Friday, April 29, 2016

Concurrent vaccination of pigs with type 1 and type 2 PRRSV protected against type 1 but not against type 2 PRRSV

 2015 Dec;103:193-200. doi: 10.1016/j.rvsc.2015.10.011. Epub 2015 Oct 28.

Concurrent vaccination of pigs with type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) protects against type 1 PRRSV but not against type 2 PRRSV on dually challenged pigs.

Abstract

The objective of the present study was to evaluate the effect of concurrent vaccination of pigs with both type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against heterologous dual challenge of both genotypes and compare with single vaccination of pigs against heterologous single challenge of both genotypes. Pigs were administered both type 1 and type 2 PRRSV vaccine concurrently into separate anatomical sites at 28 days of age and inoculated intranasally with both genotypes at 63 days of age. Neutralizing antibodies (NA) were not detected in any pigs in any group (NA titer <2 log2) throughout the experiment. In addition, concurrent vaccination of pigs with two PRRSV genotypes had significantly lower numbers of type 1 and type 2 PRRSV-specific interferon-γ secreting cells (IFN-γ-SC) compared to vaccination of pigs with type 1 or type 2 PRRSV only. Despite the decreased induction of type 1 PRRSV-specific IFN-γ-SC, concurrent vaccination is still able to reduce type 1 PRRSV viremia whereas the decreased induction of type 2 PRRSV-specific IFN-γ-SC by concurrent vaccination correlates with lack of reduction of type 2 PRRSV viremia after dual challenge. The results of this study demonstrated that concurrent vaccination of pigs with two PRRSV genotypes is able to reduce the levels of type 1 PRRSV viremia and lung lesions but not able to reduce the levels of type 2 PRRSV viremia and lung lesions.
Copyright © 2015 Elsevier Ltd. All rights reserved.

KEYWORDS: 

Concurrent vaccination; Interference; Porcine reproductive and respiratory syndrome virus; Porcine reproductive and respiratory syndrome virus vaccine
PMID:
 
26679817
 
[PubMed - in process]

Spatial and temporal dynamics of PRRS in Denmark from 2007 to 2010

 2015 Dec 21;11:303. doi: 10.1186/s12917-015-0617-0.

Spatial analysis and temporal trends of porcine reproductive and respiratory syndrome in Denmark from 2007 to 2010 based on laboratory submission data.

Abstract

BACKGROUND: 

Porcine reproductive and respiratory syndrome (PRRS) has been a cause for great concern to the Danish pig industry since it was first diagnosed in 1992. The causative agent of PRRS is an RNA virus which is divided into different genotypes. The clinical signs, as well as its morbidity and mortality, is highly variable between herds and regions. Two different genotypes of PRRS virus (PRRSV) are found in Denmark: type 1 and type 2. Approximately 40% of Danish swine herds are seropositive for one or both PRRSV types. The objective of this study was to describe the temporal trend and spatial distribution of PRRSV in Danish swine herds from 2007 to 2010, based on type-specific serological tests from the PRRSsurveillance and control program in Denmark using the results stored in the information management system at the National Veterinary Institute, Technical University of Denmark (DTU Vet).

RESULTS: 

The average monthly seroprevalence of PRRSV type 1 was 9% (minimum of 5%; maximum of 13%) in breeding herds, and 20% (minimum of 14%; maximum of 26%) in production herds; PRRSV type 2 had an average seroprevalence of 3% (minimum of 1%; maximum of 9%) in breeding herds and of 9% (minimum of 5%; maximum of 13%) within production herds. The seroconversion rate followed a similar and consistent pattern, being higher for type 1 than for type 2 for both PRRSV types. Regarding the spatiotemporal results, the relative risk distribution maps changed over time as a consequence of the changes in PRRSV seroprevalence, suggesting a general decline in the extent of areas with higher relative risk for both type 1 and 2. Local spatial analysis results demonstrated the existence of statistically significant clusters in areas where the relative risk was higher for both herds.

CONCLUSIONS: 

PRRSV type 1 seroprevalence was constantly higher than for PRRSV type 2 in both herd types. Significant spatial clusters were consistently found in Denmark, suggesting that PRRSV is endemic in these areas. Furthermore, relative risk distribution maps revealed different patterns over time as a consequence of the changes in seroprevalence.
PMID:
 
26689831
 
[PubMed - in process] 
PMCID:
 
PMC4687366

Efficacy of Fostera PRRS vaccine against a virulent field strain

 2016 Jan;80(1):1-11.

Efficacy of Fostera PRRS modified live virus vaccine against a Canadian heterologous virulent field strain of porcine reproductive and respiratory syndrome virus.

