Expression, processing, and assembly of foot-and-mouth disease virus capsid structures in heterologous systems: induction of a neutralizing antibody response in guinea pigs

Abstract

Plasmids containing the foot-and-mouth disease virus structural protein precursor (P1) and 3C protease genes or the P1 gene alone were expressed in Escherichia coli. A recombinant baculovirus containing the P1 gene was also generated and expressed in Spodopterafrugiperda cells. Expression of the P1 and 3C genes in E. coli resulted in efficient synthesis and processing of the structural protein precursor and assembly into 70S empty capsids. This material reacted with neutralizing monoclonal antibodies which recognize only conformational epitopes and elicited a significant neutralizing antibody response in vaccinated guinea pigs. Expression of the P1 gene in E. coli resulted in synthesis of an insoluble product, whereas in insect cells infected with the recombinant baculovirus a soluble product was synthesized. Both soluble and insoluble P1 reacted with a 12S-specific monoclonal antibody, but only soluble P1 elicited a neutralizing antibody response in guinea pigs.

Distinctive features of foot-and-mouth disease virus, a member of the picornavirus family; aspects of virus protein synthesis, protein processing and structure

“…The initial experiments on PV using in vitro translation studies suggested that the lack of myristoylation inhibited proteolytic processing of the P1 precursor. However these results are at variance with more recent studies performed in cells with both PV and FMDV where apparently normal capsid protein processing is observed in the absence of this modification (Marc et al, 1990;Beisham et al, 1990Beisham et al, , 1991Lewis et al, 1991). PV RNA transfection experiments followed by sucrose gradient analyses showed that within a 12S fraction PV 1B was formed from the myristoylation negative RNA transcripts, indicating that lAB cleavage (concomitant with RNA packaging) had occurred (Marc et al, 1990).…”

“…Such direct studies have not been performed on other picornaviruses but some studies suggest that the results may differ in other systems. Indeed using FMDV cDNA Lewis et al (1991) expressed a P1-2A + 3C cassette (with an additional foreign four amino-acids fused to the amino-terminus of 1A) in E. coli and observed a low level of assembly into particles sedimenting at 70S (indicative of empty capsids). These particles contained 1C, 1D and a modified form of lAB.…”

Synthesis of empty capsid-like particles of Asia I foot-and-mouth disease virus in insect cells and their immunogenicity in guinea pigs

“…All of these results demonstrated that empty capsids of FMDV were similar to virions, and could be used to mimic virions immunologically. Several different expression systems have been used to produce empty capsid-like particles of FMDV (Lewis et al, 1991;Abrams et al, 1995;Mayr et al, 1999), however, many problems still exist such as poor immunogenic capability or low efficiency. Adenovirus based vaccine known for its best protective effects can protect 5 of 5 vaccinated cattle, but this vaccine is still unacceptable because of the limit for repeated vaccination and high cost.…”

Virus-like particle-based vaccines for animal viral infections

“…108 Probably, the poor results obtained with these and other FMDV-VLPs were due to their known low stability, which renders them notoriously difficult to obtain, usually with limited yields. 109,110 EMCV causes myocarditis in preweaned pigs and severe reproductive failure in sows 111,112 ; EMCV-VLPs were tested in the natural host, inoculated once or twice using an adjuvant. The immunization elicited neutralizing antibody levels similar to those obtained after administration of the commercial vaccine.…”