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An update on genetic analysis of porcine reproductive and respiratory syndrome virus type 2 (PRRSV-2) in South America: identification of ORF5 sequences of lineage 1A, 1C and 1G. Arch Microbiol 2022; 204:367. [DOI: 10.1007/s00203-022-02976-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 05/04/2022] [Accepted: 05/11/2022] [Indexed: 11/02/2022]
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Ramos N, Mirazo S, Castro G, Cabrera K, Osorio F, Arbiza J. First-time detection of porcine reproductive and respiratory syndrome virus (PRRSV) infection in Uruguay. Transbound Emerg Dis 2018; 65:352-356. [PMID: 29330937 DOI: 10.1111/tbed.12813] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Indexed: 11/28/2022]
Abstract
Within the last two decades, several high-impact viruses have emerged in the global swine population, including porcine reproductive and respiratory syndrome virus (PRRSV). In Uruguay, the more recent serological survey for PRRSV and other notifiable diseases such as Aujeszky's disease virus (ADV) and classical swine fever virus (CSFV) dated from year 2000. The main purpose of this study was to update our information on the infection status of PRRSV, ADV and CSFV in Uruguayan pig herds, in order to keep informed about the epidemiological situation of these notifiable infections in the country. For serological testing, a total of 524 swine serum samples collected during the period 2014-2016 were assayed by commercial ELISAs. Our results revealed the (unexpected) presence of PRRSV antibodies in Uruguayan domestic swine herds and confirmed the absence of ADV and CSFV antibodies in all of the assessed samples. Following such initial finding, PRRSV antibodies were further investigated in 23 retrospective samples collected during 2010-2014. Thirteen of these 23 samples resulted seropositive. Subsequently, a molecular detection approach in frozen serum samples was implemented to confirm PRRSV infection, and viral RNA was identified by reverse transcription-nested polymerase chain reaction (RT-nPCR). Fourteen of 86 evaluated 2014-2016 samples resulted positive for viral RNA, while molecular analysis of four retrospective samples also revealed the presence of PRRSV type 2. Viral isolation of selected samples was carried out in porcine alveolar macrophages (PAM) and MARC 145 simian kidney cells, and the virus identity was confirmed by cytopathic effect (CPE) and immunofluorescence assay (IFA) using specific monoclonal antibodies for PRRSV nucleocapsid. Data reported here evidence for the first time the circulation of PRRSV type 2 in Uruguay, and retrospective serology results suggest that the virus has been infecting pigs in this country at least since 2011.
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Affiliation(s)
- N Ramos
- Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - S Mirazo
- Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - G Castro
- Área Suinos, Facultad de Veterinaria, Universidad de la República, Montevideo, Uruguay
| | - K Cabrera
- Asociación Uruguaya de productores de cerdos, Montevideo, Uruguay
| | - F Osorio
- Nebraska Center for Virology & School of Veterinary & Biomedical Sciences, University of Nebraska-Lincoln 140 MOLR, Lincoln, NE, USA
| | - J Arbiza
- Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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Van Noort A, Nelsen A, Pillatzki AE, Diel DG, Li F, Nelson E, Wang X. Intranasal immunization of pigs with porcine reproductive and respiratory syndrome virus-like particles plus 2', 3'-cGAMP VacciGrade™ adjuvant exacerbates viremia after virus challenge. Virol J 2017; 14:76. [PMID: 28403874 PMCID: PMC5389191 DOI: 10.1186/s12985-017-0746-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 03/30/2017] [Indexed: 11/26/2022] Open
Abstract
Background Porcine reproductive and respiratory syndrome virus (PRRSV) causes reproductive failure in pregnant sows and acute respiratory disease in young pigs. It is a leading infectious agent of swine respiratory complex, which has significant negative economic impact on the swine industry. Commercial markets currently offer both live attenuated and killed vaccines; however, increasing controversy exists about their efficacy providing complete protection. Virus-like particles (VLPs) possess many desirable features of a potent vaccine candidate and have been proven to be highly immunogenic and protective against virus infections. Here we explored the efficacy of PRRSV VLPs together with the use of a novel 2′, 3′-cGAMP VacciGrade™ adjuvant. Methods Animals were immunized twice intranasally with phosphate buffered saline (PBS), PRRSV VLPs, or PRRSV VLPs plus 2′, 3′-cGAMP VacciGrade™ at 2 weeks apart. Animals were challenged with PRRSV-23983 at 2 weeks post the second immunization. PRRSV specific antibody response and cytokines were measured. Viremia, clinical signs, and histological lesions were evaluated. Results PRRSV N protein specific antibody was detected in all animals at day 10 after challenge, but no significant difference was observed among the vaccinated and control groups. Surprisingly, a significantly higher viremia was observed in the VLPs and VLPs plus the adjuvant groups compared to the control group. The increased viremia is correlated with a higher interferon-α induction in the serum of the VLPs and the VLPs plus the adjuvant groups. Conclusions Intranasal immunizations of pigs with PRRSV VLPs and VLPs plus the 2′, 3′-cGAMP VacciGrade™ adjuvant exacerbates viremia. A higher level of interferon-α production, but not interferon-γ and IL-10, is correlated with enhanced virus replication. Overall, PRRSV VLPs and PRRSV VLPs plus the adjuvant fail to provide protection against PRRSV challenge. Different dose of VLPs and alternative route of vaccination such as intramuscular injection should be explored in the future studies to fully assess the feasibility of such a vaccine platform for PRRSV control and prevention.
