Dynamic change of mother-source neutralizing antibodies against enterovirus 71 and coxsackievirus A16 in infants.

BACKGROUND: Enterovirus 71 (EV71) and coxsackievirus A16 (Cox A16) are major causative agents for hand, foot and mouth disease (HFMD). Studies indicate that the frequent HFMD outbreaks result in a few hundreds children's death in China in recent years. The vaccine and other research for HFMD need to be developed urgently.

THE AIMS OF OUR STUDY WERE: to explore dynamic development of mother-source neutralizing antibodies against EV71 and Cox A16 in infants from Jiangsu Province, China, and to provide the fundamental data for further establishing of corresponding immunization course.

METHODS: Peripheral blood samples were collected from 133 of parturient women once immediately before delivery and their infants at two and seven months of age. Method of micro-dose cytopathogenic effect was used to measure neutralizing antibodies against EV71 and Cox A16, respectively.

RESULTS: Seropositive rates of anti-EV71 and anti-Cox A16 in prenatal women were 79.7% (106/133) and 92.5% (123/133), respectively; geometric mean titers (GMTs) were 29.0 and 61.9; 75.9% (101/133) prenatal women were both positive in anti-EV71 and anti-Cox A16; seropositive rates of anti-EV71 and anti-Cox A16 were 25.6% (34/133) and 38.3% (51/133) in infants at two months of age; GMTs were 12.3 and 18.0, respectively. GMTs of anti-EV71 were significantly higher for infants at seven months (82.6) compared with that at two months (P < 0.05), showing infants had inapparently infected by EV71 during two to seven months. Although only one offspring (0.75%) at seven months was found having anti-Cox A16 transfered from maternal, this observation suggested no maternal antibody may remain in infants at seven months.

CONCLUSIONS: The prevalence of EV71 and Cox A16 were relatively high in Jiangsu Province. Bivalent vaccine against both EV71 and Cox A16 should be developed, and the ideal time point for prime immunization for infants is around 2-5 months of age.