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Sunday, June 2, 2013

Comparative pathogenesis of European North American genotypes PRRSv in infected boar


Abstract

BACKGROUND:

Porcine reproductive and respiratory syndrome virus (PRRSV) now has two main genotypes, genotype 1 (European) and genotype 2 (North American). There is a lack of data on the comparison of pathogenicity of the two genotypes in boars. The objectives of the present study were to evaluate the amount of PRRSV present in semen over time and compare the viral distribution and microscopic lesions of type 1 and type 2 PRRSV-infected boars.

METHODS:

Twenty-four 8-month-old PRRSV-naive Duroc boars were randomly allocated to 3 treatment groups. The boars in groups 1 (n = 9) and 2 (n = 9) were intranasally inoculated with type 1 or type 2 PRRSV, respectively. The boars in groups 1 (n = 6) served as negative controls. Semen and blood samples were collected up to 35 days post-inoculation (dpi), and necropsies were performed on 14, 21, and 35 dpi.

RESULTS:

There were no significant differences in the genomic copy number of PRRSV, microscopic testicular lesion score, number of PRRSV-positive germ cells, or number of apoptotic cells between the type 1 and type 2 PRRSV-infected boars throughout the experiment. Histopathological changes were manifested by the desquamation of spermatocytes and the presence of multinucleated giant cells in seminiferous tubules of both type 1 and type 2 PRRSV-infected boars. The distribution of PRRSV-positive cells was focal; the virus was found in single germ cells or small clusters of germ cells, localized to the spermatogonia, spermatocytes, spermatids, and non-sperm cells in type 1 and type 2 PRRSV-infected boars.

CONCLUSIONS:

The results of this study demonstrated that two genotypes of PRRSV do not have significantly different virulence toward the male reproductive system of pigs.
PMID:
 
23687995
 
[PubMed - as supplied by publisher] 
PMCID:
 
PMC3663669



Han K, Seo H W, Park C, Oh Y, Kang I, Chae C. Comparative pathogenesis of type 1 (European genotype) and type 2 (North American genotype) porcine reproductive and respiratory syndrome virus in infected boar. Virology journal 2013;10(1):156-156.

Friday, April 5, 2013

Kinetics of the PRRSv humoral immune response in swine serum and oral fluids collected from boars

Abstract

BACKGROUND:

The object of this study was to describe and contrast the kinetics of the humoral response in serum and oral fluid specimens during acute porcine reproductive and respiratory syndrome virus (PRRSV) infection. The study involved three trials of 24 boars each. Boars were intramuscularly inoculated with a commercial modified live virus (MLV) vaccine (Trial 1), a Type 1 PRRSV field isolated (Trial 2), or a Type 2 PRRSV field isolate (Trial 3). Oral fluid samples were collected from individual boars on day post inoculation (DPI) -7 and 0 to 21. Serum samples were collected from all boars on DPI -7, 0, 7, 14, 21 and from 4 randomly selected boars on DPI 3, 5, 10, and 17. Thereafter, serum and oral fluid were assayed for PRRSV antibody using antibody isotype-specific ELISAs (IgM, IgA, IgG) adapted to serum or oral fluid.

RESULTS:

Statistically significant differences in viral replication and antibody responses were observed among the three trials in both serum and oral fluid specimens. PRRSV serum IgM, IgA, and IgG were first detected in samples collected on DPI 7, 10, and 10, respectively. Oral fluid IgM, IgA, and IgG were detected in samples collected between DPI 3 to 10, 7 to 10, and 8 to 14, respectively.

CONCLUSIONS:

This study enhanced our knowledge of the PRRSV humoral immune response and provided a broader foundation for the development and application of oral fluid antibody-based diagnostics.

PMID:
 
23537175
 
[PubMed - as supplied by publisher]



Kittawornrat A, Engle M, Panyasing Y, Olsen C, Schwartz K, Rice A, Lizano S, Wang C, Zimmerman J. Kinetics of the porcine reproductive and respiratory syndrome virus (PRRSV) humoral immune response in swine serum and oral fluids collected from individual boars. BMC veterinary research 2013;9(1):61-61.

