An octavalent vaccine provides pregnant gilts protection against a highly virulent porcine parvovirus strain.

BACKGROUND: Porcilis® Ery+Parvo+Lepto is an octavalent inactivated ready-to-use vaccine that contains Erysipelothrix rhusiopathiae (Ery), porcine parvovirus (PPV), and six serogroups of Leptospira (Lepto). The efficacy of Porcilis® Ery + Parvo+Lepto against reproductive problems associated with porcine parvovirus (PPV) infection was evaluated in pregnant gilts. For this, a group of ninegilts was vaccinated twice (at 5 and 6 months old) with Porcilis® Ery + Parvo+Lepto (Group 1), while a group of eight gilts was included as unvaccinated controls (Group 2). All pigs were artificially inseminated 4 weeks after the second vaccination. They were challenged during early gestation with PPV-27a, a virulent cluster D strain, and euthanized to collect their offspring by hysterectomy around day 90 in pregnancy. Antibody responses against PPV in gilts were measured, and the presence of PPV in progeny was also determined. RESULTS: No clinical signs were observed after vaccination. After PPV challenge, all foetuses from the vaccinated gilts were alive (132/132), while in the unvaccinated group only 41% were alive (46/112), 19.6% were dead and 39.4% of the offspring (44/112) were mummified. PPV could be detected by qPCR in 14% of the progeny from vaccinated gilts at an average of 4.7 log10/ml, whereas this was significantly higher in the control group, where 90% of the progeny were PPV positive, with titres of 9.8 log10/ml on average. CONCLUSIONS: The present study demonstrates that vaccination of gilts with Porcilis® Ery + Parvo+Lepto was safe and induced an immune response sufficient to protect progeny against PPV by reducing transplacental infection.

Cell Attachment Domains of the Porcine Epidemic Diarrhea Virus Spike Protein Are Key Targets of Neutralizing Antibodies.

Porcine epidemic diarrhea virus (PEDV) causes enteric disease in pigs, resulting in significant economic losses to the swine industry worldwide. Current vaccination approaches against this emerging coronavirus are only partially effective, though natural infection protects pigs against reinfection and provides lactogenic immunity to suckling piglets. The viral spike (S) glycoprotein, responsible for receptor binding and cell entry, is the major target for neutralizing antibodies. However, knowledge of antibody epitopes, their nature and location in the spike structure, and the mechanisms by which the antibodies interfere with infection is scarce. Here we describe the generation and characterization of 10 neutralizing and nonneutralizing mouse monoclonal antibodies raised against the S1 receptor binding subunit of the S protein. By expression of different S1 protein fragments, six antibody epitope classes distributed over the five structural domains of the S1 subunit were identified. Characterization of antibodies for cross-reactivity and cross-neutralization revealed antigenic differences among PEDV strains. The epitopes of potent neutralizing antibodies segregated into two epitope classes and mapped within the N-terminal sialic acid binding domain and in the more C-terminal receptor binding domain. Antibody neutralization escape mutants displayed single amino acid substitutions that impaired antibody binding and neutralization and defined the locations of the epitopes. Our observations picture the antibody epitope landscape of the PEDV S1 subunit and reveal that its cell attachment domains are key targets of neutralizing antibodies.IMPORTANCE Porcine epidemic diarrhea virus (PEDV), an emerging porcine coronavirus, causes an economically important enteric disease in pigs. Effective PEDV vaccines for disease control are currently lacking. The spike (S) glycoprotein on the virion surface is the key player in virus cell entry and, therefore, the main target of neutralizing antibodies. To understand the antigenic landscape of the PEDV spike protein, we developed monoclonal antibodies against the spike protein's S1 receptor binding region and characterized their epitopes, neutralizing activity, and cross-reactivity toward multiple PEDV strains. Epitopes of antibodies segregated into six epitope classes dispersed over the multidomain S1 structure. Monoclonal antibodies revealed antigenic variability in B-cell epitopes between PEDV strains. The epitopes of neutralizing antibodies mapped to two distinct domains in S1 that are involved in binding to carbohydrate and proteinaceous cell surface molecules, respectively, indicating the importance of these cell attachment sites on the PEDV spike protein in eliciting a protective humoral immune response.

In vivo assessment of equine arteritis virus vaccine improvement by disabling the deubiquitinase activity of papain-like protease 2.

Arteriviruses are a family of positive-stranded RNA viruses that includes the prototypic equine arteritis virus (EAV) and porcine reproductive and respiratory syndrome virus (PRRSV). Although several vaccines against these viruses are commercially available there is room for improvement, especially in the case of PRRSV. The ability of arteriviruses to counteract the immune response is thought to decrease the efficacy of the current modified live virus vaccines. We have recently shown that the deubiquitinase (DUB) activity of EAV papain-like protease 2 (PLP2) is important for the inhibition of innate immune activation during infection. A vaccine virus lacking PLP2 DUB activity may therefore be more immunogenic and provide improved protection against subsequent challenge than its DUB-competent counterpart. To test this hypothesis, twenty Shetland mares were randomly assigned to one of three groups. Two groups were vaccinated, either with DUB-positive (n=9) or DUB-negative (n=9) recombinant EAV. The third group (n=2) was not vaccinated. All horses were subsequently challenged with the virulent KY84 strain of EAV. Both vaccine viruses proved to be replication competent in vivo. In addition, the DUB-negative virus provided a similar degree of protection against clinical disease as its DUB-positive parental counterpart. Owing to the already high level of protection provided by the parental virus, a possible improvement due to inactivation of PLP2 DUB activity could not be detected under these experimental conditions. Taken together, the data obtained in this study warrant further in vivo investigations into the potential of using DUB-mutant viruses for the improvement of arterivirus vaccines.

Newcastle disease virus (NDV) marker vaccine: an immunodominant epitope on the nucleoprotein gene of NDV can be deleted or replaced by a foreign epitope.

The nucleoprotein (NP) of Newcastle disease virus (NDV) functions primarily to encapsidate the virus genome for the purpose of RNA transcription, replication, and packaging. This conserved multifunctional protein is also efficient in inducing NDV-specific antibody in chickens. Here, we localized a conserved B-cell immunodominant epitope (IDE) spanning residues 447 to 455 and successfully generated a recombinant NDV lacking the IDE by reverse genetics. Despite deletion of NP residues 443 to 460 encompassing the NP-IDE, the mutant NDV propagated in embryonated specific-pathogen-free chicken eggs to a level comparable to that of the parent virus. In addition, a B-cell epitope of the S2 glycoprotein of murine hepatitis virus (MHV) was inserted in-frame to replace the NP-IDE. Recombinant viruses properly expressing the introduced MHV epitope were successfully generated, demonstrating that the NP-IDE not only is dispensable for virus replication but also can be replaced by foreign sequences. Chickens immunized with the hybrid recombinants produced specific antibodies against the S2 glycoprotein of MHV and completely lacked antibodies directed against the NP-IDE. These marked-NDV recombinants, in conjunction with a diagnostic test, enable serological differentiation of vaccinated animals from infected animals and may be useful tools in ND eradication programs. The identification of a mutation-permissive region on the NP gene allows a rational approach to the insertion of protective epitopes and may be relevant for the design of NDV-based cross-protective marker vaccines.