[Rhabdoviruses]

Application and development of a TaqMan-based real-time PCR assay for rapid detection of snakehead vesiculovirus

Snakehead vesiculovirus (SHVV) is one of the primary pathogens responsible for viral diseases in the snakehead fish. A TaqMan-based real-time PCR assay was established for the rapid detection and quantification of SHVV in this study. Specific primers and fluorescent probes were designed for phosphoprotein (P) gene, and after optimizing the reaction conditions, the results indicated that the detection limit of this method could reach 37.1 copies, representing a 100-fold increase in detection sensitivity compared to RT-PCR. The specificity testing results revealed that this method exhibited no cross-reactivity with ISKNV, LMBV, RSIV, RGNNV, GCRV, and CyHV-2. Repetition experiments demonstrated that both intra-batch and inter-batch coefficients of variation were not higher than 1.66%. Through in vitro infection experiments monitoring the quantitative changes of SHVV in different tissues, the results indicated that the liver and spleen exhibited the highest viral load at 3 poi. The TaqMan-based real-time PCR method established in this study exhibits high sensitivity, excellent specificity, and strong reproducibility. It can be employed for rapid detection and viral load monitoring of SHVV, thus providing a robust tool for the clinical diagnosis and pathogen research of SHVV.

Viral suppression function of intracellular antibody against C-terminal domain of rabies virus phosphoprotein

Rabies virus (RV) causes a fatal disease in both human and animals. The disease can be prevented by post-exposure prophylaxis in individuals exposed to RV. However, the neutralization effect is limited after the virus enters into the host cells. So, it is important to identify new targets for rabies therapy. In this study, a human antibody RV1A2 specific to RV phosphoprotein (RV-P) was generated from a human naïve immune antibody library. The antibody recognized all forms of the phosphoproteins including the full length (P1) and short length of the P proteins (P2, P3, P4, and P5). The epitope mapping and the molecular docking of antigen-antibody complex showed that the antibody targets at a conserved epitope of 'VLGWV' ranging from amino acid (aa) 262 to 266 at C-terminal domain of the P protein, which locates at a hydrophobic pocket region in the C-terminal of the RV-P. The aa W265 within the epitope is on the flat surface of the domain, suggesting that it may be a critical amino acid for the functions of the P protein. Our results further showed that intracellular antibody RV1A2 which targets at the C-terminal domain of the P protein could effectively inhibit RV propagation 2-4 days post infection. These results suggest that the conserved C-terminal domain may be used as a new target for drug discovery, which highlights an intracellular inhibition of RV propagation and provides a potential novel way to treat RV infection.