Oral Vaccination of Recombinant Saccharomyces cerevisiae Expressing ORF132 Induces Protective Immunity against Cyprinid Herpesvirus-2

Cyprinid herpesvirus 2 (CyHV-2) is the etiological agent of herpesviral hematopoietic necrosis (HVHN) disease, which causes serious economic losses in the crucian carp culture industry. In this study, by displaying ORF132 on the surface of Saccharomyces cerevisiae cells (named EBY100/pYD1-ORF132), we evaluated the protective efficacy of oral administration against CyHV-2 infection. Intense innate and adaptive immune responses were evoked in both mucosal and systemic tissues after oral vaccination with EBY100/pYD1-ORF132. Importantly, oral vaccination provided significant protection for crucian carp post CyHV-2 infection, resulting in a relative percent survival (RPS) of 64%. In addition, oral administration suppressed the virus load and relieved histological damage in selected tissues. Our results indicated that surface-displayed ORF132 on S. cerevisiae could be used as potential oral vaccine against CyHV-2 infection.