t can efficiently mature and activate DCs to deliver heterologous antigens through non-classical cross-priming pathways, generating antigen-specific T-cells. Yeast expressing viral antigens can be degraded in proteasomes and endosomes, presented through MHC class I and MHC class II, leading to the recruitment and activation of antigen-specific CD4^+^ and CD8^+^ T cells. CD4^+^ T cells release immunostimulatory T~H~-1 type inflammatory cytokines, such as interleukin-2 (IL-2) and interferon-γ (IFN-γ), which further induce the activation and proliferation of CD8^+^ T cells \[[@B3],[@B30]\]. Second, the dose of yeast applied and immunization route can also lead to weak neutralization. In our study, subcutaneous immunization with 2 × 10^8^ Yeast-GP5 primarily induced T cell responses, while oral immunization with 5 × 10^8^ Yeast-GP5 induced higher levels of intestinal mucosal sIgA and IFN-γ secretion. However, PRRSV-specific IgG induced by Yeast-GP5 in serum was relatively weak, regardless of the immunization routes we used here. A previous study showed that intramuscular injection of recombinant *Hansenula polymorpha* expressing hepatitis B virus surface antigen (yeast-HBsAg) induced both humoral and cellular immune responses in mice \[[@B7]\]. However, the production of HBsAg-specific IgG antibody was related to the number of yeast-HBsAg used for vaccination. When the number of yeast used was lower, almost no HBsAg-specific IgG antibodies were detected. The differences in the routes of immunization, expression levels of antigen in the yeast cells and numbers of applied yeast cells may account for the different results. In addition, since yeasts are eukaryotic, they are capable of modifying recombinant proteins according to a general eukaryotic scheme. However, several studies have shown that glycosylation of antigen played an important role in avoiding or minimizing virus-neutralizing Ab response *via* a N-glycan-shielding mechanism \[[@B11],[@B36]\]. Inoculation of pigs with mutant viruses carrying mutations a