Using commercial ELISAs to assess humoral response in sows repeatedly vaccinated with MLV PRRSV.

Vet Rec. 2019 Oct 1. pii: vetrec-2019-105432. doi: 10.1136/vr.105432. [Epub ahead of print]

Using commercial ELISAs to assess humoral response in sows repeatedly vaccinated with modified live porcine reproductive and respiratory syndrome virus.

Díaz I1, Genís-Jorquera B2, Martín-Valls GE3, Mateu E2,3.

Author information

1

IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Bellaterra, Spain ivan.diaz@irta.es.

2

IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Bellaterra, Spain.

3

Departament de Sanitat i Anatomia Animals, Facultat Veterinària, Universitat Autònoma de Barcelona, Bellaterra, Spain.

Abstract

BACKGROUND: 

Sows in breeding herds are often mass vaccinated against porcine reproductive and respiratory syndrome (PRRS) every few months using modified live vaccines (MLV). Field veterinarians repeatedly report that multiple vaccinated sows test negative in ELISA. Obviously, this creates uncertainty when assessing the compliance of vaccination and the status of sows.

METHODS: 

In the present study, four commercial ELISAs were used to assess the serological PRRS status in gilts and sows of three farms that were PRRS MLV vaccinated every four months. Animals were tested before vaccination (BV) and postvaccination (PV). Total and neutralising antibodies and cell-mediated responses were also measured in animals that yielded negative results in all ELISAs.

RESULTS: 

The proportion of seronegative animals BV varied depending on the farm and the ELISA used. When samples were analysed using only one ELISA, a substantial number of negative results obtained BV remained as negative afterwards. Five animals were negative BV and PV with all the examined ELISAs. Those animals also yielded negative results in all the other immunological assays.

CONCLUSION: 

Our findings suggest that the use of ELISA for monitoring multiple PRRS MLV vaccinated sows is very limited due to the variability of the humoral responses and the moderate agreement between tests.

© British Veterinary Association 2019. No commercial re-use. See rights and permissions. Published by BMJ.

KEYWORDS: 

Diagnostics; ELISA; Porcine reproductive and respiratory syndrome (PRRS); Vaccines

PMID:

 

31575761

 

DOI:

 

10.1136/vr.105432

Machine-learning algorithms to identify key biosecurity practices and factors associated with breeding herds reporting PRRS outbreak

Author links open overlay panelGustavo S.Silvaa1GustavoMachadob1Kimberlee L.BakeraDerald J.HoltkampaDaniel C.L.Linharesa

a

Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States

b

Department of Population Health and Pathobiology, North Carolina State University, College of Veterinary Medicine, Raleigh, North Carolina, United States

Received 5 April 2019, Revised 12 August 2019, Accepted 19 August 2019, Available online 20 August 2019.

https://doi.org/10.1016/j.prevetmed.2019.104749Get rights and content

Abstract

Investments in biosecurity practices are made by producers to reduce the likelihood of introducing pathogens such as porcine reproductive and respiratory syndrome virus (PRRSv). The assessment of biosecurity practices in breeding herds is usually done through surveys. The objective of this study was to evaluate the use of machine-learning (ML) algorithms to identify key biosecurity practices and factors associated with breeding herds self-reporting (yes or no) a PRRS outbreak in the past 5 years. In addition, we explored the use of the positive predictive value (PPV) of these models as an indicator of risk for PRRSv introduction by comparing PPV and the frequency of PRRS outbreaks reported by the herds in the last 5 years. Data from a case control study that assessed biosecurity practices and factors using a survey in 84 breeding herds in U.S. from 14 production systems were used. Two methods were developed, method A identified 20 variables and accurately classified farms that had reported a PRRS outbreak in the previous 5 years 76% of the time. Method B identified six variables which 5 of these had already been selected by model A, although model B outperformed the former model with an accuracy of 80%. Selected variables were related to the frequency of risk events in the farm, swine density around the farm, farm characteristics, and operational connections to other farms. The PPVs for methods A and B were highly correlated to the frequency of PRRSv outbreaks reported by the farms in the last 5 years (Pearson r = 0.71 and 0.77, respectively). Our proposed methodology has the potential to facilitate producer’s and veterinarian’s decisions while enhancing biosecurity, benchmarking key biosecurity practices and factors, identifying sites at relatively higher risk of PRRSv introduction to better manage the risk of pathogen introduction.

