A modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccine protects late-term pregnancy gilts against a heterologous PRRSV-2 challenge.

The objective of this study was to evaluate the efficacy of a modified-live virus (MLV) porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against a heterologous PRRSV-2 challenge in late-term pregnancy gilts under experimental conditions. Eighteen gilts were randomly assigned to vaccinated-challenged, unvaccinated-challenged, and unvaccinated-unchallenged groups (n = 6 gilts per group). Pregnant gilts in the vaccinated-challenged and unvaccinated-unchallenged groups were able to carry their pregnancies to full term and farrowed after 114 to 115 days of gestation. In contrast, pregnant gilts in the unvaccinated-challenged group did not reach full term and farrowed early, after 104 to 108 days of gestation. Pregnant gilts vaccinated with the PRRSV-2 MLV vaccine exhibited a reduction in PRRSV-2 viremia. At the time of challenge with PRRSV-2, vaccinated gilts had relatively low levels of neutralizing antibody titers (≤ 1:16 titer), whereas the number of interferon-γ-secreting cells (IFN-γ-SC) was consistently at protective levels (IFN-γ-SC, ≥ 150 per million). Induction of cell-mediated immunity, as measured by PRRSV-2-specific IFN-γ-SC, correlated with a reduction in PRRSV-2 viremia. Duration of immunity was a minimum of 19 wk. Taken together, the results presented here suggest that vaccination of gilts with a PRRSV-2 MLV vaccine can protect against a heterologous PRRSV-2 challenge and improve the reproductive performance of late-term pregnancy gilts.

L'objectif de la présente étude était d'évaluer dans des conditions expérimentales l'efficacité d'un vaccin à virus vivant modifié (MLV) du virus du syndrome reproducteur et respiratoire porcin (PRRSV) contre une infection défi avec un PRRSV-2 hétérologue chez des cochettes en fin de gestation. Dix-huit cochettes furent assignées de manière aléatoire à un des groupes suivants: vaccinées-infectées, non-vaccinées-infectées et non-vaccinées-non-infectées (n = 6 cochettes par groupe). Les cochettes gestantes dans les groupes vaccinées-infectées et non-vaccinées-non-infectées furent en mesure de mener leur gestation à terme et ont mis-bas après 114 à 115 jours de gestation. À l'opposé, les cochettes gestantes du groupe (témoin) non-vaccinées-infectées ne se sont pas rendues à terme et ont mis-bas plus tôt, après 104 à 108 jours de gestation. Les cochettes gestantes vaccinées avec le vaccin PRRSV-2 MLV ont montré une réduction de la virémie à PRRSV-2. Au moment de l'infection-défi avec le PRRSV-2, les cochettes vaccinées avaient des titres relativement bas d'anticorps neutralisants (titre ≤ 1:16), alors que le nombre de cellules secrétant de l'interféron-γ (IFN-γ-SC) était constamment à des niveaux de protection (IFN-γ-SC, ≥ 150 par million). L'induction de l'immunité à médiation cellulaire, telle que mesurée par l'IFN-γ-SC spécifique à PRRSV-2, corrélait avec une réduction de la virémie à PRRSV-2. La durée de l'immunité était d'un minimum de 19 sem. Pris dans son ensemble, les résultats présentés ici suggèrent que la vaccination des cochettes avec un vaccin PRRSV-2 MLV peut protéger contre une infection-défi avec un PRRSV-2 hétérologue et améliorer les performances de reproduction des cochettes en fin de gestation.(Traduit par Docteur Serge Messier).

Comparative study of the virulence of 3 major Korean porcine circovirus type 2 genotypes (a, b, and d).

The objective of this study was to compare the virulence of 3 major Korean porcine circovirus type 2 (PCV2) genotypes in terms of clinical signs, PCV2 viremia and antibody titers, lymphoid lesions, and PCV2-antigen within lymphoid lesions in experimentally infected pigs. Pigs were infected at 7 weeks with PCV2a, PCV2b, and PCV2d strains and necropsied at 28 days post-infection. No statistical differences were observed in clinical signs, PCV2 viremia and antibody titers, lymphoid lesions scores, and numbers of PCV2 antigens among the 3 major Korean PCV2 genotypes. The results of this study indicate that the 3 major Korean PCV2 genotypes, PCV2a, PCV2b, and PCV2d, have similar virulence.

L'objectif de la présente étude était de comparer la virulence de trois génotypes majeurs de circovirus porcine de type 2 (PCV2) coréens en termes de signes cliniques, virémie de PCV2 et titres d'anticorps, lésions lymphoïdes et antigènes de PCV2 à l'intérieur des lésions lymphoïdes chez des porcs infectés expérimentalement. Les porcs furent infectés à 7 semaines d'âge avec les souches PCV2a, PCV2b et PCV2d et soumis à une nécropsie 28 jours post-infection. Aucune différence significative ne fut observée dans les signes cliniques, la virémie de PCV2 et les titres d'anticorps, les pointages de lésions lymphoïdes et les nombres d'antigènes de PCV2 pour les trois génotypes majeurs de PCV2 coréens. Les résultats de cette étude indiquent que les trois génotypes majeurs de PCV2 coréens, PCV2a, PCV2b et PCV2d ont une virulence similaire.(Traduit par Docteur Serge Messier).

