Protective Efficacies of Formaldehyde-Inactivated Whole-Virus Vaccine and Antivirals in a Murine Model of Coxsackievirus A10 Infection

Abstract

Coxsackievirus A10 (CVA10) is one of the major pathogens associated with hand, foot, and mouth disease (HFMD). CVA10 infection can cause herpangina and viral pneumonia, which can be complicated by severe neurological sequelae. The morbidity and mortality of CVA10-associated HFMD have been increasing in recent years, particularly in the pan-Pacific region. There are limited studies, however, on the pathogenesis and immunology of CVA10-associated HFMD infections, and few antiviral drugs or vaccines have been reported. In the present study, a cell-adapted CVA10 strain was employed to inoculate intramuscularly 5-day-old ICR mice, which developed significant clinical signs, including reduced mobility, lower weight gain, and quadriplegia, with significant pathology in the brain, hind limb skeletal muscles, and lungs of infected mice in the moribund state. The severity of illness was associated with abnormally high expression of the proinflammatory cytokine interleukin 6 (IL-6). Antiviral assays demonstrated that ribavirin and gamma interferon administration could significantly inhibit CVA10 replication both and In addition, formaldehyde-inactivated CVA10 whole-virus vaccines induced immune responses in adult mice, and maternal neutralizing antibodies could be transmitted to neonatal mice, providing protection against CVA10 clinical strains. Furthermore, high-titer antisera were effective against CVA10 and could relieve early clinical symptoms and improve the survival rates of CVA10-challenged neonatal mice. In summary, we present a novel murine model to study CVA10 pathology that will be extremely useful in developing effective antivirals and vaccines to diminish the burden of HFMD-associated disease. Hand, foot, and mouth disease cases in infancy, arising from coxsackievirus A10 (CVA10) infections, are typically benign, resolving without any significant adverse events. Severe disease and fatalities, however, can occur in some children, necessitating the development of vaccines and antiviral therapies. The present study has established a newborn-mouse model of CVA10 that, importantly, recapitulates many aspects of human disease with respect to the neuropathology and skeletal muscle pathology. We found that high levels of the proinflammatory cytokine interleukin 6 correlated with disease severity and that ribavirin and gamma interferon could decrease viral titers and Whole-virus vaccines produced immune responses in adult mice, and immunized mothers conferred protection on neonates against challenge from CVA10 clinical strains. Passive immunization with high-titer antisera could also improve survival rates in newborn animals.

柯萨奇病毒b4诱导急性心肌炎和大脑皮层神经元水肿小鼠模型的建立

“…Clinical studies have shown that the high expressions of several cytokines, such as IL-6, TNF-α, and IL-10, are closely correlated with clinical manifestations and complications associated with CV-B4 infection ( Alidjinou et al, 2013 ; Gu et al, 2009 ). Our data showed that after neonatal mice were inoculated with CV-B4, there was a gradual increase in the level of IL-6 in serum, different from that observed in enterovirus species A virus infection (CV-A6 and CV-A10) in ICR neonatal mice ( Zhang et al, 2017a , b ). Our previous studies on CV-A6 and CV-A10 mouse models of infection also showed high expression levels of IL-6 throughout all stages of infection ( Zhang et al, 2017a , b ).…”

“…Our data showed that after neonatal mice were inoculated with CV-B4, there was a gradual increase in the level of IL-6 in serum, different from that observed in enterovirus species A virus infection (CV-A6 and CV-A10) in ICR neonatal mice ( Zhang et al, 2017a , b ). Our previous studies on CV-A6 and CV-A10 mouse models of infection also showed high expression levels of IL-6 throughout all stages of infection ( Zhang et al, 2017a , b ). Therefore, we speculate that the differences in pathogenicity between CV-A and CV-B enteroviral species in the same neonatal ICR murine model may be attributable to differences in skeletal muscle tropisms and proinflammatory cytokine expression levels, such as that of IL-6, in peripheral blood.…”

“…Previous in vivo experiments studying EV-A71 infection have shown that treatment with anti-IL-6 neutralizing antibodies increases survival rates, whereas treatment with IL-6 can exacerbate pulmonary dysfunction in EV-A71-infected mice ( Khong et al, 2011 ). We also observed this latter phenomenon of disease exacerbation in CV-A6 and CV-A10 murine models of infection ( Zhang et al, 2017a , b ).…”

“…In addition, readily discernible pathological changes were detected in both brain and myocardial tissue. Compared with enterovirus species A virus infection models, including EV-A71 ( Dong et al, 2016 ; Yue et al, 2016 ), CV-A16 ( Huang et al, 2015 ; Mao et al, 2012 ), CV-A6 ( Zhang et al, 2017b ), and CV-A10 ( Zhang et al, 2017a ), which are associated with hind limb paralysis and/or severe respiratory involvement, the enterovirus species B CV-B4 had comparably minor pathology in skeletal muscle and lung tissue.…”

“…Real-time PCR thermocycling was performed on a LightCycler 96 platform with the following conditions: 95 °C for 10 min; 40 cycles of 95 °C for 15 s, and 60 °C for 1 min. Standard curves for absolute quantification of CV-B4 copy numbers in different tissue and blood samples were established, as described previously ( Zhang et al, 2017a , b ).…”