Keywords

biosecurity practices and factors

PRRSv outbreaks

risk index

machine learning

decision-making

Processing fluids for longitudinal monitoring of PRRSV in herds undergoing virus elimination

Porcine Health Manag. 2019 Aug 1;5:18. doi: 10.1186/s40813-019-0125-x. eCollection 2019.

Use of processing fluid samples for longitudinal monitoring of PRRS virus in herds undergoing virus elimination.

Trevisan G1, Jablonski E2, Angulo J2, Lopez WA1, Linhares DCL1.

Author information

1

1Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, Iowa USA.

2

2Zoetis, Parsippany, New Jersey USA.

Abstract

This was an observational study that prospectively followed 29 breeding herds for 65 weeks in the U.S.A. that became infected with porcine reproductive and respiratory syndrome virus (PRRSv). The herds operated in a four-week batch farrowing system and adopted a load-close-expose strategy using a modified-live virus vaccine to achieve PRRSv stability. The purpose of this study was to describe time to stability (TTS) based on RT-qPCR testing for PRRSv RNA on processing fluid samples in herds undergoing PRRSv elimination, after implementing herd closure and mass exposure to a PRRS modified-live virus (MLV) vaccine. For the purpose of this study, stability was defined as consistently producing PRRSv-negative pigs. Study herds were monitored until two consecutive piglet batches tested PRRSv RT-qPCR negative, then 30 due-to-wean piglet sera from the second batch were tested for PRRSv RNA by RT-qPCR. Once the farm re-opened, sera from incoming naïve gilts were tested for anti-PRRSv antibodies by ELISA at 30- and 60-days post-entry to confirm negative status to PRRSv. Day zero was the day of whole-herd exposure to a commercial PRRS vaccine virus. Twenty-eight of 29 herds (96.55%) achieved TTS within the study period. TTS ranged from 18 to 55 weeks with a median of 27 weeks. Serum from due-to-wean piglets was collected on 28 farms, of which 26 (92.85%) obtained PRRSv RT-qPCR-negative results on the first collection. At the end of the observational period, 16 sow farms successfully re-introduced PRRSv-naïve gilts with no detected serologic response. In conclusion, the median time to achieve TTS in breeding herds being operated in a four-week batch farrowing system undergoing PRRSv elimination using load-close-expose with attenuated virus vaccine was 27 weeks. Also, processing fluid-based monitoring of breeding herds under PRRS elimination was practical and reliable to assess PRRSv stability.

KEYWORDS: 

Herd closure; Porcine reproductive and respiratory syndrome virus; Processing fluid; Time to stability

PMID:

 

31388438

 

PMCID:

 

PMC6670174

 

DOI:

 

10.1186/s40813-019-0125-x

Free PMC Article

Aerosol Detection and Transmission of PRRSV: What Is the Evidence, and What Are the Knowledge Gaps?

Viruses. 2019 Aug 3;11(8). pii: E712. doi: 10.3390/v11080712.

Aerosol Detection and Transmission of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): What Is the Evidence, and What Are the Knowledge Gaps?

Arruda AG1, Tousignant S2, Sanhueza J3, Vilalta C3, Poljak Z4, Torremorell M3, Alonso C5, Corzo CA3.

Author information

Abstract

In human and veterinary medicine, there have been multiple reports of pathogens being airborne under experimental and field conditions, highlighting the importance of this transmission route. These studies shed light on different aspects related to airborne transmission such as the capability of pathogens becoming airborne, the ability of pathogens to remain infectious while airborne, the role played by environmental conditions in pathogen dissemination, and pathogen strain as an interfering factor in airborne transmission. Data showing that airborne pathogens originating from an infectious individual or population can infect susceptible hosts are scarce, especially under field conditions. Furthermore, even though disease outbreak investigations have generated important information identifying potential ports of entry of pathogens into populations, these investigations do not necessarily yield clear answers on mechanisms by which pathogens have been introduced into populations. In swine, the aerosol transmission route gained popularity during the late 1990's as suspicions of airborne transmission of porcine reproductive and respiratory syndrome virus (PRRSV) were growing. Several studies were conducted within the last 15 years contributing to the understanding of this transmission route; however, questions still remain. This paper reviews the current knowledge and identifies knowledge gaps related to PRRSV airborne transmission.

