PRRS is the most costly disease U.S. swine producers confront and little progress has been made in recent years to improve the situation. Prevention and control of PRRS has been difficult, in part because our knowledge of the immunity against PRRSV is limited. We know that antibodies generated during the early phase of infection cannot neutralize the virus; neutralizing antibodies and cellular immune responses appear much later in the course of infection; and animals remain persistently infected despite an active immune response.
In studying swine antibody responses, this laboratory has discovered the presence of serum auto-anti-idiotypic antibodies in pigs experimentally infected with PRRSV. These auto-anti-idiotypic antibodies are specific for anti-GP5 and anti-M antibodies. One set of the auto-anti-idiotypic antibodies mimics GP5 antigen, identifies a putative virus receptor on swine macrophages. Both in vitro and in vivo studies showed that this auto-anti-idiotypic antibody blocked PRRSV infection. The anti-idiotype technique represents a new approach representing a major advance for further understanding the pigs’ immunological response to PRRSV infection and providing a new tool to bring a potential alternative anti-idiotype vaccine to the field.