A comparison of two commercially available porcine reproductive and respiratory syndrome virus (PRRSV) modified-live virus vaccines analyzing the growth performance in 1-day-old vaccinated swine located on endemic farms co-circulating PRRSV-1 and PRRSV-2.

The objective of this study was to compare the efficacy of a porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 modified-live virus (MLV) vaccines when administered at 1 day of age under field conditions. The piglets elicited anti-PRRSV antibodies at 1 day of age even in the presence of maternally derived antibodies. The number of PRRSV-2 genomic copies in the sera of pigs from the PRRSV-2 MLV-vaccinated pigs was significantly (P<0.05) lower when compared to PRRSV-1 MLV-vaccinated pigs. The average daily gain in PRRSV-2 MLV-vaccinated pigs was significantly (P<0.05) higher when compared to both PRRSV-1 MLV-vaccinated and unvaccinated pigs. This study demonstrated that vaccination as early as 1 day of age was effective against PRRSV infection.

Efficacy of concurrent vaccination with modified-live PRRSV-1 and PRRSV-2 vaccines against heterologous dual PRRSV-1 and PRRSV-2 challenge in late term pregnancy gilts.

The objective of this study was to evaluate the effect of concurrent vaccination with a porcine reproductive and respiratory syndrome virus (PRRSV)-1 modified-live virus (MLV) vaccine and a PRRSV-2 MLV vaccine against a dual heterologous PRRSV-1 and PRRSV-2 challenge in late term pregnancy gilts. Gilts were concurrently administered PRRSV-1 and PRRSV-2 MLV vaccines at 21 days prior to breeding at separate anatomical sites and were inoculated intranasally with both PRRSV types at 93 days of gestation. Vaccinated gilts had a higher number of live-born and weaned pigs, and a decrease in stillbirths compared to the unvaccinated control group following a dual challenge. Concurrent vaccination resulted also in the reduction of both PRRSV-1 and PRRSV-2 viremia which correlated with an increase in the number of PRRSV-1 and PRRSV-2 specific interferon-γ secreting cells (IFN-γ-SC). We believe the T cell responses contributed to the reduction of both PRRSV-1 and PRRSV-2 viremia. The results presented here demonstrate that concurrent vaccination with PRRSV-1 and PRRSV-2 MLV vaccines improves reproductive performance, reduces viremia of PRRSV-1 and PRRSV-2, and induces protective T cell reactions against dual PRRSV-1 and PRRSV-2 challenge in late term pregnancy gilts without local and systemic adverse reactions related to concurrent vaccination.

Evaluation of the efficacy of a trivalent vaccine mixture against a triple challenge with Mycoplasma hyopneumoniae, PCV2, and PRRSV and the efficacy comparison of the respective monovalent vaccines against a single challenge.

BACKGROUND: The objective of this study was to assess the efficacy of a trivalent vaccine mixture and compare it to the respective monovalent vaccines against Mycoplasma hyopneumoniae, porcine circovirus type 2 (PCV2), and porcine reproductive and respiratory syndrome virus (PRRSV). RESULTS: Pigs that were triple challenged with M. hyopneumoniae, PCV2, and PRRSV following vaccination with the trivalent vaccine mixture exhibited a significantly better growth performance when compared to unvaccinated and challenged pigs. A statistical difference was not found when comparing pig populations which were vaccinated with the trivalent vaccine followed by a triple challenge and pigs vaccinated with monovalent M hyopneumoniae vaccine followed by mycoplasmal single challenge in the following areas: M. hyopneumoniae nasal shedding, the number of M. hyopneumoniae-specific interferon-γ secreting cells (IFN-γ-SC), and mycoplasmal lung lesion scores. Pigs vaccinated with the trivalent vaccine mixture followed by a triple challenge resulted in a similar reduction of PCV2 viremia, an increase in the number of PCV2-specific IFN-γ-SC and reduction in interstitial lung lesion scores when compared to pigs vaccinated with a PCV-2 vaccine and challenged with PCV2 only. Lastly, there was a significant difference in the reduction of PRRSV viremia, an increase in PRRSV-specific IFN-γ-SC and a reduction of interstitial lung lesion scores between pigs vaccinated with the trivalent vaccine mixture followed by a triple challenge and pigs vaccinated with a monovalent PRRSV vaccine followed by PRRSV challenge only. CONCLUSION: The trivalent vaccine mixture was efficacious against a triple challenge of M. hyopneumoniae, PCV2, and PRRSV. The trivalent vaccine mixture, however, did not result in equal protection when compared against each respective monovalent vaccine, with the largest vaccine occurring within PRRSV.

Effectiveness of a commercial porcine reproductive and respiratory syndrome virus (PRRSV) subunit vaccine against heterologous PRRSV-1 and PRRSV-2 challenge in late-term pregnant gilts.

