Optimization in the expression of ASFV proteins for the development of subunit vaccines using poxviruses as delivery vectors

Abstract

African swine fever virus (ASFV) causes a highly contagious hemorrhagic disease that affects domestic pig and Eurasian wild boar populations. To date, no safe and efficacious treatment or vaccine against ASF is available. Nevertheless, there are several reports of protection elicited by experimental vaccines based on live attenuated ASFV and some levels of protection and reduced viremia in other approaches such as DNA, adenovirus, baculovirus, and vaccinia-based vaccines. Current ASF subunit vaccine research focuses mainly on delivering protective antigens and antigen discovery within the ASFV genome. However, due to the complex nature of ASFV, expression vectors need to be optimized to improve their immunogenicity. Therefore, in the present study, we constructed several recombinant MVA vectors to evaluate the efficiency of different promoters and secretory signal sequences in the expression and immunogenicity of the p30 protein from ASFV. Overall, the natural poxvirus PrMVA13.5L promoter induced high levels of both p30 mRNA and specific anti-p30 antibodies in mice. In contrast, the synthetic PrS5E promoter and the S E/L promoter linked to a secretory signal showed lower mRNA levels and antibodies. These findings indicate that promoter selection may be as crucial as the antigen used to develop ASFV subunit vaccines using MVA as the delivery vector.

Orally administered recombinant Lactobacillus expressing African swine fever virus antigens that induced immunity responses

“…To date, reliable animal models and biosafety level-3 (BSL-3) laboratories have made it challenging to evaluate the immunological effects of vaccines in vivo . A number of recent studies, including those by Lopera-Madrid ( Lopera-Madrid et al, 2021 ), Sugisawa ( Sugisawa et al, 2022 ), Wang ( Wang et al, 2022 ), et al, have used mice as a model to assess ASF experiences. Importantly, promising results by Barasona et al (2019) provided hope for the design of oral ASFV vaccines.…”

Vaccines for African swine fever: an update

“…ASF subunit vaccine, which primarily delivers protective antigens and antigen discovery within the ASFV genome, has recently emerged as a promising strategy against ASF ( Lopera-Madrid et al, 2021 ). The ASFV subunit vaccine, as previously mentioned, is a potential vaccine that can effectively produce specific humoral and cellular immunity after specific gene and protein expression.…”

“…Notably, Mazloum et al accelerated the understanding of the effect of proteins with unknown functions on ASF virus replication in the CV-1 cell line by evaluating recombinant plasmids pCI-neo/E248R, pCI-neo/EP402R, and pCI-neo/X69R ( Mazloum et al, 2019 ). Thus, Several recombinant MVA vectors were constructed by Lopera-Madrid et al (2021) to evaluate the efficiency of different promoters and secretion signal sequences on ASFV p30 protein expression and immunogenicity. These results indicate that promoter selection may be as vital as the antigen used to develop ASFV subunit vaccines.…”

Lactobacillus plantarum Surface-Displayed ASFV (p14.5) Can Stimulate Immune Responses in Mice

“…To date, no safe and efficacious treatment or vaccine against ASF is available. Nevertheless, there are several reports of protection elicited by experimental vaccines based on the subunit vaccine ASFV [ 3 ]. The entire genome of ASFV contains 167 open reading frames (ORFs), which can encode from 150–200 proteins and approximately 50 of them are structural proteins [ 4 ], including the p14.5 protein.…”