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Affiliation(s)
- Alexandria Van Noort
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA
| | - April Nelsen
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA
| | - Angela E Pillatzki
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
| | - Diego G Diel
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
| | - Feng Li
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA.,Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA.,BioSNTR, South Dakota State University, Brookings, SD, 57007, USA
| | - Eric Nelson
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, 57007, USA
| | - Xiuqing Wang
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA.
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Porcine semen as a vector for transmission of viral pathogens. Theriogenology 2015; 85:27-38. [PMID: 26506911 DOI: 10.1016/j.theriogenology.2015.09.046] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/15/2015] [Accepted: 09/20/2015] [Indexed: 11/20/2022]
Abstract
Different viruses have been detected in porcine semen. Some of them are on the list of the World Organization for Animal Health (OIE), and consequently, these pathogens are of socioeconomic and/or public health importance and are of major importance in the international trade of animals and animal products. Artificial insemination (AI) is one of the most commonly used assisted reproductive technologies in pig production worldwide. This extensive use has enabled pig producers to benefit from superior genetics at a lower cost compared to natural breeding. However, the broad distribution of processed semen doses for field AI has increased the risk of widespread transmission of swine viral pathogens. Contamination of semen can be due to infections of the boar or can occur during semen collection, processing, and storage. It can result in reduced semen quality, embryonic mortality, endometritis, and systemic infection and/or disease in the recipient female. The presence of viral pathogens in semen can be assessed by demonstration of viable virus, nucleic acid of virus, or indirectly by measuring serum antibodies in the boar. The best way to prevent disease transmission via the semen is to assure that the boars in AI centers are free from the disease, to enforce very strict biosecurity protocols, and to perform routine health monitoring of boars. Prevention of viral semen contamination should be the primary focus because it is easier to prevent contamination than to eliminate viruses once present in semen. Nevertheless, research and development of novel semen processing treatments such as single-layer centrifugation is ongoing and may allow in the future to decontaminate semen.
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Sharma GK, Mahajan S, Matura R, Subramaniam S, Ranjan R, Biswal J, Rout M, Mohapatra JK, Dash BB, Sanyal A, Pattnaik B. Diagnostic assays developed for the control of foot-and-mouth disease in India. World J Virol 2015; 4:295-302. [PMID: 26279990 PMCID: PMC4534820 DOI: 10.5501/wjv.v4.i3.295] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 02/13/2015] [Accepted: 05/06/2015] [Indexed: 02/05/2023] Open
Abstract
Foot-and-mouth disease (FMD) is a highly contagious and economically devastating disease of livestock, primarily affecting cattle, buffalo and pigs. FMD virus serotypes O, A and Asia1 are prevalent in India and systematic efforts are on to control and eventually eradicate the disease from the country. FMD epidemiology is complex due to factors like co-circulation, extinction, emergence and re-emergence of genotypes/lineages within the three serotypes, animal movement, diverse farm practices and large number of susceptible livestock in the country. Systematic vaccination, prompt diagnosis, strict biosecurity measures, and regular monitoring of vaccinal immunity and surveillance of virus circulation are indispensible features for the effective implementation of the control measures. Availability of suitable companion diagnostic tests is very important in this endeavour. In this review, the diagnostic assays developed and validated in India and their contribution in FMD control programme is presented.