The objective of the present study was to evaluate the efficacy of a commercial porcine reproductive and respiratory syndrome virus (PRRSV) subunit vaccine against heterologous PRRSV-1 and PRRSV-2 challenge in late-term pregnant gilts. Gilts were vaccinated intramuscularly 56 and 35 days antepartum (on days 58 and 79 of gestation) and challenged intranasally 21 days antepartum (on day 93 of gestation) with PRRSV-1 or PRRSV-2. Regardless of the challenge strain's genotype, the vaccinated gilts carried their pregnancies to term and farrowed between days 114 and 115 of gestation. All the unvaccinated gilts aborted, between days 105 and 110 of gestation. The vaccinated gilts had a significantly lower level (P < 0.05) of PRRSV viremia and significantly higher levels (P < 0.05) of virus-neutralizing antibodies and interferon-γ-secreting cells compared with the unvaccinated gilts. The mean number of PRRSV-positive cells per area of fetal tissue examined did not differ significantly between the litters from the vaccinated and unvaccinated gilts. The data presented here indicate that vaccination in late-term pregnancy with PRRSV subunit vaccine is efficacious against reproductive failure due to heterologous PRRSV-1 and PRRSV-2 infection.

L'objectif de la présente étude était d'évaluer l'efficacité d'un vaccin sous-unitaire commercial contre le virus du syndrome reproducteur et respiratoire porcin (VSRRP) lors d'une infection défi avec des souches de VSRRP-1 et VSRRP-2 hétérologues chez des cochettes en fin de gestation. Les cochettes furent vaccinées par voie intramusculaire 56 et 35 jours ante-partum (aux jours 58 et 79 de la gestation) et infectées par voie intra-nasale 21 jours ante-partum (jour 93 de la gestation) avec VSRRP-1 ou VSRRP-2. Sans égard au génotype de la souche utilisée pour l'infection défi, les cochettes vaccinées ont mené leur gestation à terme et ont mis-bas entre les jours 114 et 115 de la gestation. Toutes les cochettes non-vaccinées ont avorté, entre les jours 105 et 110 de gestation. Les cochettes vaccinées avaient un niveau significativement plus faible (P < 0,05) de virémie à VSRRP et des niveaux significativement plus élevés (P < 0,05) d'anticorps viraux neutralisants et de cellules secrétant de l'interféron-γ comparativement aux cochettes non-vaccinées. Le nombre moyen de cellules positives pour VSRRP par surface de tissu foetal examiné ne différait pas significativement entre les portées des cochettes vaccinées et non-vaccinées. Les résultats présentés ici indiquent que la vaccination en fin de gestation avec un vaccin sous-unitaire anti-VSRRP est efficace contre les problèmes reproducteurs causés par une infection par des souches hétérologues de VSRRP-1 et VSRRP-2.(Traduit par Docteur Serge Messier).

A comparative study of the efficacy of a porcine reproductive and respiratory syndrome subunit and a modified-live virus vaccine against respiratory diseases in endemic farms.

The efficacy of a porcine reproductive and respiratory syndrome (PRRS) subunit vaccine was evaluated and compared with a modified-live virus (MLV) vaccine under field conditions. Three farms were selected based on their history of respiratory diseases caused by co-infection with both PRRSV-1 and PRRSV-2. In each farm, 60 pigs were randomly allocated to 2 vaccinated and 1 unvaccinated groups (20 pigs per group). One group of pigs were administered the PRRS subunit vaccine at 21 and 42 days of age and another group administered the PRRS MLV vaccine at 21 days of age. The subunit vaccine had similar efficacy and, in some instances, performed even better than the MLV vaccine. Vaccination of pigs with either of the PRRS vaccines resulted in significantly improved growth performance in Farm B but not in Farm C. In Farm A, pigs vaccinated with the PRRS subunit vaccine had a better growth performance statistically compared to those vaccinated with the PRRS MLV vaccine. At the peak of PRRSV-1 and PRRSV-2 viremia, neutralizing antibodies and T-cell responses against PRRSV-1 and PRRSV-2 were at low levels suggesting that either vaccine is only able to provide a partial protection against co-circulating PRRSV-1 and PRRSV-2.

L'efficacité d'un vaccin sous-unitaire contre le syndrome reproducteur et respiratoire porcin (SRRP) a été évaluée et comparée à un vaccin vivant modifié (VVM) dans des conditions de terrain. Trois fermes furent sélectionnées sur la base de leur historique de maladies respiratoires causées par co-infection par VSSRP-1 et VSRRP-2. Sur chaque ferme, 60 porcs furent répartis de manière aléatoire à deux groupes vaccinés et un groupe non-vacciné (20 porcs par groupe). Un groupe de porcs a reçu le vaccin SRRP sous-unitaire à 21 et 42 j d'âge et un autre groupe a reçu le VVM SRRP à 21 j d'âge. Le vaccin sous-unitaire avait une efficacité similaire, et en certaines occasions, performait mieux que le VVM. La vaccination des porcs avec un ou l'autre des vaccins SRRP, a résulté en une amélioration significative des performances de croissance pour la Ferme B mais pas pour la Ferme C. Sur la Ferme A, les porcs vaccinés avec le vaccin sous-unitaire SRRP présentaient de meilleures performances de croissance comparativement à ceux vaccinés avec le VVM du SRRP. Au pic de la virémie de VSRRP-1 et VSRRP-2, les réponses en anticorps neutralisants et en cellules T contre VSRRP-1 et VSRRP-2 étaient faibles ce qui suggère que les deux vaccins ne sont en mesure que de fournir une protection partielle contre une co-infection par VSRRP-1 et VSRRP-2.(Traduit par Docteur Serge Messier).