KEYWORDS: 

aerosol; airborne; porcine reproductive and respiratory syndrome; porcine reproductive and respiratory syndrome virus (PRRSV); transmission

PMID:

 

31382628

 

DOI:

 

10.3390/v11080712

Front Vet Sci. 2019 Jun 21;6:194. doi: 10.3389/fvets.2019.00194. eCollection 2019.

Individual or Common Good? Voluntary Data Sharing to Inform Disease Surveillance Systems in Food Animals.

Perez AM1, Linhares DCL2, Arruda AG3, VanderWaal K1, Machado G4, Vilalta C1, Sanhueza JM1, Torrison J1, Torremorell M1, Corzo CA1.

Author information

Abstract

Livestock producers have traditionally been reluctant to share information related to their business, including data on health status of their animals, which, sometimes, has impaired the ability to implement surveillance programs. However, during the last decade, swine producers in the United States (US) and other countries have voluntarily begun to share data for the control and elimination of specific infectious diseases, such as the porcine reproductive and respiratory syndrome virus (PRRSv). Those surveillance programs have played a pivotal role in bringing producers and veterinarians together for the benefit of the industry. Examples of situations in which producers have decided to voluntarily share data for extended periods of time to support applied research and, ultimately, disease control in the absence of a regulatory framework have rarely been documented in the peer-reviewed literature. Here, we provide evidence of a national program for voluntary sharing of disease status data that has helped the implementation of surveillance activities that, ultimately, allowed the generation of critically important scientific information to better support disease control activities. Altogether, this effort has supported, and is supporting, the design and implementation of prevention and control approaches for the most economically devastating swine disease affecting the US. The program, which has been voluntarily sustained and supported over an extended period of time by the swine industry in the absence of any regulatory framework and that includes data on approximately 50% of the sow population in the US, represents a unique example of a livestock industry self-organized surveillance program to generate scientific-driven solutions for emerging swine health issues in North America.

KEYWORDS: 

US; data sharing; epidemiology; porcine reproductive and respiratory syndrome; surveillance

PMID:

 

31294036

 

PMCID:

 

PMC6598744

 

DOI:

 

10.3389/fvets.2019.00194

Assessment of immediate production impact following attenuated PRRS type 2 virus vaccination in swine breeding herds

• Cesar A. A. Moura,
• Clayton Johnson,
• Samuel R. Baker,
• Derald J. Holtkamp,
• Chong Wang and
• Daniel C. L. LinharesEmail authorView ORCID ID profile

Porcine Health Management20195:13

https://doi.org/10.1186/s40813-019-0120-2

©  The Author(s). 2019

• Received: 6 February 2019
• Accepted: 13 May 2019
• Published: 11 June 2019

Abstract

Background

To mitigate production impact of porcine reproductive and respiratory syndrome (PRRS) virus outbreaks, it has been common to preventively vaccinate swine breeding herds using PRRS modified live virus (MLV) vaccine. However, attenuated PRRS virus (PRRSv) may result negative impact on farm productivity. The objective of this study was to measure the immediate impact of PRRS type 2 MLV vaccine on breeding herd performance under field conditions. Eight PRRS-stable farms routinely mass vaccinating females with commercial PRRS MLV vaccines were enrolled on study. Vaccination dates were collected and weekly changes in abortions, neonatal losses, pre-weaning mortality, pigs weaned per sow, and wean-to-first-service interval were assessed for up to 6 weeks after each vaccination. A 6-week period prior to each vaccination was established as baseline. Statistical process control (SPC) analysis was conducted to detect significant productivity decreases after MLV interventions, on each farm, and a mixed regression model was used, at the aggregated data level, to assess the productivity change 6 weeks after PRRS MLV vaccinations, compared to baseline.

