Antigenic and immunogenic properties of a chimera of two immunodominant African swine fever virus proteins

Abstract

A chimera of the two immunodominant African swine fever (ASF) virus proteins p54 and p30 was constructed by insertion of the gene CP204L into a Not I restriction site of E183L gene. The resulting chimeric protein p54/30, expressed by a recombinant baculovirus in insect cells and in Trichoplusia ni larvae, retained antigenic determinants present in both proteins and reacted in Western blot with a collection of sera from inapparent ASF virus carrier pigs. Remarkably, pigs immunized with the chimeric protein developed neutralizing antibodies and survived the challenge with a virulent African swine fever virus, presenting a reduction of about two logs in maximum viremia titers with respect to control pigs. In conclusion, this study revealed that the constructed chimeric protein may have utility as a serological diagnostic reagent and for further immunological studies that may provide new insights on mechanisms of protective immunity to ASFV.

Induction of Robust Immune Responses in Swine by Using a Cocktail of Adenovirus-Vectored African Swine Fever Virus Antigens

“…In addition, ASFV-specific CTL activity is detected in swine infected with nonlethal ASFV isolates (9,10,12,13). The requirement for CTLs in protection is further supported by the observation that adjuvant-formulated killed ASFV and recombinant vaccine candidate antigens that induce high antibody responses do not confer solid protection, and these outcomes strongly suggest that major histocompatibility complex (MHC) class I presentation of ASFV antigens is critical (15,(22)(23)(24)(25). In addition, it has been observed that swine that generate high antibody titers but low cellular responses following immunization with a live attenuated virus develop chronic disease (26).…”

“…Subunit vaccines based on some of the most extensively studied ASFV antigens, such as p32, p54, and p72 envelope protein, have shown some promise. These antigens, among others, have been tested as vaccine candidates either as baculovirus-expressed recombinant proteins or via DNA plasmid delivery (15,(22)(23)(24)(25). Delayed onset of viremia, delayed mortality, and partial protection have been observed in most of these studies, which suggest that these antigens do play a role in protection but are not capable of conferring complete protection when they are used singly or in combination.…”

Expression Library Immunization Can Confer Protection against Lethal Challenge with African Swine Fever Virus

“…Different attempts to develop an efficient and safe vaccine against ASF have been made, so far with not very consistent results. Thus, immunization with baculovirus-expressed recombinant p54 and p30 ASFV proteins (13,14), with the viral hemagglutinin (15), or with a combination of p54, p30, p72, and p22 (16) has yielded different protective outcomes, also depending on the ASFV strain used for the challenge. These studies have, more recently, been extended to the field of immunization with DNA (17,18).…”

Phenotype-Based Identification of Host Genes Required for Replication of African Swine Fever Virus

“…Expression of ASFV early and late genes in BAT3 EST sense and antisense clones. Production of the ASFV early and late proteins p30 and p72, respectively (7,11,23,70) was assayed by fluorescence microscopy following ASFV infection of HeLatTA cells containing the BAT3 1.3-3s or BAT3 1.3-4as constructs. At different times after infection, cells were fixed and the presence of these early or late proteins was determined using fluorescein-labeled antibodies generated against the ASFV p30 or p72 proteins.…”