Abstract

Vaccination is a useful option to control infection with porcine reproductive and respiratory syndrome virus (PRRSV), and several modified live-PRRSV vaccines have been developed. These vaccines have shown some efficacy in reducing the incidence and severity of clinical disease as well as the duration of viremia and virus shedding but have failed to provide sterilizing immunity. The efficacy of modified live-virus (MLV) vaccines is greater against a homologous strain compared with heterologous PRRSV strains. The objective of this study was to evaluate the efficacy of Fostera PRRS MLV vaccine in protecting against challenge with a heterologous field strain widely circulating in the swine herds of eastern Canada. Forty-six piglets were divided into 4 groups: nonvaccinated-nonchallenged; nonvaccinated-challenged; vaccinated-challenged; and vaccinated-nonchallenged. The animals were vaccinated at 23 d of age with Fostera PRRS and challenged 23 d later with a heterologous field strain of PRRSV (FMV12-1425619). Overall, the vaccine showed some beneficial effects in the challenged animals by reducing the severity of clinical signs and the viral load. A significant difference between nonvaccinated and vaccinated animals was detected for some parameters starting 11 to 13 d after challenge, which suggested that the cell-mediated immune response or other delayed responses could be more important than pre-existing PRRSV antibodies in vaccinated animals within the context of protection against heterologous strains. 
PMID:
 
26732457
 
[PubMed - in process] 
PMCID:
 
PMC4686029
 [Available on 2016-07-01]

Thursday, April 28, 2016

Progress on the PRRS regional control project in Minnesota

 2016 Feb 19;11(2):e0149498. doi: 10.1371/journal.pone.0149498. eCollection 2016.

Measuring Progress on the Control of Porcine Reproductive and Respiratory Syndrome (PRRS) at a Regional Level: The Minnesota N212 Regional Control Project (Rcp) as a Working Example.

Abstract

Due to the highly transmissible nature of porcine reproductive and respiratory syndrome (PRRS), implementation of regional programs to control the disease may be critical. Because PRRS is not reported in the US, numerous voluntary regional control projects (RCPs) have been established. However, the effect of RCPs on PRRS control has not been assessed yet. This study aims to quantify the extent to which RCPs contribute to PRRScontrol by proposing a methodological framework to evaluate the progress of RCPs. Information collected between July 2012 and June 2015 from the Minnesota Voluntary Regional PRRS Elimination Project (RCP-N212) was used. Demography of premises (e.g. composition of farms with sows = SS and without sows = NSS) was assessed by a repeated analysis of variance. By using general linear mixed-effects models, active participation of farms enrolled in the RCP-N212, defined as the decision to share (or not to share) PRRS status, was evaluated and used as a predictor, along with other variables, to assess the PRRS trend over time. Additionally, spatial and temporal patterns of farmers' participation and the disease dynamics were investigated. The number of farms enrolled in RCP-N212 and its geographical coverage increased, but the proportion of SS and NSS did not vary significantly over time. A significant increasing (p<0.001) trend in farmers' decision to share PRRS status was observed, but with NSS producers less willing to report and a large variability between counties. The incidence of PRRS significantly (p<0.001) decreased, showing a negative correlation between degree of participation and occurrence of PRRS (p<0.001) and a positive correlation with farm density at the county level (p = 0.02). Despite a noted decrease in PRRS, significant spatio-temporal patterns of incidence of the disease over 3-weeks and 3-kms during the entire study period were identified. This study established a systematic approach to quantify the effect of RCPs on PRRS control. Despite an increase in number of farms enrolled in the RCP-N212, active participation is not ensured. By evaluating the effect of participation on the occurrence of PRRS, the value of sharing information among producers may be demonstrated, in turn justifying the existence of RCPs.

PMID: 
26895148    
[PubMed - in process] 
PMCID: 
PMC4760934

Financial Impacts of Swine Diseases in Vietnam

 2016 Feb 29. doi: 10.1111/tbed.12482. [Epub ahead of print]

Financial Impacts of Priority Swine Diseases to Pig Farmers in Red River and Mekong River Delta, Vietnam.

Abstract

A study was conducted between May 2013 and August 2014 in three provinces of Vietnam to investigate financial impacts of swine diseases in pig holdings in 2010-2013. The aim of the study was to quantify the costs of swine diseases at producer level in order to understand swine disease priority for monitoring at local level. Financial impacts of porcine reproductive and respiratory syndrome (PRRS), foot and mouth disease (FMD), and epidemic diarrhoea were assessed for 162 pig holders in two Red River Delta provinces and in one Mekong River Delta province, using data on pig production and swine disease outbreaks at farms. Losses incurred by swine diseases were estimated, including direct losses due to mortality (100% market value of pig before disease onset) and morbidity (abortion, delay of finishing stage), and indirect losses due to control costs (treatment, improving biosecurity and emergency vaccination) and revenue foregone (lower price in case of emergency selling). Financial impacts of swine diseases were expressed as percentage of gross margin of pig holding. The gross margin varied between pig farming groups (P < 0.0001) in the following order: large farm (USD 18 846), fattening farm (USD 7014) and smallholder (USD 2350). The losses per pig holding due to PRRS were the highest: 41% of gross margin for large farm, 38% for fattening farm and 63% for smallholder. Cost incurred by FMD was lower with 19%, 25% and 32% of gross margin of pig holding in large farm, fattening farm and smallholder, respectively. The cost of epidemic diarrhoea was the lowest compared to losses due to PRRS and FMD and accounted for around 10% of gross margin of pig holding in the three pig farming groups. These estimates provided critical elements on swine disease priorities to better inform surveillance and control at both national and local level.
© 2016 Blackwell Verlag GmbH.

