Production of mink enteritis parvovirus empty capsids by expression in a baculovirus vector system: a recombinant vaccine for mink enteritis parvovirus in mink

Abstract

The VP-2 gene of mink enteritis parvovirus (MEV) was amplified by the polymerase chain reaction using MEV DNA isolated from the faeces of a naturally infected mink. Subsequently the VP-2 gene was cloned into a baculovirus expression vector. Recombinant baculoviruses were isolated and the MEV VP-2 gene product was characterized after expression in St9 insect cells. The MEV VP-2 product had the same size as that reported for the wild-type MEV VP-2 protein and was recognized by convalescent sera from MEV-infected mink and a panel of monoclonal antibodies reactive to MEV. Furthermore, the VP-2 protein was able to form parvovirus-like particles, which had haemagglutinating properties comparable with the wild-type MEV. The cloned VP-2 gene was sequenced and only five nucleotide differences were found after alignment with the known sequences of the MEV type 1 and type 2 isolates. Surprisingly, the VP-2 gene encoded a valine and a tyrosine at amino acid positions 232 and 234, identical to the situation found in MEV type 1, but at position 300 there was a valine which is a determinant of MEV type 2. Immunization of mink with approximately 40000 haemagglutinating units of recombinant MEV VP-2 induced a measurable antibody response as tested by haemagglutination inhibition. Furthermore, the immunized mink did not excrete virus and did not develop clinical disease upon challenge with a virulent isolate of MEV.

Expression of Muscovy Duck Parvovirus Capsid Proteins (VP2 and VP3) in a Baculovirus Expression System and Demonstration of Immunity Induced by the Recombinant Proteins

“…Similar observations have been reported for the formation of VLPs of AAV2 (Ruffing et al, 1992) and some autonomous parvoviruses (Kajigaya et al, 1991;Martinez et al, 1992;Saliki et al, 1992;Christensen et al, 1993Christensen et al, , 1994.…”

“…When expressed using such a system, parvovirus capsid proteins self-assemble and form empty virus-like particles (VLPs). In most cases, the recombinant particles were shown to be antigenically and immunologically identical to native parvovirus virions (Kajigaya ef al., 1991;Lopez de Turiso et al, 1992;Martinez et al, 1992;Saliki et al, 1992;Christensen et al, 1994). The purpose of this paper is (i) to describe the cloning and the expression in baculovirus of the _~15 c. DPV gene encoding VP2 and VPd, and (ii) to demonstrate the antigenicity and the immunogenicity of the expressed proteins.…”

Identification of Aleutian Mink Disease Parvovirus Capsid Sequences Mediating Antibody-Dependent Enhancement of Infection, Virus Neutralization, and Immune Complex Formation

“…Thus, our results provide possible explanations for the failure of capsid-based ADV vaccines (1,52). As noted in the introduction, capsid-based vaccines against MEV are highly effective in mink (22,39). In fact, peptide vaccines based on the MEV capsid sequence also induce neutralizing antibodies and confer protection (39).…”

“…Capsid-based vaccines against MEV promptly induce neutralizing antibody and prevent infection and disease (22,39). In addition, persistent infections do not develop.…”

Causes of mortality in farmed mink in the Intermountain West, North America

“…None developed clinical signs, while 71% of control unvaccinated mink developed clinical signs. 5 The major control measure for MEV is vaccination. The mink producers in the cooperative in Utah and the Intermountain West routinely immunize 8-week-old kits for MEV with a single-dose modified live vaccine.…”