province, an enterovirus was isolated when fluid from a skin vesicle was cultured in primary human embryo lung cells. This was obtained from an adult patient with HFMD and designated isolate H. Subsequent serological identification showed that the H isolate could be neutralized by rabbit antiserum to E71 from Japan or China, as well as a monoclonal antibody (MoAb p27) to the E71 BrCr strain. This isolate could not be neutralized by WHO enterovirus LBM typing antiserum pools or other single typespecific antisera (Zheng et al., 1989). Recently, we have analyzed the 5'-non-coding region of the Cox A16 NIH strain, E71 BrCr strain and E71 H isolate by reverse transcriptase-directed polymerase chain reaction (RT-PCR) by using two pairs of primers (Table I). Since the 5'-non-coding region of approximately 740 nucleotides is highly conserved among the enteroviruses, the sequences of two primer pairs were used. However, we based our unique primer pair I on the Cox A9 nucleotide sequence (Chang et al., 1989) due to the lack of nucleotide sequence information for both E71 and Cox A16. Using primer pair II (Rotbart et al., 1990), we were able to detect a PCR product of 154 bp from Cox A16, E71 BrCr strain and the E71 H isolate. A PCR product of 397 bp was detected only from Cox A16 and E71 BrCr strain but not from the E71 H isolate using primer pair I (Fig. 1). In addition to HFMD, human E71 infection can produce central nerve system (CNS) disease similar to poliomyelitis. In Japan (Hagiwara et al., 1978), E71 causes