Early administration of canine parvovirus monoclonal antibody prevented mortality after experimental challenge.

OBJECTIVE: To evaluate the effectiveness of canine parvovirus monoclonal antibody (CPMA) as a treatment against canine parvovirus (CPV-2)-induced mortality and to support USDA product licensure. ANIMALS: 28 purpose-bred Beagle dogs aged 8 weeks were randomized to the treated (n = 21) or control (7) group. METHODS: Dogs were challenged intranasally with 104.2 TCID50 virulent CPV-2b on Day 0 and monitored for 14 days for fecal viral shed and clinical disease. All dogs began shedding CPV-2 on Day 4 and were treated intravenously with a single dose of either CPMA (0.2 mL/kg) or saline (equal volume). No additional treatments were given to either group. Feces and sera were collected for quantitative analysis of fecal viral shed (hemagglutination) and antibody responses (hemagglutination inhibition and dot-blot ELISA), respectively. Dogs were monitored twice daily for parameters including lymphopenia, fever, vomiting, abnormal feces, inappetence, and lethargy. Humane endpoints triggered euthanasia by a veterinarian masked to treatment groups. The primary outcome variable was prevention of mortality as compared to controls. RESULTS: Mortality was prevented in all CPMA-treated dogs compared to 57% mortality in the control group (P = .0017, Fisher exact test). Canine parvovirus monoclonal antibody-treated dogs also experienced less severe and/or shorter durations of diarrhea, fever, vomiting, CPV-2 shedding in feces, and lymphopenia. Both groups showed similar immunoglobulin M responses as measured by semiquantitative analysis. CLINICAL RELEVANCE: Intravenous administration of CPMA can effectively improve clinical outcome when administered early in CPV-2 disease. Canine parvovirus monoclonal antibody treatment after proven infection does not interfere with adaptive immunity.

Initial vaccination and revaccination with Type I PRRS 94881 MLV reduces viral load and infection with porcine reproductive and respiratory syndrome virus.

BACKGROUND: Porcine reproductive and respiratory syndrome (PRRS) causes respiratory distress in pigs, reproductive failure in breeding-age gilts and sows, and can have devastating economic consequences in domestic herds. Several PRRS vaccines are available commercially. This study compared the effectiveness of single-vaccination and revaccination schedules using the PRRS 94881 Type I modified live virus (MLV) vaccine ReproCyc® PRRS EU with no vaccination (challenge control) in protecting against a PRRS virus (PRRSV) challenge in non-pregnant gilts. RESULTS: Data were available from 48 gilts across three groups: a challenge control group (n = 16), which received no vaccination; a revaccination group (n = 16), which received ReproCyc® PRRS EU on Days 0 and 56; and a single vaccination group (n = 16), which received ReproCyc® PRRS EU on Day 56. All gilts were PRRSV RNA-negative (based on reverse transcription and quantitative polymerase chain reaction [RT-qPCR]) and PRRSV seronegative (based on enzyme-linked immunosorbent assay [ELISA]) at Day 0. All gilts were challenged with PRRSV strain 190136 on Day 91.Viral RNA loads in both vaccination groups were significantly reduced compared with the challenge control group on Days 98 (P < 0.0001) and 101 (P < 0.0001), indicating that vaccinated gilts were better able to respond to challenge than unvaccinated gilts. At all timepoints following challenge, mean viral RNA load and the percentage of PRRSV RNA-positive gilts were numerically higher in the single-vaccination group than in the revaccination group; these differences were statistically significant on Day 101 (P = 0.0434). Furthermore, viremia levels after challenge were significantly lower in the revaccination group than in the single-vaccination group based on median area under the curve (AUC) values for viral RNA load from Day 91 to Day 112, suggesting that revaccinated gilts had better protection from viral infection than gilts who received a single vaccination. Protection from viremia did not correlate with the proportion of seropositive gilts on Day 91. In the single-vaccination group, 94% of pigs were seropositive on Day 91 compared with 56% in the revaccination group. Vaccination was well tolerated and no safety concerns were identified. CONCLUSIONS: Both single-vaccination and revaccination with ReproCyc® PRRS EU were effective in reducing PRRSV viremia post-challenge. These findings have important implications for herd management as both the single-vaccination and revaccination schedules protect against PRRSV challenge, with revaccination appearing to provide better protection from viremia than single vaccination.