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Pepin BJ, Kittawornrat A, Liu F, Gauger PC, Harmon K, Abate S, Main R, Garton C, Hargrove J, Rademacher C, Ramirez A, Zimmerman J. Comparison of specimens for detection of porcine reproductive and respiratory syndrome virus infection in boar studs. Transbound Emerg Dis 2013; 62:295-304. [PMID: 23895185 DOI: 10.1111/tbed.12135] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Indexed: 11/30/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV)-contaminated semen from boars is a route of transmission to females, and early detection of PRRSV infection in boars is a key component in sow farm biosecurity. The purpose of this study was to determine the optimum diagnostic specimen(s) for the detection of acute PRRSV infection in boars. Individually housed boars (n = 15) were trained for semen and oral fluid collection and then vaccinated with a commercial PRRSV modified live virus vaccine. Starting on the day of vaccination and for 14 days thereafter, oral fluid specimens were collected daily from all boars. The 15 boars were subdivided into three groups of 5, and serum, blood swabs and 'frothy saliva' were collected at the time of semen collection on a 3-day rotation. Frothy saliva, derived from the submandibular salivary gland, is produced by aroused boars. Semen was centrifuged, and semen supernatant and cell fractions were tested separately. All samples were randomly ordered and then tested by PRRSV real-time quantitative reverse-transcription polymerase chain reaction assay (rRT-PCR) and PRRSV antibody ELISA. In this study, a comparison of serum, blood swab, and oral fluid rRT-PCR results found no statistically significant differences in the onset of detection or proportion of positives, but serum was numerically superior to oral fluids for early detection. Serum and oral fluid provided identical rRT-PCR results at ≥ 5 day post-vaccination. Likewise, the onset of detection of PRRSV antibody in serum, oral fluid and frothy saliva was statistically equivalent, with serum results again showing a numerical advantage. These results showed that the highest assurance of providing PRRSV-negative semen to sow farms should be based on rRT-PCR testing of serum collected at the time of semen collection. This approach can be augmented with oral fluid sampling from a random selection of uncollected boars to provide for statistically valid surveillance of the boar stud.
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Affiliation(s)
- B J Pepin
- Department of Veterinary Diagnostic and Production Animal Medicine, Iowa State University, Ames, IA, USA
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Han K, Seo HW, 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. Virol J 2013; 10:156. [PMID: 23687995 PMCID: PMC3663669 DOI: 10.1186/1743-422x-10-156] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 04/15/2013] [Indexed: 01/04/2023] Open
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-naïve 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.
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Schulze M, Revilla-Fernández 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 Vet Scand 2013; 55:16. [PMID: 23442207 PMCID: PMC3599264 DOI: 10.1186/1751-0147-55-16] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 02/21/2013] [Indexed: 11/23/2022] Open
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.
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Maes D, Nauwynck H, Rijsselaere T, Mateusen B, Vyt P, de Kruif A, Van Soom A. Diseases in swine transmitted by artificial insemination: An overview. Theriogenology 2008; 70:1337-45. [DOI: 10.1016/j.theriogenology.2008.06.018] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ramírez E, Moreno V, Díaz N, Osorio F, Ruiz A, Neira V, Quezada M. Evaluation of the pathogenicity and transmissibility of a chilean isolate of porcine reproductive and respiratory syndrome virus. Transbound Emerg Dis 2008; 55:115-24. [PMID: 18397499 DOI: 10.1111/j.1865-1682.2007.00991.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The objective of this study was to determine clinical features, shedding and transmission of a Chilean Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) strain upon experimental inoculation of 4-week-old pigs. Six groups of five animals each were used. The G1 (donor) group was inoculated with PRRSV, maintained in an isolation unit for 35 days, and sampled daily to determine shedding in mucosal secretions and faeces, viraemia and seroconversion. An uninfected control group (G6) was equally maintained and sampled under strict isolation. Four other groups (G2 to G5) were exposed to PRRSV via direct contact with G1 for 5-day periods in a staggered manner, throughout the 35-day period, and were later placed in an independent isolation unit to monitor infection status for 7 days. All the animals in G1 and G6 were killed at 35 days post-inoculation (dpi) and the contact groups at 12 days post-contact (dpc). Samples were obtained from diverse organs for histopathological, immunohistochemical (IHC) and virological analysis. No clinical symptoms were evident in any group, except for a transient fever observed in G1. Histopathologically, all the animals of G1 had interstitial pneumonia, although scarce PRRSV-positive cells were detected in the lung using IHC. PRRSV-positive cells (IHC) were detected in the lymphoid tissue of all animals in infected groups, but especially in G3 and G4. Viraemia was detected in G1 (3-35 dpi) and in the all contact groups (5-12 dpc). Likewise, ranging from 3 to 19 dpi, PRRSV was detected in at least one animal from the tonsils and lungs in all infected groups, in nasal and ocular secretions, saliva or faeces. These results indicate that the donor group excreted infectious PRRSV and was able to transmit the infection to susceptible pigs. The critical shedding period was 7-19 dpi, during which, most likely, transmission took place.