Evaluation of a porcine circovirus type 2a (PCV2a) vaccine efficacy against experimental PCV2a, PCV2b, and PCV2d challenge.

The objective of this study was to compare the efficacy of a commercial porcine circovirus type 2a (PCV2a) subunit vaccine against experimental PCV2a, PCV2b, and PCV2d challenge. A total of 105 pigs were randomly divided into 7 groups (15 pigs per group). At 21 days old the pigs were intramuscularly administered the PCV2a vaccine as a 1.0 mL dose. Four weeks following vaccination, pigs were challenged with either Korean PCV2a, PCV2b, or PCV2d. All vaccinated pigs showed a significant (P < 0.05) reduction of clinical signs, PCV2 viremia, lymphoid lesions, and lymphoid PCV2 antigen levels compared to unvaccinated control pigs. Vaccination resulted also in significantly higher (P < 0.05) titers of neutralizing antibody against PCV2, and an increase in the frequency of PCV2-specific interferon-γ secreting cells (IFN-γ-SC). The vaccine showed similar protection among the vaccinated groups regardless of the genotype of the challenge. Interestingly, vaccinated pigs had higher levels of neutralizing antibody titers against PCV2a compared to PCV2b or PCV2d while the number of PCV2a-, PCV2b-, and PCV2d-specific IFN-γ-SC were similar. Taken together, the results presented here demonstrate that a PCV2a vaccine can be effective against experimental PCV2a, PCV2b, and PCV2d challenge.

Comparison of four commercial PRRSV MLV vaccines in herds with co-circulation of PRRSV-1 and PRRSV-2.

The efficacy of four commercial porcine reproductive and respiratory syndrome virus (PRRSV) modified-live virus (MLV) vaccines against respiratory disease was evaluated and compared in pig farms suffering from co-infection with PRRSV-1 and PRRSV-2. All vaccinated groups on average exhibited improved growth rate compared to the unvaccinated pigs. Interestingly, the two groups vaccinated with either of the PRRSV-2 MLV vaccines had a better overall growth rate compared to the pigs vaccinated with either of the PRRSV-1 MLV vaccines. Vaccination of pigs with either of the PRRSV-1 MLV vaccines did not result in reduction of PRRSV-1 or PRRSV-2 viremia whereas vaccination of pigs with either of the PRRSV-2 MLV vaccines resulted in the reduction of PRRSV-2 viremia only. Taken together, the results of this field study demonstrate that a PRRSV-2 MLV vaccine can be efficacious against respiratory disease caused by co-infection with PRRSV-1 and PRRSV-2.

Comparison of 4 commercial modified-live porcine reproductive and respiratory syndrome virus (PRRSV) vaccines against heterologous Korean PRRSV-1 and PRRSV-2 challenge.

The efficacy of 4 commercial porcine reproductive and respiratory syndrome virus (PRRSV) modified-live vaccines (MLV), against PRRSV-1 and PRRSV-2 was evaluated and compared in growing pigs. Two of the vaccines were based on PRRSV-1 and two on PRRSV-2. There were no significant differences between each of the two PRRSV-1 MLV vaccines and the two PRRSV-2 MLV vaccines respectively based on virology, immunological, and pathological evaluations. Vaccination with either of the PRRSV-1 MLV vaccines resulted in reduced PRRSV-1 but not PRRSV-2 viremia. Additionally, vaccination with either of the PRRSV-1 MLV vaccines resulted in reduction of lung lesions and PRRSV-1 positive cells in PRRSV-1 challenged pigs but had no significant effect in PRRSV-2 challenged pigs. In contrast, vaccination with either of the two PRRSV-2 MLV vaccines resulted in the reduction of both PRRSV-1 and PRRSV-2 viremia. The PRRSV-2 MLV vaccines were also able to effectively reduce lung lesions and PRRSV positive cells after challenge with either PRRSV-1 or PRRSV-2. Our data suggest that while vaccination with PRRSV-1 MLV vaccines can be effective against PRRSV-1, only PRRSV-2 MLV vaccines can protect against both Korean PRRSV-1 and PRRSV-2 challenges in this study.

