RESUMEN
Coxsackievirus A16 (CA16) is one of the major pathogens associated with human hand, foot, and mouth disease (HFMD) in the Asia-pacific region. Although CA16 infections are generally mild, severe neurological manifestations or even death has been reported. Studies on CA16 pathogenesis and vaccine development are severely hampered because the small animal models that are currently available show major limitations. In this study, gerbils (Meriones unguiculatus) were investigated for their suitability as an animal model to study CA16 pathogenesis and vaccine development. Our results showed that gerbils up to the age of 21 days were fully susceptible to CA16 and all died within five days post-infection. CA16 showed a tropism towards the skeletal muscle, spinal cord and brainstem of gerbils, and severe lesions, including necrosis, were observed. In addition, an inactivated CA16 whole-virus vaccine administrated to gerbils was able to provide full protection to the gerbils against lethal doses of CA16 strains. These results demonstrate that gerbils are a suitable animal model to study CA16 infection and vaccine development.
RESUMEN
OBJECTIVE: To analyze the epidemiological characteristics of hand foot and mouth disease (HFMD) in Ningbo. METHODS: A descriptive analysis was conducted through the surveillance data of HFMD in Ningbo, Zhejiang province, from 2008 to 2011. Genes on EV71 and Cox A16 were amplified with RT-PCT from the stool samples of HFMD patients. Sequences were analyzed by bioinformatics software. RESULTS: 37 524 cases of HFMD were reported from 2008 to 2011, including 196 severe cases and 12 deaths. The reported incidence was 145.26 per 100 000 and the case fatality was 0.03%. Cases in children aged 5 or younger accounted for 95.89%, and the scattered cases accounted for 64.10%. Xiangshan and Ninghai counties had the highest incidence rates in Ningbo. The peak of incidence was from April to July. The number of male patients was obviously higher than females. 2394 cases of HFMD were laboratory confirmed and EV71 with the predominant epidemic strain. Data from phylogenetic analysis revealed that EV71 isolated from HFMD patients in Ningbo belonged to C4a evolution branch of C4 sub-genotype, with several transmission chains. Cox A16 belonged to B1 evolution branch. 53.48% of the healthy children in Ningbo showed EV71 antibody positive. The geometric mean of the antibody titer (GMT) was 11.23 (8.33 - 14.98) in healthy children. Cox A16 antibody was detected at 63.18% of the healthy children in Ningbo. GMT in healthy children was 12.61 (6.70 - 16.52). CONCLUSION: HFMD was highly endemic in Ningbo, with children under 5 years old were at high-risk. The major etiologic agent was EV71 which belonged to C4a in the C4 sub-genotypes. Cox A16 belonged to the B1 evolution branch, which were in line with the predominant virus circulating in the mainland of China.