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Affiliation(s)
- E Ramírez
- Facultad de Medicina Veterinaria, Universidad de Concepción, Chillán, Chile
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Comparative antiviral and proviral factors in semen and vaccines for preventing viral dissemination from the male reproductive tract and semen. Anim Health Res Rev 2008; 9:59-69. [DOI: 10.1017/s1466252307001387] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
AbstractMany animal and human viruses are disseminated via semen, but there is little information on how to measure and stimulate protective antiviral immunity in the male reproductive tract and semen. This information is important since successful vaccination through the stimulation of protective immune responses could be a mechanism to prevent viral contamination of semen and subsequent wide spread viral dissemination. Even control of the infection by shortening the duration of viral shedding and lowering the viral load in semen would lessen the chances of viral dissemination through this route. This review will highlight the current knowledge of immunity in the male reproductive tract and summarize ‘antiviral’ as well as ‘proviral’ factors in semen such as cytokines, cells, antibodies, antimicrobial peptides, enzymes, hormones and growth factors. These factors must provide a fine balance between ‘immunosuppression’ in semen needed to protect sperm viability and ‘immunocompetency’ to prevent pathogen contamination. The review will also suggest continuing challenges to researchers for preventing viral dissemination via semen and propose a large animal model for continued research in this important area.
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Wang X, Eaton M, Mayer M, Li H, He D, Nelson E, Christopher-Hennings J. Porcine reproductive and respiratory syndrome virus productively infects monocyte-derived dendritic cells and compromises their antigen-presenting ability. Arch Virol 2006; 152:289-303. [PMID: 17031757 DOI: 10.1007/s00705-006-0857-1] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2005] [Accepted: 08/14/2006] [Indexed: 10/24/2022]
Abstract
Dendritic cells (DC) are potent antigen-presenting cells that play an important role in inducing primary antigen-specific immune responses. However, some viruses have evolved to specifically target DC to circumvent the host's immune responses for their persistence in the host. Porcine reproductive and respiratory syndrome virus (PRRSV) causes a persistent infection in susceptible animals. Although it is generally believed that the existence of PRRSV quasispecies is partly responsible for the virus persistence, other mechanisms of immune evasion or immune suppression may also exist. Here, we studied the role of DC in PRRSV persistence and immune suppression. Our results showed that PRRSV underwent a productive replication in pig monocyte-derived DC (Mo-DC) as measured by both immunofluorescence staining of viral nucleocapsid protein and virus titration assays, leading to cell death via both apoptosis and necrosis mechanisms. Additionally, PRRSV infection of Mo-DC resulted in reduced expression of MHC class I, MHC class II, CD14 and CD11b/c. This was in agreement with the impaired mixed lymphocyte reaction of PRRSV-infected Mo-DC compared to that of mock-infected Mo-DC. We also examined the cytokine profiles of PRRSV-infected Mo-DC using a quantitative ELISA method. Results indicated that no apparent change in the levels of IL-10, IL-12 and IFN-gamma was detected. Taken together, our data demonstrate that PRRSV productively infects Mo-DC and impairs the normal antigen presentation ability of Mo-DC by inducing cell death, down-regulating the expression of MHC class I, MHC class II, CD11b/c and CD14 and by inducing minimal Th1 cytokines.
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Affiliation(s)
- X Wang
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA.
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Christopher-Hennings J, Dammen M, Nelson E, Rowland R, Oberst R. Comparison of RNA extraction methods for the detection of porcine reproductive and respiratory syndrome virus from boar semen. J Virol Methods 2006; 136:248-53. [PMID: 16621036 DOI: 10.1016/j.jviromet.2006.03.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/14/2006] [Accepted: 03/20/2006] [Indexed: 11/20/2022]
Abstract
To detect Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in semen, various RNA extraction techniques have been utilized for RT-PCR, but rarely compared, to determine an optimized extraction protocol. Due to the viscosity, non-homogeneity, high cellularity and large volume of boar semen produced, difficulties can be encountered in obtaining RNA from the seminal cell fraction. This study compared six RNA extractions, five which used a commercially available kit (RNeasy, Qiagen Inc.) for use on highly cellular samples and a traditional phenol/chloroform procedure. All extractions were compared on serially diluted PRRSV "spiked" seminal cell fractions. The two methods resulting in recovery of the highest amount of RNA, which included a Qiashredder (Qiagen Inc.) (protocol 1) or cell lysis/centrifugation technique (protocol 3) preceding the RNeasy procedure were then compared using naturally infected semen samples from experimentally infected boars. Both protocols detected similar amounts of virus in "spiked" samples, but protocol 1 detected eight additional PRRSV-positive semen samples in naturally infected semen. This study demonstrated that semen "spiked" with PRRSV (cell-free virus) may not be representative of naturally infected semen samples (cell associated virus) for comparing extraction protocols, but did identify a useful extraction technique for boar semen.
