Emergence of a New Lineage 1C Variant of PRRSV-2 in the United States

 

2021 Oct 18;8:752938. doi: 10.3389/fvets.2021.752938. eCollection 2021.

Emergence of a New Lineage 1C Variant of Porcine Reproductive and Respiratory Syndrome Virus 2 in the United States

Mariana Kikuti  ¹ , Igor A D Paploski  ¹ , Nakarin Pamornchainavakul  ¹ , Catalina Picasso-Risso  ¹ , Mark Schwartz  ^{1   2} , Paul Yeske  ³ , Brad Leuwerke  ³ , Laura Bruner  ³ , Deborah Murray  ⁴ , Brian D Roggow  ⁵ , Pete Thomas  ⁶ , Lori Feldmann  ⁷ , Matt Allerson  ⁸ , Melissa Hensch  ⁹ , Tyler Bauman  ⁹ , Brent Sexton  ⁹ , Albert Rovira  ¹ , Kimberly VanderWaal  ¹ , Cesar A Corzo  ¹

Abstract

We report an ongoing regional outbreak of an emerging porcine reproductive and respiratory syndrome virus (PRRSV2) variant within Lineage 1C affecting 154 breeding and grow-finishing sites in the Midwestern U.S. Transmission seemed to have occurred in two waves, with the first peak of weekly cases occurring between October and December 2020 and the second starting in April 2021. Most of cases occurred within a 120 km radius. Both orf5 and whole genome sequencing results suggest that this represents the emergence of a new variant within Lineage 1C distinct from what has been previously circulating. A case-control study was conducted with 50 cases (sites affected with the newly emerged variant) and 58 controls (sites affected with other PRRSV variants) between October and December 2020. Sites that had a market vehicle that was not exclusive to the production system had 0.04 times the odds of being a case than a control. A spatial cluster (81.42 km radius) with 1.68 times higher the number of cases than controls was found. The average finishing mortality within the first 4 weeks after detection was higher amongst cases (4.50%) than controls (0.01%). The transmission of a highly similar virus between different farms carrying on trough spring rises concerns for the next high transmission season of PRRS.

Keywords: disease outbreak; epidemics; epidemiology; porcine reproductive and respiratory disease virus; swine diseases.

Copyright © 2021 Kikuti, Paploski, Pamornchainavakul, Picasso-Risso, Schwartz, Yeske, Leuwerke, Bruner, Murray, Roggow, Thomas, Feldmann, Allerson, Hensch, Bauman, Sexton, Rovira, VanderWaal and Corzo.

Efficacy of a Modified-Live PRRSV-1 Vaccine Administered to 1-Day-Old Piglets

 Pathogens

. 2021 Oct 18;10(10):1342.

 doi: 10.3390/pathogens10101342.

Efficacy of a Modified Live Virus Vaccine against Porcine Reproductive and Respiratory Syndrome Virus 1 (PRRSV-1) Administered to 1-Day-Old Piglets in Front of Heterologous PRRSV-1 Challenge

Heinrich Kreutzmann 1, Sophie Dürlinger 1, Christian Knecht 1, Michaela Koch 1, Marta Cabana 2, Gerard Torrent 2, Mònica Balasch 2, Lucas P Taylor 3, Gyula Balka 4, Wilhelm Gerner 5 6, Andrea Ladinig 1

Affiliations 

• PMID: 34684293
 
• PMCID: PMC8537468
 
• DOI: 10.3390/pathogens10101342

Free PMC article

Abstract

PRRSV is one of the most important viruses in the global swine industry and is often controlled by the use of modified live virus (MLV) vaccines. This study assessed the impact of a PRRSV-1 MLV vaccine applied to 1-day-old piglets challenged on day 28 of life with a PRRSV-1 field isolate (AUT15-33). Twenty-one piglets were vaccinated within 24 h of birth (T02), whereas 20 piglets were left unvaccinated (T01). Necropsy was performed two weeks post-challenge. Comparing the two groups, T02 piglets showed significantly higher (p = 0.017) average daily weight gain. In addition, significantly lower (p < 0.0001) PRRSV RNA loads were measured in serum of T02 piglets at all investigated time points. All T01 piglets were viremic and shed virus in nasal swabs, whereas only 71.4% and 38.1% of the T02 group were viremic or shed virus, respectively. Piglets from T02 had significantly higher numbers (p < 0.0001) of IFN-γ producing lymphocytes compared to T01. At necropsy, differences in gross and histologic lung lesions were statistically significant (p = 0.012 and p < 0.0001, respectively) between the two groups. Hence, this MLV vaccine administered to 1-day-old piglets was able to protect piglets against PRRSV infection at weaning.

