Prevalent human coxsackie B-5 virus infects porcine islet cells primarily using the coxsackie-adenovirus receptor.

Abstract

We have previously demonstrated that transplanting porcine encephalomyocarditis virus (EMCV)-infected porcine islet cells (PICs) results in transmission of the virus to recipient mice, which is manifested by acute fatal infection within 5 to 8 days. Here, we determined PIC susceptibility to a related and highly prevalent human picornavirus, coxsackie B-5 virus (CVB-5). PICs were inoculated with CVB-5 in vitro for up to 96 hours and infectivity, level of virus replication, and cellular function determined. Subsequently, monoclonal and polyclonal antibody blocking experiments were used to investigate the receptor CVB-5 uses to enter PICs, and the ability of CVB-5-infected islets to reverse diabetes analyzed in mice. Adult pig islets inoculated with CVB-5 in vitro showed a typical picornaviral replication cycle with a 2-h lag phase followed by a 4-h exponential phase during which the virus titer increased by 4 logs. However, CVB-5 was less cytolytic to PICs than EMCV, resulting in a persistent productive infection lasting for up to 96 h, with minimal evidence of cell lysis. Double immunostaining confirmed the presence of CVB-5 antigens in insulin-producing islets. Infection of PICs in the presence of antibodies against human coxsackie-adenovirus receptor (CAR) resulted in near complete blockage in production of infectious virus particles whereas blocking with anti-porcine decay-accelerating factor (DAF, also called CD55) or anti-porcine membrane cofactor protein (MCP, also called CD46) only slightly decreased the number of infectious CVB-5 particles produced. Immunofluoresence staining showed CAR and MCP expression on the islet surface, but not DAF. Transplanting CVB-5-infected PICs into diabetic C57BL/6 mice resulted in reversal of diabetes. Although PICs are susceptible to human CVB-5, the infection does not appear to affect xenograft function in vitro or in vivo in the short term.