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Affiliation(s)
- Jane Christopher-Hennings
- Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings, SD 57007-1396, USA.
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Wasilk A, Callahan JD, Christopher-Hennings J, Gay TA, Fang Y, Dammen M, Reos ME, Torremorell M, Polson D, Mellencamp M, Nelson E, Nelson WM. Detection of U.S., Lelystad, and European-like porcine reproductive and respiratory syndrome viruses and relative quantitation in boar semen and serum samples by real-time PCR. J Clin Microbiol 2004; 42:4453-61. [PMID: 15472293 PMCID: PMC522289 DOI: 10.1128/jcm.42.10.4453-4461.2004] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Transmission of porcine reproductive and respiratory syndrome virus (PRRSV) via boar semen has been documented. Since semen is widely disseminated for artificial insemination and the virus can cause significant health and economic consequences, it is essential to have well-validated, rapid diagnostic techniques to detect and quantitate the virus for diagnostic and research purposes. Previously, boar semen was tested by a nested PCR (nPCR) assay which was compared to the "gold standard" swine bioassay. A correlation of 94% was observed, indicating that, most of the time, PCR detected infectious virus. Subsequently, a real-time PCR targeting the 3' untranslated region of the PRRSV genome was compared with nPCR by testing 413 serum and semen samples from PRRSV-inoculated and control boars. There was 95% agreement between the results of the two tests, with the majority of samples with discordant results containing virus at the lower range of detection by the assays. The virus in all samples was quantitated by using a standard curve obtained by serial dilution of an in vitro transcript. By using the in vitro transcript, the lower limit of sensitivity was observed to be approximately 33 copies/ml. Reactivity with a panel of more than 100 PRRSV isolates from various geographical regions in the United States was also documented. No reactivity with nine nonrelated swine viruses was noted. A real-time PCR was also developed for the detection of the European Lelystad virus and the European-like PRRSV now found in the United States. In six of six PRRSV-inoculated boars, peak levels of viremia occurred at 5 days postinoculation (DPI) and were most consistently detectable throughout 22 DPI. In five of six boars, PRRSV was shed in semen for 0 to 2 days during the first 10 DPI; however, one of six boars shed the virus in semen through 32 DPI. Therefore, in general, the concentration and duration of PRRSV shedding in semen did not correlate with the quantity or duration of virus in serum. These differences warrant further studies into the factors that prevent viral replication in the reproductive tract.
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Affiliation(s)
- A Wasilk
- Department of Veterinary Science, South Dakota State University, Brookings, South Dakota 57007-1396, USA
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van Rijn PA, Wellenberg GJ, Hakze-van der Honing R, Jacobs L, Moonen PLJM, Feitsma H. Detection of economically important viruses in boar semen by quantitative RealTime PCR technology. J Virol Methods 2004; 120:151-60. [PMID: 15288957 PMCID: PMC7119495 DOI: 10.1016/j.jviromet.2004.04.014] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2003] [Revised: 04/10/2004] [Accepted: 04/14/2004] [Indexed: 11/20/2022]
Abstract
The objective of this study was to develop quantitative real-time polymerase chain reaction (ReTi-PCR) tests for the detection of five economically important viruses in swine semen namely, pseudorabies virus (PRV), classical swine fever virus (CSFV), foot-and-mouth disease virus (FMDV), swine vesicular disease virus (SVDV), and porcine reproductive and respiratory syndrome virus (PRRSV). Each ReTi-PCR test was validated for specificity, analytical sensitivity (detection limits), and experimental infection studies were performed to compare the conventional virus isolation methods with the newly developed ReTi-PCR tests. All five developed ReTi-PCR tests are very rapid compared to virus isolation, highly specific, and even more sensitive (lower detection limits) than conventional virus isolation methods for the detection of mentioned viruses in semen. In semen of experimentally infected boars, viruses were detected much earlier after infection and more frequently by ReTi-PCR tests than by virus isolations. The high throughput of these rapid ReTi-PCR tests makes it possible to screen large number of semen samples for the presence of viruses prior to insemination. This is a substantial advantage, in particular for boar semen the quality of which deteriorates quickly after storage. In general, the newly developed ReTi-PCR tests are valuable tools for the early, reliable and rapid detection of five economically important viruses, namely PRV, CSFV, FMDV, SVDV, and PRRSV in boar semen. These ReTi-PCR tests will improve the control of viral diseases transmitted via semen.