L'efficacité de quatre vaccins vivants modifiés (VVM) commerciaux contre le virus du syndrome reproducteur et respiratoire porcin (VSRRP), a été évaluée et comparée chez des porcs en croissance infectés expérimentalement avec VSRRP-1 et VSRRP-2. Deux des vaccins étaient à base de VSRRP-1 et deux à base de VSRRP-2. Il n'y avait pas de différence significative entre chacun des deux VVM VSRRP-1 et les deux VVM VSRRP-2 respectivement sur la base des évaluations virologiques, immunologiques et pathologiques. La vaccination avec l'un ou l'autre des VVM VSRRP-1 a entrainé une réduction de la virémie causée par VSRRP-1 mais pas par VSRRP-2. De plus, la vaccination avec l'un ou l'autre des VVM VSRRP-1 a permis une réduction des lésions pulmonaires et des cellules positives pour VSRRP-1 chez les porcs infectés avec VSRRP-1 mais n'a pas eu d'effet significatif chez les porcs infectés avec VSRRP-2. La vaccination avec l'un ou l'autre des VVM SRRP-2 a résulté en une réduction de la virémie autant pour VSRRP-1 que VSRRP-2. Les VVM VSRRP-2 étaient également en mesure de réduire efficacement les lésions pulmonaires et les cellules positives pour VSRRP après l'infection soit par le VSRRP-1 ou VSRRP-2. Nos résultats suggèrent que bien que la vaccination avec les VVM VSRRP-1 peuvent être efficaces envers VSRRP-1, seulement les VVM VSRRP-2 peuvent protéger contre les infections par les VSRRP-1 et VSRRP-2 coréens utilisés dans la présente étude.(Traduit par Docteur Serge Messier).

Cross-protection of a modified-live porcine reproductive and respiratory syndrome virus (PRRSV)-2 vaccine against a heterologous PRRSV-1 challenge in late-term pregnancy gilts.

We have evaluated the cross-protection of a modified-live virus (MLV) vaccine based on porcine reproductive and respiratory syndrome virus (PRRSV)-2, against a heterologous PRRSV-1 challenge in late term pregnancy gilts. Gilts were vaccinated 42 days prior to breeding and then challenged intranasally with PRRSV-1 at 93 days of gestation. No local or systemic adverse effects related to vaccination were observed in the vaccinated gilts throughout the study. Vaccination resulted in a longer gestation period, a higher number of live-born and weaned piglets, and a significant decrease in the number of stillborn piglets compared to the unvaccinated group. The PRRSV-2 MLV vaccine was also able to significantly reduce PRRSV-1 viremia. At the time of PRRSV-1 challenge, vaccinated gilts had significantly higher PRRSV-1 specific interferon-γ secreting cells but low neutralizing antibody titers against PRRSV-1 compared to unvaccinated gilts. This correlated with a reduction of PRRSV-1 viremia, indicating that cell-mediated rather than humoral immunity played a role in PRRSV-1 clearance from the blood. Fetal thymic tissues from vaccinated pregnant gilts had fewer PRRSV-1 positive cells compared to unvaccinated gilts. Taken together these results indicate that vaccination of gilts with PRRSV-2 MLV vaccine can provide cross-protection against PRRSV-1 challenge and improve reproductive performance.

Comparative evaluation of the efficacy of commercial and prototype PRRS subunit vaccines against an HP-PRRSV challenge.

The objective of this study was to compare the efficacy of a commercial porcine reproductive and respiratory syndrome (PRRS) subunit vaccine and a prototype PRRS II subunit vaccine against a highly pathogenic PRRS virus (HP-PRRSV) in pigs. Both vaccines were administered intramuscularly in 2 doses at 21 and 42 days of age, and the pigs were challenged intranasally with HP-PRRSV at 63 days of age. Pigs vaccinated with the prototype PRRS II subunit vaccine had significantly higher anti-PRRSV antibody titers, a greater number of interferon-γ-secreting cells, and a greater reduction in lung lesion scores compared to pigs vaccinated with the commercial PRRS subunit vaccine. Therefore, the commercial PRRS subunit and prototype PRRS II subunit vaccines are efficacious against HP-PRRSV.

A comparison of the severity of reproductive failure between single and dual infection with porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 in late-term pregnancy gilts.

The objective of this study was to compare the severity of reproductive failure caused by either a single or a dual infection with porcine reproductive and respiratory syndrome virus (PRRSV)-1 and PRRSV-2 in late-term pregnancy gilts. Pregnant gilts were intranasally administered PRRSV-1, PRRSV-2 or both at 3 weeks before the expected farrowing date (93 days of gestation). Regardless of single and dual infection, PRRSV-infected pregnant gilts experienced premature farrowing (103-109 days of gestation) compared with negative control gilts which carried their pregnancy to full term (114-115 days of gestation). Pregnant gilts infected with only PRRSV-1 had a significantly (p < 0.05) higher number of genomic copies of PRRSV-1 in their blood compared with dually infected gilts. Additionally, stillborn foetuses and live-born piglets from pregnant gilts infected with only PRRSV-1 had a significantly (p < 0.05) higher number of PRRSV-1-positive cells per unit area of tissue sections examined, compared to pregnant gilts dually infected with PRRSV-1 and PRRSV-2. In contrast, pregnant gilts infected with only PRRSV-2 showed no difference in the number of genomic copies of PRRSV-2 compared with dually infected pregnant gilts and there were no significant differences in PRRSV-2-positive cells per unit area in tissues of stillborn foetuses and live-born piglets from pregnant gilts infected with PRRSV-2 only compared with dually infected gilts. Interestingly, even though PRRSV-2 was shown to replicate more efficiently compared with PRRSV-1 in dually infected pregnant gilts, neither PRRSV type was able to exacerbate reproductive failure in pregnant gilts already dually infected with PRRSV-1 and PRRSV-2. Our results suggest that the severity of reproductive failure is similar between dual (PRRSV-1 and PRRSV-2) and single infection (PRRSV-1 or PRRSV-2).

