Rapid and efficient construction of recombinant bovine herpesvirus 1 genomes

Utilization of herpesviridae as recombinant viral vectors in vaccine development against animal pathogens

Throughout the past few decades, numerous viral species have been generated as vaccine vectors. Every viral vector has its own distinct characteristics. For example, the family herpesviridae encompasses several viruses that have medical and veterinary importance. Attenuated herpesviruses are developed as vectors to convey heterologous immunogens targeting several serious and crucial pathogens. Some of these vectors have already been licensed for use in the veterinary field. One of their prominent features is their capability to accommodate large amount of foreign DNA, and to stimulate both cell-mediated and humoral immune responses. A better understanding of vector-host interaction builds up a robust foundation for the future development of herpesviruses-based vectors. At the time, many molecular tools are applied to enable the generation of herpesvirus-based recombinant vaccine vectors such as BAC technology, homologous and two-step en passant mutagenesis, codon optimization, and the CRISPR/Cas9 system. This review article highlights the most important techniques applied in constructing recombinant herpesviruses vectors, advantages and disadvantages of each recombinant herpesvirus vector, and the most recent research regarding their use to control major animal diseases.

Selection and characterization of canine, swine and rabbit cell lines resistant to bovine viral diarrhea virus

Contamination of cell cultures with adventitious viruses may pose serious risks for virology diagnosis, research and vaccine production. This article reports the selection and characterization of three cell lines resistant to bovine viral diarrhea virus (BVDV), a major contaminant of cell cultures. The resistant cells were obtained from canine (MDCK), swine (PK-15) and rabbit (RK-13) parental cell lines by expanding and cloning cells that survived lytic infection with BVDV. All three selected cell lines were resistant to three standard BVDV strains and to 10 field isolates as demonstrated by immunofluorescence for viral antigens and by co-cultivation with susceptible cells. Inoculation of selected cells with BVDV (10 TCID50/cell) resulted in frequencies of infection of <10(-5) (MDCK-R, PK-15R) and 3.3 x 10(-4) (RK-13R). Comparing to the parental cell lines, these cells were >10,000-, >20,000- and 600-fold less susceptible to BVDV, respectively. Inoculation of resistant cells with BVDV in the presence of polyethylene-glycol increased the frequency of infection in the order of >437-, >346- and 87-fold, respectively, indicating that resistance is probably due to a block in viral entry. Nevertheless, each resistant cell line retained the susceptibility to three other viruses that replicate in the parental cells. Thus, these cells may be useful for many virology purposes, with a very low risk of BVDV contamination.