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Affiliation(s)
- Piet A van Rijn
- Central Institute for Animal Disease Control (CIDC-Lelystad), P.O. Box 2004, Lelystad 8204 AA, The Netherlands
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Prieto C, García C, Simarro I, Castro JM. Temporal localization of porcine reproductive and respiratory syndrome virus in reproductive tissues of experimentally infected boars. Theriogenology 2003; 60:1505-14. [PMID: 14519471 DOI: 10.1016/s0093-691x(03)00129-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) has been reported to be shed in the semen of infected boars. To determine whether the reproductive tissues could be a persistent source of virus and the possible origin of PRRSV found in semen of infected boars, 20 PRRSV-seronegative boars were intranasally inoculated with 5 x 10(6) median tissue culture infective doses (TCID50) of PRRSV and necropsied at different times post-inoculation (p.i.) from Day 2 to Day 37 p.i. Blood samples were collected before experimental inoculation, at necropsy and at different times p.i. At necropsy, epididymal semen and reproductive tissues were collected and the presence of the virus determined by virus isolation. The infection of the boars was demonstrated by the isolation of the virus from the sera of all inoculated boars and by seroconversion. PRRSV was detected in serum samples from Day 2 to Day 23 p.i., although the viremic period was largely dependent on the individual response to infection. Viral replication was proven within different reproductive tissues from Day 2 to Day 23 p.i., being most consistently found in the epididymus. In addition, PRRSV was isolated in semen from Day 4 to Day 10 p.i. The correlation of a diminished viremia and the inability to isolate PRRSV from semen or reproductive tissues may be due to one of two possibilities. First, viremia is responsible for most of the virus isolated from reproductive tissues due to the movement of PRRSV-infected cells out of the blood and into the tissues. Second, viremia may initially seed the reproductive tissues with PRRSV, and then the virus is produced into the reproductive tract and shed into semen at low levels.
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Affiliation(s)
- Cinta Prieto
- Departamento de Patología Animal I (Sanidad Animal), Facultad de Veterinaria, Universidad Complutense de Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
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17
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Mortensen S, Stryhn H, Søgaard R, Boklund A, Stärk KDC, Christensen J, Willeberg P. Risk factors for infection of sow herds with porcine reproductive and respiratory syndrome (PRRS) virus. Prev Vet Med 2002; 53:83-101. [PMID: 11821139 DOI: 10.1016/s0167-5877(01)00260-4] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In 1992, the porcine reproductive and respiratory syndrome virus (PRRSV) of European type (PRRSV-EU) was introduced in Denmark. By 1996, the virus had spread to approximately 25% of the Danish herds. In January 1996, a modified-live vaccine based on the American type of the virus (PRRSV-US) was used in replacement boars for Danish artificial insemination (AI) centres and from July 1996, the vaccine was used in PRRSV-EU infected herds for prevention of disease. Soon after vaccine introduction, PRRSV non-infected herds experienced outbreaks of disease due to infection with PRRSV-US. In this study, we investigated the risk factors (biosecurity level, animals, exposure from PRRSV-US-infected neighbour herds, semen, herd size, pig density and herd density) for infection with PRRSV-US in a cohort of 1071 sow herds; we used a nested case-control study. The retrospective observation period lasted from June 1996 (when they all were non-infected) to October 1997. Seventy-three non-vaccinated, closed sow herds became infected with the vaccine strain during this period. Each case herd was matched with two control herds from the cohort (controls had not been infected at the time of infection in the case herds). The data were analysed using a Cox-regression model. The hazard of infection increased significantly with exposure from PRRSV-US-infected neighbouring herds, purchase of animals from herds incubating PRRSV-US infection, increasing herd size and purchase of semen from boars at PRRSV-US-infected AI centres. The results are consistent with the modified-live vaccine strain spread to other herds by trade with animals and semen and by neighbour (area) transmission. We suggest that virus spread by aerosols was a frequent mode of transmission.
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Affiliation(s)
- Sten Mortensen
- Department of Animal Science and Animal Health, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark.