Evaluation of the efficacy of a novel porcine circovirus type 2 synthetic peptide vaccine.

A novel porcine circovirus type 2 (PCV2) peptide vaccine comprised of a consensus capsid (Cap) protein domain encoded by open reading frame 2 was developed to control PCV2 infection. The efficacy of the vaccine was evaluated against a commercial baculovirus-expressed recombinant PCV2 subunit vaccine based on the Cap protein. The amino acid sequence of this Cap protein was designed based on the alignment of amino acid sequences from different isolates from Europe, North America, and Asia. The vaccine was evaluated in either phosphate-buffered saline or adjuvanted with aluminum hydroxide, cobalt oxide, or liposome. Overall the PCV2 peptide vaccine was less efficacious against PCV2 challenge compared with the commercial PCV2 vaccine. The peptide vaccine was the most efficacious when liposome was used as an adjuvant, significantly (P < 0.05) reducing viremia while increasing the levels of neutralizing antibodies and interferon-γ secreting cells. This suggests, in the presence of liposome, the peptide vaccine was able to elicit both humoral and cellular immune responses.

Un nouveau vaccin peptidique contre le circovirus porcin de type 2 (CVP2) contenant un domaine d'une protéine consensus de la capside (Cap) codé par le cadre de lecture ouvert 2 fut développé pour limiter l'infection par CVP2. L'efficacité du vaccin fut évaluée versus celle d'un vaccin commercial CVP2 sous-unitaire recombinant s'exprimant dans un baculovirus et basé sur la protéine Cap. La séquence en acides aminés de cette protéine Cap a été élaborée basée sur l'alignement des séquences d'acides aminés provenant de différents isolats d'Europe, d'Amérique du Nord, et d'Asie. Le vaccin a été évalué dans soit de la saline tamponnée avec du phosphate ou dans un adjuvant contenant de l'hydroxyde d'aluminium, d'oxyde de cobalt, ou des liposomes. Globalement, le vaccin peptidique CVP2 était moins efficace contre une infection défi par CVP2 comparativement au vaccin commercial. Le vaccin peptidique était le plus efficace lorsque les liposomes étaient utilisés comme adjuvant, réduisant de manière significative (P < 0,05) la virémie tout en augmentant la quantité d'anticorps neutralisants et de cellules secrétant de l'interféron γ. Ceci suggère qu'en présence de liposomes le vaccin lipidique était en mesure d'induire des réponses immunitaires humorale et cellulaire.(Traduit par Docteur Serge Messier).

Effect of vaccination with a porcine reproductive and respiratory syndrome subunit vaccine on sow reproductive performance in endemic farms.

The objective of this field study was to evaluate the reproductive performance of sows after vaccination with a porcine reproductive and respiratory syndrome (PRRS) subunit vaccine (PRRSFREE PRRS subunit vaccine, Reber Genetics, Taiwan, Republic of China) under field conditions. The study was performed in three farms with endemic infections with both PRRS virus (PRRSV)-1 and PRRSV-2, a situation representative of most Korean farms. Pregnant sows were immunised intramuscularly with 2.0 ml of the PRRS subunit vaccine at 58 and 79 days of gestation (eight and five weeks antepartum) according to the manufacturer's recommendation. Vaccination did not result in any observed adverse reaction. Vaccinated sows exhibited a significant improvement in reproductive performance (reduction of abortions) and litter characteristics (increase of weaned pigs) compared with unvaccinated sows. Vaccinated sows had significantly (P<0.05) higher PRRSV ELISA sample/positive ratio and number of PRRSV-specific interferon-γ-secreting cells compared with the unvaccinated control group. The results of this study demonstrate that the PRRS subunit vaccine can improve the reproductive performance of sows in farms with endemic PRRSV infection.

Comparison of 3 vaccination strategies against porcine reproductive and respiratory syndrome virus, Mycoplasma hyopneumoniae, and porcine circovirus type 2 on a 3 pathogen challenge model.