Safety and early onset of immunity with a novel European porcine reproductive and respiratory syndrome virus vaccine in young piglets.

Porcine reproductive and respiratory syndrome virus (PRRSV) can be difficult to manage in commercial settings. A novel type I PRRSV vaccinal strain (94881) was evaluated for safety and efficacy/onset of immunity (OOI) in piglets. In 2 experiments, groups of piglets were vaccinated intramuscularly (IM) at approximately 14 d of age with a maximum-range commercial dose, an overdose, or a placebo in experiment 1 and either a minimum-range commercial dose or a placebo in experiment 2. The piglets in experiment 1 were evaluated for local and systemic reactions from days -2 through 14 after vaccination. The piglets in experiment 2 were challenged with a virulent heterologous type I PRRSV isolate 14 d after vaccination and observed once daily for general health from days -1 through 12 after vaccination and once daily for clinical signs associated with challenge from days 13 through 24 after vaccination. The average daily weight gain (ADWG) and the results of serologic and viremia testing were evaluated in experiments 1 and 2. Lung lesion scores and results of testing for PRRSV in lung tissue were evaluated in experiment 2. In experiment 1 the vaccine was shown to be safe, as there were no relevant differences between the vaccinated piglets and the piglets given a placebo. In experiment 2 the vaccine's efficacy, with an OOI of 14 d after vaccination, was established, as the vaccinated and challenged piglets exhibited significantly lower lung lesion scores, viremia, viral load in lung tissue, and total clinical sign scores, along with a significantly greater ADWG, compared with the placebo-vaccinated and challenged piglets.

La gestion du virus du syndrome reproducteur et respiratoire porcin (VSRRP) peut être difficile dans un environnement de production commerciale. Une nouvelle souche vaccinale du VSRRP de type 1 (94881) a été évaluée d'un point de vue sécurité et efficacité/début de l'immunité (DDI) chez des porcelets. Dans deux expériences, des groupes de porcelets ont été vaccinés par voie intramusculaire (IM) à l'âge d'environ 14 j avec une dose commerciale maximale, une surdose, ou un placebo dans l'expérience 1 et une dose commerciale minimale ou un placebo dans l'expérience 2. Les porcelets dans l'expérience 1 furent évalués pour des réactions locale et systémique à compter du jour −2 jusqu'au jour 14 post-vaccination. Les porcelets dans l'expérience 2 furent soumis à une infection défi avec un isolat virulent hétérologue de VSRRP de type 1 14 j après la vaccination et observés une fois par jour pour leur état de santé général du jour −1 jusqu'au jour 12 après la vaccination et une fois par jour pour des signes cliniques associés avec l'infection du jour 13 au jour 24 après l'infection. Le gain moyen quotidien (GMQ) et les résultats des analyses sérologiques et de virémie ont été évalués dans les expériences 1 et 2. Les pointages de lésions pulmonaires et les résultats de détection du VSRRP dans le tissu pulmonaire ont été évalués dans l'expérience 2. Dans l'expérience 1, le vaccin s'est montré sécuritaire étant donné qu'il n'y avait aucune différence significative entre les porcelets vaccinés et les porcelets ayant reçu un placebo. Dans l'expérience 2, l'efficacité du vaccin, avec un DDI de 14 j après la vaccination, a été établie, étant donné que les porcelets vaccinés, et soumis à une infection défi avaient des valeurs significativement moins élevées de pointage de lésions pulmonaires, de virémie, de charge virale dans le tissu pulmonaire, et des pointages de signes cliniques totaux, avec un GMQ significativement plus élevé, comparativement au porcs vaccinés avec un placebo et soumis à une infection défi.(Traduit par Docteur Serge Messier).