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18
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Oleksiewicz MB, Bøtner A, Normann P. Semen from boars infected with porcine reproductive and respiratory syndrome virus (PRRSV) contains antibodies against structural as well as nonstructural viral proteins. Vet Microbiol 2001; 81:109-25. [PMID: 11376957 DOI: 10.1016/s0378-1135(01)00341-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The seminal excretion of antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) was examined in a group of five boars experimentally infected by the nasopharyngeal route. By using phage-displayed peptide epitopes from the PRRSV replicase and envelope glycoproteins as ELISA antigen, we were able to separately and specifically assay antibody responses against structural and nonstructural viral proteins. Antibodies against structural as well as nonstructural viral proteins were consistently found in the semen of all boars, beginning from 1-4 weeks postinfection. This is the first report documenting the presence of anti-PRRSV antibodies in boar semen. Seminal antiviral IgA was also detected, and we observed a correlation between seminal IgA responses against nonstructural viral proteins, and the duration of PRRSV RNA excretion in semen. The implications of these findings for the diagnostics and pathogenesis of venereal PRRSV infection are discussed.
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Affiliation(s)
- M B Oleksiewicz
- Danish Veterinary Institute for Virus Research, Lindholm, 4771 Kalvehave, Denmark.
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Christopher-Hennings J, Holler LD, Benfield DA, Nelson EA. Detection and duration of porcine reproductive and respiratory syndrome virus in semen, serum, peripheral blood mononuclear cells, and tissues from Yorkshire, Hampshire, and Landrace boars. J Vet Diagn Invest 2001; 13:133-42. [PMID: 11289209 DOI: 10.1177/104063870101300207] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Because transmission of porcine reproductive and respiratory syndrome virus (PRRSV) can occur through boar semen, it is important to identify persistently infected boars. However, even for boars given the same PRRSV strain and dose, variability in the duration of viral shedding in semen has been observed, suggesting that host factors are involved in PRRSV persistence. To determine whether there are host genetic factors, particularly litter and breed differences related to the persistence of PRRSV, 3 litters from 3 purebred swine breeds were used for this study. It was also determined whether PRRSV could be detected for a longer period of time in serum, semen, or peripheral blood mononuclear cells (PBMC) and if PRRSV could still be detected in tissues after these antemortem specimens were PRRSV negative for a minimum of 2-3 weeks. Three Hampshire, 3 Yorkshire, and 2 Landrace PRRSV-naive boars were obtained and inoculated intranasally with a wild-type PRRSV isolate (SD-23983). All boars within each breed were from the same litter, and litters were within 9 days of age. Serum and PBMC were collected twice weekly from each boar and analyzed for the presence of PRRSV by virus isolation and the polymerase chain reaction (PCR). Serum was also used to obtain virus neutralization titers and enzyme-linked immunosorbent assay S/P values. Semen was collected twice weekly from 7 of 8 boars and analyzed by PCR. After all specimens were PRRSV negative for a minimum of 2-3 weeks, each boar was euthanized, and 21 tissues plus saliva, serum, feces, and urine were collected. All postmortem specimens were evaluated by virus isolation. Specimens that were PRRSV negative by virus isolation were then evaluated by PCR. The mean number of days (+/-SD) for the duration of PRRSV shedding in semen was 51+/-26.9 days, 7.5+/-4.9 days, and 28.3+/-17.5 days for Landrace, Yorkshire, and Hampshire boars, respectively. Because of small sample sizes and large SDs, the differences in duration of PRRSV shedding in semen between breeds were not considered significant. However, the trend suggested that Yorkshire boars were more resistant to PRRSV shedding in semen than were Landrace boars, requiring further investigation using a larger numbers of boars. PRRSV was detected for a longer period in semen than in serum or PBMC in 4 of 7 boars. Viremia could be detected for a longer period in serum than in PBMC in 6 of 8 boars. After a minimum of 2-3 weeks of PRRSV-negative serum, semen, and PBMC, PRRSV could still be detected in the tonsil of 3 of 8 boars by virus isolation, indicating that boars still harbor PRRSV within the tonsil even though antemortem specimens are PRRSV negative.
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Affiliation(s)
- J Christopher-Hennings
- Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings 57007-1396, USA
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20
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21
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Kaiser TJ, Christopher-Hennings J, Nelson EA. Measurement of immunoglobulin G, A and M concentrations in boar seminal plasma. Theriogenology 2000; 54:1171-84. [PMID: 11131334 DOI: 10.1016/s0093-691x(00)00424-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
How the immune system relates to the boar reproductive tract is not well defined. This is an important area of study because disease-causing agents may be transmitted through boar semen. We have previously identified porcine reproductive and respiratory syndrome virus (PRRSV) in boar semen and wanted to identify PRRSV-specific antibodies within seminal plasma. However, literature documenting total immunoglobulin concentration or the predominant immunoglobulin isotype in boar semen was not available. Therefore, we developed a sandwich enzyme-linked immunoassay (ELISA) to quantitate total IgG, IgA and IgM in seminal plasma from 16 healthy, nonvaccinated, adult boars (n = 102 semen samples). In seminal plasma, IgG was the predominant isotype followed by IgA and IgM. Mean levels +/- the standard deviation followed by the 95% confidence interval of IgG, IgA and IgM were 23.2 +/- 14 microg/mL (15.5 to 31.0), 4.8 +/- 2.5 microg/mL (3.5 to 6.2) and 3.7 +/- 1.7 microg/mL (2.7 to 4.7), respectively. These concentrations of immunoglobulins in seminal plasma were considerably lower than in other swine secretions, which might allow for the survival of infectious agents in boar semen.