Monday, April 1, 2013

Probability of detecting PRRSv infection using pen-based swine oral fluid specimens as a function of within-pen prevalence


Abstract

Pen-based oral fluid sampling has proven to be an efficient method for surveillance of infectious diseases in swine populations. To better interpret diagnostic results, the performance of oral fluid assays (antibody- and nucleic acid-based) must be established for pen-based oral fluid samples. Therefore, the objective of the current study was to determine the probability of detecting Porcine reproductive and respiratory syndrome virus (PRRSV) infection in pen-based oral fluid samples from pens of known PRRSV prevalence. In 1 commercial swine barn, 25 pens were assigned to 1 of 5 levels of PRRSV prevalence (0%, 4%, 12%, 20%, or 36%) by placing a fixed number (0, 1, 3, 5, or 9) of PRRSV-positive pigs (14 days post PRRSV modified live virus vaccination) in each pen. Prior to placement of the vaccinated pigs, 1 oral fluid sample was collected from each pen. Thereafter, 5 oral fluid samples were collected from each pen, for a total of 150 samples. To confirm individual pig PRRSV status, serum samples from the PRRSV-negative pigs (n = 535) and the PRRSV vaccinated pigs (n = 90) were tested for PRRSV antibodies and PRRSV RNA. The 150 pen-based oral fluid samples were assayed for PRRSV antibody and PRRSV RNA at 6 laboratories. Among the 100 samples from pens containing ≥1 positive pig (≥4% prevalence) and tested at the 6 laboratories, the mean positivity was 62% for PRRSV RNA and 61% for PRRSV antibody. These results support the use of pen-based oral fluid sampling for PRRSV surveillance in commercial pig populations.
PMID:
 
23536612
 
[PubMed - as supplied by publisher]


Olsen C, Wang C, Christopher Hennings J, Doolittle K, Harmon K M, Abate S, Kittawornrat A, Lizano S, Main R, Nelson E A, Otterson T, Panyasing Y, Rademacher C, Rauh R, Shah R, Zimmerman J. Probability of detecting Porcine reproductive and respiratory syndrome virus infection using pen-based swine oral fluid specimens as a function of within-pen prevalence. Journal of veterinary diagnostic investigation 2013 [in press].



Molecular evolution of PRRSV in Europe: Current state of play


Molecular evolution of PRRSV in Europe: Current state of play.

Source

Department of Pathology and Veterinary Diagnostics, Faculty of Veterinary Medicine, Warsaw University of Life Sciences - SGGW, Nowoursynowska 159c, 02-776 Warsaw, Poland. Electronic address: tomasz_stadejek@sggw.pl.

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major threat to European swine production. The existence of extensive genetic variation in endemic strains and the presence of highly virulent strains in other geographic regions pose the threat of devastating epidemic outbreaks. Here we describe the current knowledge of genetic variation in European PRRSV isolates, the implications for PRRSV evolution, and the presence of multiple genetic lineages of Type 2 (North American genotype) isolates in Europe. In Type 1 (European genotype) PRRSV, three genetic subtypes are recognized and a fourth subtype appears to be present. Type 2 PRRSV was considered to be genetically homogenous in Europe due to a unique presence of an introduced vaccine strain, but independent introductions of virulent Type 2 field viruses are now evident. In Type 1 PRRSV, only subtype 1 (Lelystad virus-like) circulates in Central and Western Europe and globally. In Eastern Europe, all subtypes are present. The subtypes of Type 1 PRRSV also exhibit length differences in the nucleocapsid protein, ranging in size from 124 to 132 amino acids depending on subtype. This size heterogeneity is unparalleled in the nucleocapsid proteins of Type 2 PRRSV or other viruses. Surprisingly, it affects the C-terminus, otherwise thought to be under strong structural constraints. Finally, divergent subtypes of Type 1 PRRSV have produced high rates of false-negative RT-PCR results in diagnostic tests, and may also degrade the reliability of serodiagnostic assays using the nucleocapsid protein antigen. In summary, the extensive genetic diversity of Type 1 PRRSV is of relevance for understanding nucleocapsid protein structure/function relationships. Further, the extensive genetic diversity of Type 1 PRRSV in Europe, and the presence of diverse Type 2 PRRSV strains, together emphasize the importance of relevant validation of PRRSV diagnostics. More extensive and systematic molecular phylogeny studies are needed to fully understand PRRSV diversity in Europe, to provide swine producers with reliable diagnostics, and to better assess the potential consequences of endemic spread and exotic introductions.
Copyright © 2013 Elsevier B.V. All rights reserved.
PMID:
 
23528651
 
[PubMed - as supplied by publisher]


Stadejek T, Stankevicius A, Murtaugh M P, Oleksiewicz M B. Molecular evolution of PRRSV in Europe: Current state of play. Veterinary microbiology 2013 [in press].