Keywords: 1-day-old pigs; AUT15-33; IFN-γ; MLV; PRRSV; cellular immune response; shedding; vaccination; viremia.

Conflict of interest statement

M.C., G.T., M.B. and L.P.T. are employees from the sponsor company. They were involved in the design of the study, in sample collection, analyses of data and in the decision to publish the results as indicated in the Author Contributions

 Vet Microbiol

. 2021 Sep 20;262:109240.

 doi: 10.1016/j.vetmic.2021.109240. Online ahead of print.

Disinfection and conditions associated with thermo-assisted drying and decontamination inconsistently produce negative PRRSV rRT-PCR results on metal surfaces

Rita Anne Neat 1, Zhang Jianqiang 2, Hai Hoang 3, Lauren McKeen 4, Christine L Mowrer 5, Derald J Holtkamp 6

Affiliations 

Affiliations

• 1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: ritaneat@iastate.edu.
• 2Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: jqzhang@iastate.edu.
• 3Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: hai.hoangthanh@hcmuaf.edu.vn.
• 4Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: lamckeen@iastate.edu.
• 5Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: clmowrer@iastate.edu.
• 6Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1800 Christensen Drive, Ames, IA, 50011, United States. Electronic address: holtkamp@iastate.edu.

• PMID: 34600200
 
• DOI: 10.1016/j.vetmic.2021.109240

Abstract

Because contaminated livestock trailers are a significant risk for transmitting viruses between herds, various methods of washing, disinfecting, and thermo-assisted drying and decontamination (TADD) have been evaluated for their effectiveness in inactivating porcine reproductive and respiratory syndrome virus (PRRSV) on contaminated surfaces. Information on when to expect negative qRT-PCR results after adequate trailer sanitation is lacking. The objective of this study was to evaluate whether there are conditions associated with washing-disinfectant-TADD procedures that will consistently produce a negative qRT-PCR result for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV on metal surfaces. 144 diamond plate aluminum coupons were spiked with PRRSV or phosphate-buffered saline (PBS) and treated with a designated disinfectant protocol. Disinfectants evaluated included multiple accelerated® hydrogen peroxide (AHP) disinfectants and a quaternary ammonium and glutaraldehyde combination disinfectant. Disinfectant was applied for 5 or 60 minutes of contact time at either 20 °C or -10 °C in a matrix of feces or PBS. All coupons were heated until the surface temperature of the coupon reached 71 °C and then held for 10 minutes to simulate TADD under field conditions. Post-treatment swabs for all treatment groups, except negative control groups, were positive by PRRSV qRT-PCR. Under the conditions evaluated in this study, consistently negative qRT-PCR results after treatments were not found. Therefore, for the purpose of monitoring compliance with trailer sanitation and decontamination protocols for PRRSV, alternatives to qRT-PCR should be explored.

Keywords: PCR; PRRSV; Swine; biosecurity.

Copyright © 2021 Elsevier B.V. All rights reserved.

 Transbound Emerg Dis

. 2021 Sep 23.

 doi: 10.1111/tbed.14327. Online ahead of print.

