Expression, purification and immunodetection of a recombinant fragment (residues 179–281) of the G protein from rabies virus ERA strain

Construction and evaluation of recombinant Lactobacillus plantarum NC8 delivering one single or two copies of G protein fused with a DC-targeting peptide (DCpep) as novel oral rabies vaccine

Rabies remains an important public health threat in most developing countries. To develop a more effective and safe oral vaccine against rabies, we constructed recombinant Lactobacillus plantarum NC8 carrying one or two copies of the G gene with a dendritic cell-targeting peptide (DCpep) fused at the C-terminal designated NC8-pSIP409-sRVG or NC8-pSIP409-dRVG, respectively. The immunogenicity and protective efficacy of these recombinant Lactobacillus plantarum against RABV were evaluated by oral administration in a mouse model. The results showed that recombinant NC8-pSIP409-dRVG possessed more G protein, resulting in more functional maturation of DCs. After three cycle of oral immunization, NC8-pSIP409-dRVG induced significantly higher levels of specific IgG antibody and mixed Th1/Th2 with a strong Th1-biasd immune response in mice. Most importantly, although the titers of RABV neutralizing antibody (VNA) were below the threshold of 0.5 IU/mL, the NC8-pSIP409-dRVG could protect 60 % of inoculated mice against lethal RABV challenge. These data reveal that recombinant NC8-pSIP409-dRVG may be a novel and promising oral vaccine candidate to prevent and control of animal rabies.

The chaperonin CCTα is required for efficient transcription and replication of rabies virus

Negri bodies (NBs) are formed in the cytoplasm of rabies virus (RABV)-infected cells and are accompanied by a number of host factors to NBs, in which replication and transcription occur. Here, it was found that chaperonin containing TCP-1 subunit alpha (CCTα) relocalizes to NBs in RABV-infected cells, and that cotransfection of nucleo- and phospho-proteins of RABV is sufficient to recruit CCTα to the NBs' structure. Inhibition of CCTα expression by specific short hairpin RNA knockdown inhibited the replication and transcription of RABV. Therefore, this study showed that the host factor CCTα is associated with RABV infection and is very likely required for efficient virus transcription and replication.

Novel monoclonal antibodies that bind to wild and fixed rabies virus strains

Ten monoclonal antibodies (MAbs) against rabies virus, including IgG3κ, IgG2aκ, IgMκ, and an IgG2bκ isotype, were produced and characterized using neutralization, ELISA, immunodot-blot, and immunofluorescence assays. MAb 8D11, which recognized rabies virus glycoprotein, was found to neutralize rabies virus in vitro. When submitted to an immunofluorescence assay, seven MAbs showed different reactivity against 35 Brazilian rabies virus isolates. Three MAbs (LIA 02, 3E6, and 9C7) only failed to recognize one or two virus isolates, whereas MAb 6H8 was found to be reactive against all virus isolates tested. MAbs were also evaluated for their immunoreactivity against fixed rabies virus strains present in human and veterinary commercial vaccines. MAbs LIA 02, 6H8, and 9C7 reacted against all vaccine strains, while the remaining MAbs recognized at least 76% of vaccine strains tested. This research provides a set of MAbs with potential application for improving existing or developing new diagnostic tests and immunoassays.

Recombinant protein-based viral disease diagnostics in veterinary medicine

Identification of pathogens or antibody response to pathogens in human and animals modulates the treatment strategies for naive population and subsequent infections. Diseases can be controlled and even eradicated based on the epidemiology and effective prophylaxis, which often depends on development of efficient diagnostics. In addition, combating newly emerging diseases in human as well as animal healthcare is challenging and is dependent on developing safe and efficient diagnostics. Detection of antibodies directed against specific antigens has been the method of choice for documenting prior infection. Other than zoonosis, development of inexpensive vaccines and diagnostics is a unique problem in animal healthcare. The advent of recombinant DNA technology and its application in the biotechnology industry has revolutionized animal healthcare. The use of recombinant DNA technology in animal disease diagnosis has improved the rapidity, specificity and sensitivity of various diagnostic assays. This is because of the absence of host cellular proteins in the recombinant derived antigen preparations that dramatically decrease the rate of false-positive reactions. Various recombinant products are used for disease diagnosis in veterinary medicine and this article discusses recombinant-based viral disease diagnostics currently used for detection of pathogens in livestock and poultry.