Tuesday, March 19, 2013

Effect of saliva stabilisers on detection of PRRSv in oral fluid by qPCR

Abstract

This study evaluated the effect of extraction-amplification methods, storage temperature and saliva stabilisers on detection of porcine reproductive and respiratory syndrome virus (PRRSV) RNA by quantitative reverse transcriptase real-time PCR (qRT-PCR) in porcine oral fluid. The diagnostic performance of different extraction-amplification methods was examined using a dilution series of oral fluid spiked with PRRSV. To determine RNA stability, porcine oral fluid, with or without commercially available saliva stabilisers, was spiked with PRRSV, stored at 4°C or room temperature and tested for the presence of PRRSV RNA by qRT-PCR. PRRSV RNA could be detected in oral fluid using all extraction-amplification combinations, but the limit of detection varied amongst different combinations. Storage temperature and saliva stabilisers had an effect on the stability of PRRSV RNA, which could only be detected for 7days when PRRSV spiked oral fluid was kept at 4°C or stabilised at room temperature with a commercial mRNA stabiliser.
Copyright © 2013 Elsevier Ltd. All rights reserved.

Decorte I, Van der Stede Y, Nauwynck H, De Regge N, Cay A B. Effect of saliva stabilisers on detection of porcine reproductive and respiratory syndrome virus in oral fluid by quantitative reverse transcriptase real-time PCR. The veterinary journal 2013 [in press].

In vitro inactivation of PRRSv and PRv by acidic electrolyzed water


Abstract

Slightly acidic electrolyzed water (SAEW, pH 5.0-6.5) is a novel disinfectant with environmentally friendly broad spectrum microbial decontamination properties which could have significant utility on farm. Two of the most important pathogenic viruses in pigs are porcine reproductive and respiratory syndrome virus (PRRSV) and pseudorabies virus (PRV). The aim of this study was to evaluate the viricidal effectiveness of SAEW against PRRSV and PRV in vitro under different available chlorine concentrations (ACCs, 30, 50 and 70mg/L), treatment times (5, 10 and 15min) and temperatures (4, 20, 40 and 60°C), respectively. SAEW had a strong viricidal activity against both PRRSV and PRV. This activity increased with increasing ACC, treatment time and temperature. PRRSV and PRV titres of 7.0log10TCID50/mL and 5.9log10TCID50/mL, respectively, were completely inactivated by SAEW at an ACC of ⩾50mg/L for 10min even though SAEW had no negative effect on the host cells. SAEW thus shows promise as a disinfectant for use on pig farms to reduce the spread of both PRRSV and PRV, and to limit the morbidity associated with those viruses.
Copyright © 2013 Elsevier Ltd. All rights reserved.

Hao X, Shen Z, Wang J, Zhang Q, Li B, Wang C, Cao W. In vitro inactivation of porcine reproductive and respiratory syndrome virus and pseudorabies virus by slightly acidic electrolyzed water. The veterinary journal 2013 [in press].

Friday, March 1, 2013

Effects on boar semen quality after infection with PRRSv: a case report

Abstract

ABSTRACT: The effect of porcine reproductive and respiratory syndrome virus (PRRSV) on semen quality was examined in a group of 11 spontaneously infected boars in a commercial boar stud. Semen samples were collected 4 weeks prior to 4 weeks post-infection (wpi). Infection with PRRSV of the European genotype subtype 1 (EU-1) was verified by specific quantitative real-time polymerase chain reaction (RT-PCR) in 36% of the serum samples. All boars seroconverted before 4 wpi and remained in normal condition throughout the study. Comparison of the percentage of morphologically intact spermatozoa revealed an increase of acrosome-defective spermatozoa (P = 0.012) between -4 and 4 wpi. Significant deleterious effects on semen quality were detected for membrane integrity when semen had been stored for 2 days after sampling. Analysis of sperm subpopulations in a thermoresistance test on day 7 after sampling revealed alterations in the percentage of circular, progressively motile spermatozoa (P = 0.013), in the percentage of non-linear, progressively motile spermatozoa (P = 0.01), and on the amplitude of lateral sperm head displacement (P = 0.047). There was no difference in the incidence of mitochondrially active spermatozoa (P = 0.075). Investigation of routine production data between pre- and post-infection status showed no differences on ejaculate volume (P = 0.417), sperm concentration (P = 0.788), and percentage of motile spermatozoa (P = 0.321). This case report provides insights into a potential control strategy for PRRSV outbreaks in boar studs.

PMID:
 
23442207
 
[PubMed - as supplied by publisher]


Schulze M, Revilla-FernÃndez S, Schmoll F, Grossfeld R, Griessler A. Effects on boar semen quality after infection with porcine reproductive and respiratory syndrome virus: a case report. Acta Veterinaria Scandinavica 2013;55(1):16-16.