Description of changes of key performance indicators and PRRSV shedding over time in a naïve breeding herd following a PRRS MLV exposure

Giovani Trevisan 1, Clayton Johnson 2, Neil Benjamin 2, Laura Bradner 1, Daniel C L Linhares 1

Affiliations 

• PMID: 34553831
 
• DOI: 10.1111/tbed.14327

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is an important economic swine disease. The usage of PRRS modified live vaccines (MLV) is the predominant breeding herd immunologic solution used in the United States to minimize the economic losses associated with wild-type PRRS infection. Most of the current information on the effects of contemporary PRRS MLV vaccination on breeding herd performance under field conditions comes from herds with previous PRRSV exposure. Hence, there is little information on key performance indicators (KPI) changes after the exposure to a PRRS MLV in PRRSV-naïve breeding herds. The main objective of this longitudinal observational study was to describe selected KPI changes in a naïve breeding herd after PRRS MLV exposure. The secondary objective was to describe the pattern of detection of PRRSV RNA by RT-qPCR in processing fluid samples. There were transient increases for mummies during weeks 4-23 (+0.86%); increased pre-weaning mortality on weeks 3-5 (+3.76%); decrease in live born on weeks 4-5 (-0.46) leading to a decreased pig weaned/litter on weeks 5-10 (-0.69), and increased repeated services on weeks 3-23 (+5.53%). Transient changes observed after PRRS MLV exposures did not moved total pigs weaned to outside the control intervals. Starting on week 83 and for 53 consecutive weeks, there was no PRRSV detection in processing fluids, even though two whole-herd MLV exposures occurred within that period. This article is protected by copyright. All rights reserved.

Keywords: KPI; PRRSV MLV vaccine; naïve breeding herd; swine.

 Vet Microbiol

. 2021 Aug 12;261:109190.

 doi: 10.1016/j.vetmic.2021.109190.Online ahead of print.

Probability of PRRS virus detection in pooled processing fluid samples

Will A López 1, Phillip C Gauger 2, Karen M Harmon 2, Derald J Holtkamp 2, Jean Paul Cano 3, Nubia Macedo 2, Min Zhang 4, Gustavo S Silva 2, Jose Angulo 5, Jeffrey J Zimmerman 2, Daniel C L Linhares 6

Affiliations 

Affiliations

• 1Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; PIC North America, 100 Bluegrass Commons Blvd #2200, Hendersonville, TN 37075, United States.
• 2Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States.
• 3Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States; Pipestone Veterinary Services, 1300 US-75, Pipestone, MN 56164, United States.
• 4Department of Statistics, College of Liberal Arts and Sciences, Iowa State University, Ames, IA 50011, United States.
• 5Zoetis, Parsippany, NJ, United States.
• 6Veterinary Diagnostic and Production Animal Medicine Department, College of Veterinary Medicine, Iowa State University, Lloyd Veterinary Medical Center, 1809 S Riverside Dr., Ames, IA 50011-3619, United States. Electronic address: linhares@iastate.edu.

• PMID: 34411996
 
• DOI: 10.1016/j.vetmic.2021.109190

Abstract

There has been a tremendous increase in recent years of population-based diagnostic monitoring and surveillance strategies in swine populations. One example is the use of processing fluids (PF) to screen breeding herds for porcine reproductive and respiratory syndrome virus (PRRSV) activity. An important question from practitioners using such methods is on how intensively can the sample be pooled. More specifically, processing fluids of how many litters can be pooled into a single sample for diagnostic testing to preserve a high probability of PRRSV RNA detection at low prevalence situations? The objective of this study was to model the effect of pooling PF samples on the probability of PRRSV RNA detection. For this study, a PRRSV-positive PF field sample with a RT-rtPCR quantification cycle (Cq) value of 28 was selected to represent a litter of 11 pigs with a single viremic piglet. PF samples from a PRRSV-naïve herd were used to perform 6 replications of 8 two-fold serial dilutions of the PRRSV-positive sample, thus modeling the pooling effect (dilution). Each two-fold dilution represented an increase in the number of PRRS-negative pigs in the sample by a factor of 2. Samples were tested for PRRSV RNA by RT-rtPCR and the data was analyzed using linear and probit regression models. There was an average increment of 1.37 points in Ct for each two-fold dilution. The estimated probability of testing positive on RT-rtPCR was 43 %, 80 %, and 95 % when there was a single PRRSv-positive piglet among 784, 492, and 323 PRRSv-negative piglets contributing to the sample respectively. Results from this study support the practice of collecting and aggregating PF samples from multiple litters for PRRSV RNA testing.

Keywords: Monitoring; PRRS virus; Pooling; Processing fluids; Surveillance; Swine.

Copyright © 2021 Elsevier B.V. All rights reserved.