Results

Out of 65 herd-MLV vaccinations, SPC analysis detected increase on abortions 4 times (6.1%), on neonatal losses 7 times (10.7%), on pre-weaning mortality 2 times (3%), on wean-to-first-service interval 2 times (3%), and no change in total pigs weaned. On aggregated data analysis, there was no significant change in abortion rate, neonatal losses, number of pigs weaned per sow, and wean-to-first-service interval. However, there was an increase of 0.26% of pre-weaning mortality 2 weeks after vaccination compared to the baseline.

Conclusions

Under study conditions, individual PRRS-stable sow farms had experienced transient, and numerically small changes in productivity following PRRS type 2 MLV vaccination. There was a small increase of pre-weaning mortality 2 weeks after vaccination, but no evidence of significant production impact at aggregated data analysis for abortion rate, neonatal losses, pigs weaned per sow and wean-to-first-service interval.

Keywords

• Swine
• PRRS
• Vaccination
• MLV
• Outbreak
• Epidemiology

Automated clustering approach applied to surveillance of PRRSV field strains.

Infect Genet Evol. 2019 Apr 27. pii: S1567-1348(18)30899-2. doi: 10.1016/j.meegid.2019.04.014. [Epub ahead of print]

Evaluating an automated clustering approach in a perspective of ongoing surveillance of porcine reproductive and respiratory syndrome virus (PRRSV) field strains.

Lambert MÈ1, Arsenault J2, Audet P3, Delisle B4, D'Allaire S5.

Author information

1

Laboratoire d'épidémiologie et de médecine porcine (LEMP), Faculty of Veterinary Medicine, Université de Montréal, St. Hyacinthe, Quebec, Canada. Electronic address: marie-eve.lambert@umontreal.ca.

2

Swine and Poultry Infectious Diseases Research Center (CRIPA), Faculty of Veterinary Medicine, Université de Montréal, St. Hyacinthe, Quebec, Canada. Electronic address: julie.arsenault@umontreal.ca.

3

Laboratoire d'épidémiologie et de médecine porcine (LEMP), Faculty of Veterinary Medicine, Université de Montréal, St. Hyacinthe, Quebec, Canada. Electronic address: pascal.audet@umontreal.ca.

4

Laboratoire d'épidémiologie et de médecine porcine (LEMP), Faculty of Veterinary Medicine, Université de Montréal, St. Hyacinthe, Quebec, Canada. Electronic address: benjamin.delisle@umontreal.ca.

5

Laboratoire d'épidémiologie et de médecine porcine (LEMP), Faculty of Veterinary Medicine, Université de Montréal, St. Hyacinthe, Quebec, Canada. Electronic address: sylvie.dallaire@umontreal.ca.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) has a major economic impact on the swine industry. The important genetic diversity needs to be considered for disease management. In this regard, information on the circulating endemic strains and their dispersal patterns through ongoing surveillance is beneficial. The objective of this project was to classify Quebec PRRSV ORF5 sequences in genetic clusters and evaluate stability of clustering results over a three-year period using an in-house automated clustering system. Phylogeny based on maximum likelihood (ML) was first inferred on 3661 sequences collected in 1998-2013 (Run 1). Then, sequences collected between January 2014 and September 2016 were sequentially added into 11 consecutive runs, each one covering a three-month period. For each run, detection of clusters, which were defined as groups of ≥15 sequences having a ≥ 70% rapid bootstrap support (RBS) value, was automated in Python. Cluster stability was described for each cluster and run based on the number of sequences, RBS value, maximum pairwise distance and agreement in sequence assignment to a specific cluster. First and last run identified 29 and 33 clusters, respectively. In the last run, about 77% of the sequences were classified by the system. Most clusters were stable through time, with sequences attributed to one cluster in Run 1 stayed in the same cluster for the 11 remaining runs. However, some initial groups were further subdivided into subgroups with time, which is important for monitoring since one specific wild-type cluster increased from 0% in 2007 to 45% of all sequences in 2016. This automated classification system will be integrated into ongoing surveillance activities, to facilitate communication and decision-making for stakeholders of the swine industry.

Copyright © 2019. Published by Elsevier B.V.

KEYWORDS: 

Classification; ORF5; PRRS; Phylogeny; Surveillance

PMID:

 

31039449

 

DOI:

 

10.1016/j.meegid.2019.04.014