Co-administration of a plasmid encoding CD40 or CD63 enhances the immune responses to a DNA vaccine against bovine viral diarrhea virus in mice.

Bovine viral diarrhea virus (BVDV) causes substantial economic losses in the livestock industry worldwide. Plasmids encoding the BVDV E2 protein are potential DNA vaccines against BVDV, but their immunogenicity has been insufficient. Here, we investigated the adjuvant effect of CD40 and CD63 plasmids on the immune responses to a BVDV E2 DNA vaccine in mice. We constructed pUMVC4a-based plasmids encoding the BVDV E2 protein (pE2), mouse CD40 (pCD40), or mouse CD63 (pCD63). Protein expression by each plasmid was confirmed through Western blot analysis and immunofluorescence staining of cultured cell lines. BALB/c mice were immunized intradermally twice with pE2 in combination with, or without, pCD40 or pCD63, with 3 weeks between the two doses. pE2 with pCD40 induced significantly higher neutralizing antibody titers against BVDV than pE2 alone. pE2 with pCD63 induced significantly higher anti-E2 IgG2a antibody titers than pE2 alone. Furthermore, pE2 with pCD40 or pCD63 induced significantly increased lymphocyte proliferation and interferon (IFN)-γ production in response to BVDV, compared with E2 alone. These results suggest that a plasmid encoding CD40 or CD63 can be used as an adjuvant to enhance immune responses to DNA vaccines against BVDV.

Comparative Evaluation of Three Commercial Quantitative Real-Time PCRs Used in Japan for Bovine Leukemia Virus.

Bovine leukemia virus (BLV) is an oncogenic virus belonging to the genus Deltaretrovirus and is the causative agent of enzootic bovine leukosis. Proviral load (PVL) determined by real-time quantitative PCR (qPCR) is now widely used as an indicator of not only BLV infection, but also BLV disease progression. To interpret PVLs determined by different qPCRs used in Japan, we compared a chimeric cycling probe-based qPCR, CY415, targeting the BLV tax region; a TaqMan probe-based qPCR, RC202, targeting the BLV pol region; and a TaqMan probe-based qPCR, CoCoMo, targeting the BLV long terminal repeat (LTR) region. Whole-blood samples collected from 317 naturally BLV-infected cattle (165 Holstein-Friesian and 152 Japanese Black) and tumor tissue samples collected from 32 cattle at a meat inspection center were used. The PVLs determined by each qPCR were strongly correlated. However, the PVL and the proportion of BLV-infected cells determined by RC202 or CoCoMo were significantly higher than those determined by CY415. Genetic analysis of three tumor tissue samples revealed that LTR region mutations or a deletion affected the PVL determined by CoCoMo. These results suggest that the TaqMan-based RC202 or CoCoMo qPCR is better than CY415 for BLV PVL analysis. However, qPCR target region mutations were not rare in tumors and could hamper PVL analysis by using qPCR.