Immunogenicity of the capsid precursor and a nine-amino-acid site-directed mutant of the 3C protease of foot-and-mouth disease virus coexpressed by a recombinant goatpox virus

VP0 Myristoylation Is Essential for Senecavirus A Replication

Many picornaviruses require the myristoylation of capsid proteins for viral replication. Myristoylation is a site-specific lipidation to the N-terminal G residue of viral proteins, which is catalyzed by the ubiquitous eukaryotic enzyme N-myristoyltransferase (NMT) by allocating the myristoyl group to the N-terminal G residue. IMP-1088 and DDD85646 are two inhibitors that can deprive NMT biological functions. Whether Senecavirus A (SVA) uses NMT to modify VP0 and regulate viral replication remains unclear. Here, we found that NMT inhibitors could inhibit SVA replication. NMT1 knock-out in BHK-21 cells significantly suppressed viral replication. In contrast, the overexpression of NMT1 in BHK-21 cells benefited viral replication. These results indicated that VP0 is a potential NMT1 substrate. Moreover, we found that the myristoylation of SVA VP0 was correlated to the subcellular distribution of this protein in the cytoplasm. Further, we evaluated which residues at the N-terminus of VP0 are essential for viral replication. The substitution of N-terminal G residue, the myristoylation site of VP0, produced a nonviable virus. The T residue at the fifth position of the substrates facilitates the binding of the substrates to NMT. And our results showed that the T residue at the fifth position of VP0 played a positive role in SVA replication. Taken together, we demonstrated that SVA VP0 myristoylation plays an essential role in SVA replication.

Effect of Foot-and-Mouth Disease Virus 2B Viroporin on Expression and Extraction of Mammalian Cell Culture Produced Foot-and-Mouth Disease Virus-like Particles

To improve the production of foot-and-mouth disease (FMD) molecular vaccines, we sought to understand the effects of the FMD virus (FMDV) 2B viroporin in an experimental, plasmid-based, virus-like particle (VLP) vaccine. Inclusion of the FMDV viroporin 2B into the human Adenovirus 5 vectored FMD vaccine enhanced transgene expression despite independent 2B expression negatively affecting cell viability. Evaluating both wildtype 2B and mutants with disrupted viroporin activity, we confirmed that viroporin activity is detrimental to overall transgene expression when expressed independently. However, the incorporation of 2B into an FMD molecular vaccine construct containing a wildtype FMDV 3C protease, a viral encoded protease responsible for processing structural proteins, resulted in enhancement of transgene expression, validating previous observations. This benefit to transgene expression was negated when using the FMDV 3C^L127P mutant, which has reduced processing of host cellular proteins, a reversion resulting from 2B viroporin activity. Inclusion of 2B into VLP production constructs also adversely impacted antigen extraction, a possible side effect of 2B-dependent rearrangement of cellular membranes. These results demonstrate that inclusion of 2B enhanced transgene expression when a wildtype 3C protease is present but was detrimental to transgene expression with the 3C^L127P mutant. This has implications for future molecular FMD vaccine constructs, which may utilize mutant FMDV 3C proteases.

Capripoxvirus Infections in Ruminants: A Review

Lumpy skin disease, sheeppox, and goatpox are notifiable diseases of cattle, sheep, and goats, respectively, caused by viruses of the Capripoxvirus genus. They are responsible for both direct and indirect financial losses. These losses arise through animal mortality, morbidity cost of vaccinations, and constraints to animals and animal products' trade. Control and eradication of capripoxviruses depend on early detection of outbreaks, vector control, strict animal movement, and vaccination which remains the most effective means of control. To date, live attenuated vaccines are widely used; however, conferred protection remains controversial. Many vaccines have been associated with adverse reactions and incomplete protection in sheep, goats, and cattle. Many combination- and recombinant-based vaccines have also been developed. Here, we review capripoxvirus infections and the immunity conferred against capripoxviruses by their respective vaccines for each ruminant species. We also review their related cross protection to heterologous infections.

Construction of recombinant capripoxviruses as vaccine vectors for delivering foreign antigens: Methodology and application

Goatpox (GTP), sheeppox (SPP) and lumpy skin disease (LSD) are three severe diseases of goat, sheep and cattle. Their typical clinical symptoms are characterized by vesicles, papules, nodules, pustules and scabs on animal skins. The GTP, SPP and LSD are caused by goatpox virus (GTPV), sheeppox virus (SPPV) and lumpy skin disease virus (LSDV), respectively, all of which belong to the genus Capripoxvirus in the family Poxviridae. Several capripoxvirus (CaPV) isolates have been virulently attenuated through serial passaging in vitro for production of live vaccines. CaPV-based vector systems have been broadly used to construct recombinant vaccines for delivering foreign antigens, many of which have been demonstrated to induce effective immune protections. Homologous recombination is the most commonly used method for constructing recombinant CaPVs. Here, we described a methodology for generation of recombinant CaPVs by the homologous recombination, and further reviewed CaPV-vectored vaccines for delivering foreign antigens.

Tomorrow's vector vaccines for small ruminants

Inactivated and attenuated vaccines have contributed to the control or even the eradication of significant animal pathogens. However, these traditional vaccine technologies have limitations and disadvantages. Inactivated vaccines lack efficacy against certain pathogens, while attenuated vaccines are not always as safe. New technology vaccines, namely DNA and recombinant viral vector vaccines, are being developed and tested against pathogens of small ruminants. These vaccines induce both humoral and cellular immune responses, are safe to manufacture and use and can be utilized in strategies for differentiation of infected from vaccinated animals. Although there are more strict regulatory requirements for the safety standards of these vaccines, once a vaccine platform is evaluated and established, effective vaccines can be rapidly produced and deployed in the field to prevent spread of emerging pathogens. The present article offers an introduction to these next generation technologies and examples of vaccines that have been tested against important diseases of sheep and goats.