The objective of this study was to compare clinical, microbiologic, immunologic, and pathologic parameters in pigs each concurrently administered porcine reproductive and respiratory syndrome virus (PRRSV), Mycoplasma hyopneumoniae, and porcine circovirus type 2 (PCV2) vaccine from 1 of 2 commercial sources at 21 days of age and challenged with field strains of each of the 3 pathogens. Pigs were challenged with PRRSV and M. hyopneumoniae at 42 days of age (-14 days post-challenge, dpc) followed by a challenge with PCV2 at 56 days of age (0 dpc). Significant differences were observed between vaccinated challenged and unvaccinated challenged groups in clinical (average daily gain and clinical signs), microbiologic (viremia and nasal shedding), immunologic (antibodies and interferon-γ secreting cells), and pathologic (lesions) outcomes. Significant differences were observed among the 3 vaccinated challenged groups in microbiologic (nasal shedding of M. hyopneumoniae and viremia of PCV2) and immunologic (M. hyopneumoniae- and PCV2-specific interferon-γ secreting cells) outcomes. The vaccination regimen for PRRSV vaccine, M. hyopneumoniae vaccine, and PCV2 vaccine is efficacious for controlling triple challenge with PRRSV, M. hyopneumoniae, and PCV2 from weaning to finishing period.

L'objectif de la présente étude était de comparer les paramètres cliniques, microbiologiques, immunologiques et pathologiques chez des porcs qui ont chacun été vaccinés de façon concomitante à 21 jours d'âge contre le virus du syndrome reproducteur et respiratoire porcin (VSRRP), Mycoplasma hyopneumoniae, et le circovirus porcin de type 2 (CVP2) provenant d'une de deux sources commerciales et soumis à une infection défi avec des souches de champs de chacun des trois agents pathogènes. Les porcs ont été infectés avec le VSRRP et M. hyopneumoniae à 42 jours d'âge (−14 jours post-infection, jpi) suivi d'une infection par le CVP2 à 56 jours d'âge (0 jpi). Des différences significatives ont été observées entre les groupes vaccinés et infectés et les groupes non-vaccinés infectés pour ce qui est résultats cliniques (gain moyen quotidien et signes cliniques), microbiologiques (virémie et excrétion nasale), immunologiques (anticorps et cellules secrétant de l'interféron-γ), et pathologiques (lésions). Des différences significatives ont été observées entre les trois groupes d'animaux vaccinés et infectés pour ce qui est des résultats microbiologiques (excrétion nasale de M. hyopneumoniae et virémie de CVP2) et immunologiques (cellules secrétant de l'interféron-γ spécifiques à M. hyopneumoniae et CVP2). Le protocole de vaccination pour le vaccin VSRRP, le vaccin M. hyopneumoniae, et le vaccin CVP2 est efficace pour la maitrise d'une infection triple avec le VSRRP, M. hyopneumoniae, et CVP2 à partir du sevrage jusqu'à la période de finition.(Traduit par Docteur Serge Messier).

Vaccination with a porcine reproductive and respiratory syndrome virus vaccine at 1-day-old improved growth performance of piglets under field conditions.

A porcine reproductive and respiratory syndrome virus (PRRSV) modified live-virus (MLV) vaccine was evaluated under field conditions for registration as recommended by the Republic of Korea's Animal, Plant & Fisheries Quarantine & Inspection Agency. A single dose of the vaccine was administered to 1-day-old piglets and their growth performance was monitored under field conditions. Three separate farms were selected based on their history of PRRSV-associated respiratory diseases. On each farm, 40 pigs were randomly allocated to one of two treatment groups: (i) vaccinated (n = 20) and (ii) unvaccinated (n = 20) pigs at 1 day of age. Vaccinated pigs showed an increase of their market weight of 6.23 kg/pig compared to the unvaccinated pigs (98.01 kg in vaccinated group vs. 91.78 kg in unvaccinated group; P < 0.05) and exhibited a decrease in mortality rate by 6.7% (3.3% in vaccinated group vs. 10% in unvaccinated group; P < 0.05). The pigs had a sufficiently mature immune system for the vaccine to elicit humoral and cell-mediated immunity (as measured by anti-PRRSV antibodies and PRRSV-specific interferon-γ secreting cells, respectively) at 1 day of age even in the presence of maternally derived antibodies. The results presented in this study demonstrate that the PRRSV MLV vaccine is effective in improving growth performance from day 1 all the way to day 182 in endemic farms suffering with PRRSV-2 infection or both PRRSV-1 and PRRSV-2 infection.

Commercial porcine reproductive and respiratory syndrome virus (PRRSV)-2 modified live virus vaccine against heterologous single and dual Korean PRRSV-1 and PRRSV-2 challenge.