KEYWORDS: 

Vietnam; financial impact; gross margin; pig holdings; swine disease
PMID:
 
26924683
 
[PubMed - as supplied by publisher]

Efficacy of commercial type I PRRSv vaccine against a type II isolate

 2016 Apr;172:43-9. doi: 10.1016/j.vetimm.2016.02.016. Epub 2016 Feb 27.

Efficacy of commercial genotype 1 porcine reproductive and respiratory syndrome virus (PRRSV) vaccine against field isolate of genotype 2 PRRSV.

Abstract

Although several recent studies have found that type 1 porcine reproductive and respiratory syndrome virus (PRRSV) modified live virus (MLV) vaccine showed appreciable levels of cross-protection against type 2 PRRSV infection, the possibility of cross-protection between two genotype of PRRSV is still controversial. To determine potential protective efficacy against hetero-genotype field strain of PRRSV and to improve understandings of the mechanisms underlying performance improvement after infection in vaccinated animals, piglets were vaccinated with type 1 PRRSV MLV vaccine and challenged with type 2 field strain of PRRSV. As a result, vaccinated animals gained on average 8.45kg in comparison to 4.77kg measured in non-vaccinated animals during a 3-week period after viral challenge, which shows using a certain PRRSV vaccine could be clinically effective against heterologous genotypic virus challenge. In vaccinated animals, viremia was reduced and cleared rapidly, whilst viral load was much higher and reduced more slowly, indicating rebound viremia in non-vaccinated animals. The titers of neutralizing antibody against the type 2 PRRSV did not exceed the protective level in any animal from both vaccinated and control groups. Instead, antibody avidity of vaccinated animals was much higher than in the control group clearly. Furthermore, a strong negative correlation between antibody avidity and viremia was noted in 80% of vaccinated animals. Through those results from tests evaluating degree of antibody maturation and its relevance with clearing viremia, it could be suggested that non-neutralizing antibodies induced by vaccination prior to challenge might play a key role in protection against PRRSV infection, especially in early time course. 
Copyright © 2016 Elsevier B.V. All rights reserved.

KEYWORDS: 

Avidity; Challenge; Immunity; Porcine reproductive and respiratory syndrome virus; Vaccine

The effect of PRRSv and PEDv challenge on growing pigs II: Intestinal integrity and function

 2016 Feb;94(2):523-32. doi: 10.2527/jas.2015-9836.

The effect of porcine reproductive and respiratory syndrome virus and porcine epidemic diarrhea virus challenge on growing pigs II: Intestinal integrity and function.

Abstract

The objective of this study was to determine if intestinal function and integrity is altered due to porcine reproductive and respiratory syndrome (PRRS) virus and porcine epidemic diarrhea (PED) virus infection in growing pigs. Forty-two gilts (16.8 ± 0.6 kg BW), naïve for PRRS and PED, were selected and randomly assigned to 1 of 4 treatments: 1) a control (CON; = 6), 2) PRRS virus challenge only (PRRS; = 12), 3) PED virus challenge only (; = 12), or 4) coinfection of PRRS + PED viruses (PRP; = 12). Treatments 2 and 4 were inoculated with a live field strain of PRRS virus on d 0 after inoculation. Treatments 3 and 4 were inoculated with PED virus on 14 d after inoculation (dpi) and all pigs were euthanized 7 d later (21 dpi). Infection with PRRS virus was determined by viremia and seroconversion. Fecal quantitative PCR was used to confirm PED virus infection. Control pigs remained PRRS and PED virus negative throughout the study. Compared with the CON, intestinal morphology was unaffected by PRRS. As expected, PED and PRP treatments resulted in duodenum, jejunum, and ileum villus atrophy compared with the CON treatment ( < 0.01). Ex vivo transepithelial electrical resistance (TER) did not differ between CON and PRRS pigs (P < 0.05) but was reduced by 40% in PED alone ( < 0.01). Interestingly, TER was increased ( < 0.01) in the PRP pigs. Active transport of glucose was increased in PRRS pigs over CON pigs ( < 0.01), whereas PED had pigs increased ( < 0.01) active glutamine transport over the CON pigs. Jejunum GLUT2 mRNA abundance and sucrase, maltase, and Na+/K+ adenosine triphosphatase activities tended to be increased in PRRS pigs compared with CON pigs ( < 0.06). The jejunum AA transporter, SLC6A14, and mucin 2 mRNA abundance tended to be increased in PED-only pigs ( < 0.10). These data suggest that PRRS infection supports a higher affinity for glucose uptake, whereas PED favors glutamine uptake. Interestingly, digestive machinery during PED challenge remained intact. Altogether, PED but not PRRS challenges alter intestinal morphology and integrity in growing pigs. 
PMID:
 
27065122
 
[PubMed - in process]