Safety and efficacy of a novel European vaccine for porcine reproductive and respiratory virus in bred gilts.

Porcine reproductive and respiratory syndrome virus (PRRSV) can be devastating to commercial breeding operations. The objective of this study was to evaluate a novel European PRRSV vaccinal strain for safety and efficacy in bred gilts. In 2 experiments, 110 gilts were vaccinated intramuscularly and the vaccine was evaluated for safety and efficacy. Gilts in Experiment 1 were evaluated for local and systemic reactions and gilts in both experiments were observed for clinical signs of disease through farrow. In both experiments, piglet clinical observations, piglet average daily weight gain (ADWG), gilt serology [determined by enzyme-linked immunosorbent assay (ELISA)], gilt and piglet viremia [determined by quantitative real-time polymerase chain reaction (qPCR)], as well as piglet lung lesion scores and PRRS virus in lung tissue (qPCR) were determined. The vaccine was shown to be safe as there were no significant differences among groups in either experiment. Efficacy was established in Experiment 2 as both vaccinated groups were associated with desirable significant differences in percentage of gilts with abnormal clinical findings; gilt viral load post-challenge [day 125, day of farrowing (DOF), and DOF + 13]; percentages of alive, healthy live, weak live, and mummified piglets per litter at farrowing and weaning; percentage of piglets per gilt that were positive for viremia; percentage of piglets per gilt with clinical disease; and piglet viral load on DOF. It was concluded that a vaccine formulated from the PRRSV modified live virus (MLV) strain 94881 is a safe and effective method of protection against the detrimental effects of virulent PRRSV infection in breeding female pigs.

Le virus du syndrome reproducteur et respiratoire porcin (VSRRP) peut être dévastateur pour les opérations de reproduction commerciales. L'objectif de la présente étude était d'évaluer l'innocuité et l'efficacité d'une nouvelle souche vaccinale européenne du VSRRP chez des cochettes saillies. Lors de deux expériences, 110 cochettes ont été vaccinées par voie intramusculaire afin d'évaluer l'innocuité et l'efficacité du vaccin. Les cochettes de l'Expérience 1 ont été évaluées pour la présence de réactions locales et systémiques et les cochettes dans les deux expériences ont été observées pour vérifier la présence de signes cliniques de maladie jusqu'au moment de la mise-bas. Lors des deux expériences on nota les observations cliniques des porcelets, le gain de poids quotidien moyen des porcelets (GMQ), les titres sérologiques des truies [déterminés par épreuve immuno-enzymatique (ELISA)], la virémie chez les cochettes et les porcelets [déterminées par réaction d'amplification en chaine par la polymérase quantitative (qACP)], ainsi que par les pointages de lésions pulmonaires des porcelets et la quantité de virus SRRP dans le tissu pulmonaire (qACP). Le vaccin s'est avéré sécuritaire et il n'y avait pas de différence significative entre les groupes dans les deux expériences. L'efficacité a été établie lors de l'Expérience 2 alors que les deux groupes vaccinés ont été associés à des différences significatives souhaitées dans le pourcentage de cochettes avec des trouvailles cliniques anormales; dans la charge virale post-challenge par cochette [jour 125, jour de la mise-bas (JMB), et JMB + 13]; pourcentages de porcelets vivants, vivants en santé, vivants faibles, et momifiés par portée au moment de la mise-bas et au sevrage; pourcentages de porcelets par truie qui étaient positifs pour une virémie; pourcentage de porcelets par cochette avec une maladie clinique; et charge virale des porcelets au JMB. Il a été conclu qu'un vaccin formulé à partir de la souche 94881 du VSRRP vivant modifié est une méthode sécuritaire et efficace de protection contre les effets néfastes d'une infection par le VSRRP chez des porcs femelles de reproduction.(Traduit par Docteur Serge Messier).