This study evaluated porcine reproductive and respiratory syndrome virus (PRRSV)-2 modified live virus (MLV) vaccine against heterologous single and dual challenge of Korean PRRSV-1 and PRRSV-2. Pigs were administered PRRSV-2 MLV vaccine intramuscularly at 21 days of age and inoculated intranasally with both genotypes at 56 days of age. Vaccination of pigs with PRRSV-2 MLV vaccine resulted in reduction of viral loads of both PRRSV-1 and PRRSV-2 after heterologous single and dual challenge with PRRSV-1 and PRRSV-2. In addition, pigs vaccinated with PRRSV-2 MLV vaccine exhibited higher frequencies of PRRSV-1 and PRRSV-2 specific interferon-γ secreting cells (IFN-γ-SC) and showed a significant reduction in lung lesions and PRRSV nucleic acid within the lung lesions after single and dual challenge compared with unvaccinated challenged pigs. Taken together these results demonstrated that vaccination of pigs with PRRSV-2 is efficacious in protecting growing pigs from respiratory disease against heterologous single and dual PRRSV-1 and PRRSV-2 challenge.

Evaluation of the effect of a porcine reproductive and respiratory syndrome (PRRS) modified-live virus vaccine on sow reproductive performance in endemic PRRS farms.

The efficacy of a porcine reproductive and respiratory syndrome (PRRS) modified-live virus vaccine in reproductive performance was evaluated under field conditions. Three PRRS endemic farms were selected based on their history of PRRS-associated reproductive failures. On each farm, a total of 40 sows were randomly allocated to either vaccinated (n=20) or unvaccinated (n=20) groups. Sows were vaccinated six weeks prior to breeding. Clinical data showed a significant improvement in reproductive performance in vaccinated sows. Sows in the vaccinated groups had a significantly (P<0.05) reduced number of stillborn piglets in all 3 farms. Sows in the vaccinated groups also had a significantly (P<0.05) higher number of live-born piglets in one of the farms. Sows in the vaccinated groups had a significantly (P<0.05) higher number of weaned piglets in two of the farms. Premature farrowing, one of the late gestation symptoms of PRRS, was also reduced due to vaccination as suggested by the increase in gestation length and the reduction in the number of stillborn piglets. No adverse systemic or local side effects relative to vaccination were observed during the entire gestation. No vaccine strain was detected in the vaccinated sows from all three farms at 70 and 114days post vaccination and in live-born piglets at the time of farrowing. Vaccination of sows with this PRRS vaccine was effective in improving reproductive performance in endemic PRRS farms.

Development of porcine circovirus 2 (PCV2) open reading frame 2 DNA vaccine with different adjuvants and comparison with commercial PCV2 subunit vaccine in an experimental challenge.

The objective of this study was to compare the protection against challenge with porcine circovirus 2 (PCV2) induced by an experimental vaccine based on open reading frame (ORF) 2 of PCV2 DNA plus an adjuvant (aluminum hydroxide, cobalt oxide, or liposome) and a commercial PCV2 subunit vaccine. A total of 35 colostrum-fed, cross-bred, conventional piglets were randomly divided into 7 groups. The commercial vaccine was more efficacious against PCV2 challenge than the 4 experimental vaccines according to immunologic, virologic, and pathological outcomes. The pigs inoculated with the experimental vaccine containing the liposome adjuvant had significantly higher levels (P < 0.05) of neutralizing antibodies and interferon-γ-secreting cells, and significantly lower levels (P < 0.05) of PCV2 viremia than the pigs inoculated with the other experimental vaccines. The pigs inoculated with the experimental vaccines containing either the liposome adjuvant or the cobalt oxide adjuvant had significantly lower lymphoid lesion scores (P < 0.05) than the pigs in the group inoculated with the PCV2 DNA vaccine dissolved in phosphate-buffered saline. Liposome proved to be a potent adjuvant that efficiently enhanced both humoral and cellular immune responses induced by the PCV2 DNA vaccine.

L'objectif de la présente étude était de comparer la protection contre une infection défi avec le circovirus porcin de type (CVP2) induite par un vaccin expérimental à base du cadre de lecture ouvert (ORF) 2 de l'ADN de CVP2 plus un adjuvant (hydroxyde d'aluminium, oxyde de cobalt, ou liposome) et un vaccin CVP2 sous-unitaire commercial. Un total de 35 porcelets croisés, conventionnels et nourris au colostrum ont été séparés de manière aléatoire en sept groupes. Le vaccin commercial était plus efficace contre l'infection par CVP2 que les quatre vaccins expérimentaux en fonction des résultats immunologiques, virologiques, et pathologiques. Les porcs inoculés avec le vaccin expérimental contenant l'adjuvant liposome avaient des titres significativement (P < 0,05) plus élevés d'anticorps neutralisants et un nombre significativement (P < 0,05) moindre de cellules secrétant de l'interféron-γ et une virémie à CVP2 que les porcs inoculés avec les autres vaccins expérimentaux. Les porcs inoculés avec les vaccins expérimentaux contenant l'adjuvant liposome ou oxyde de cobalt avaient des scores de lésions lymphoïdes significativement (P < 0,05) plus faibles que les porcs dans le groupe inoculé avec le vaccin ADN CVP2 dissout dans de la saline tamponnée. Les liposomes se sont avérés être un adjuvant puissant qui a augmenté de manière efficace autant la réponse immunitaire humorale que cellulaire induite par le vaccin à ADN CVP2.(Traduit par Docteur Serge Messier).