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Affiliation(s)
- T J Kaiser
- Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings 57007, USA
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Wagstrom EA, Yoon KJ, Cook C, Zimmerman JJ. Diagnostic performance of a reverse transcription-polymerase chain reaction test for porcine reproductive and respiratory syndrome virus. J Vet Diagn Invest 2000; 12:75-8. [PMID: 10690783 DOI: 10.1177/104063870001200116] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- E A Wagstrom
- Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames 50011, USA
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Oleksiewicz M, Bøtner A, Madsen K, Storgaard T. Sensitive detection and typing of porcine reproductive and respiratory syndrome virus by RT-PCR amplification of whole viral genes. Vet Microbiol 1998; 64:7-22. [PMID: 9874099 PMCID: PMC7117142 DOI: 10.1016/s0378-1135(98)00254-5] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Following the recent use of a live vaccine against porcine reproductive and respiratory syndrome virus (PRRSV) in Denmark, both American (vaccine) and European-type PRRSV now coexist in Danish herds. This situation highlighted a requirement for supplementary tests for precise virus-typing. As a result, we developed a RT-PCR assay able to detect as well as type PRRSV. To provide maximal sequence information, complete viral open reading frames (ORFs 5 and 7) were targeted for amplification. The RT-PCR test was able to amplify complete PRRSV ORFs from complex materials such as boar semen containing as little as 1 TCID50 ml(-1) of PRRSV. Typing of viruses was accomplished by any one of three strategies: (i) use of type-specific PCR primers, (ii) size determination of ORF 7 amplicons, (iii) DNA sequencing. All three typing strategies showed complete concordance with the currently used method of typing with monoclonal antibodies (MAbs) when used on a panel of PRRSV field isolates covering the period 1992-1997. The ORF 7-based test had particularly desirable characteristics, namely, highly sensitive detection of PRRSV without apparent type bias, typing of the detected virus, discrimination between pure and mixed virus populations, and semi-quantitative assessment of type ratios in mixed populations, all in a single PCR reaction. In addition, the obtained sequence data were used to predict two simple and rapid strategies (single-enzyme restriction length polymorphy analysis and oligonucleotide hybridization) for confirmation of the specificity of ORF 7 RT-PCR reactions. As such, the RT-PCR assay provides a new, powerful diagnostic tool to study the population dynamics between present and emerging PRRSV-types.
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Affiliation(s)
- M.B Oleksiewicz
- Danish Veterinary Institute for Virus Research, Lindholm4771 KalvehaveDenmark
| | - A Bøtner
- Danish Veterinary Institute for Virus Research, Lindholm4771 KalvehaveDenmark
| | - K.G Madsen
- Danish Institute of Plant and Soil Science, Research Center, Flakkebjerg4200 SlagelseDenmark
| | - T Storgaard
- Danish Veterinary Institute for Virus Research, Lindholm4771 KalvehaveDenmark
- Corresponding author. Tel.: +45-5586-0276; fax: +45-5586-0300; e-mail:
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Christopher-Hennings J, Nelson EA, Nelson JK, Rossow KD, Shivers JL, Yaeger MJ, Chase CC, Garduno RA, Collins JE, Benfield DA. Identification of porcine reproductive and respiratory syndrome virus in semen and tissues from vasectomized and nonvasectomized boars. Vet Pathol 1998; 35:260-7. [PMID: 9684969 DOI: 10.1177/030098589803500404] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Previous studies have indicated that porcine reproductive and respiratory syndrome virus (PRRSV) can be identified in and transmitted through boar semen. However, the site(s) of replication indicating the origin of PRRSV in semen has not been identified. To determine how PRRSV enters boar semen, five vasectomized and two nonvasectomized PRRSV-seronegative boars were intranasally inoculated with PRRSV isolate VR-2332. Semen was collected three times weekly from each boar and separated into cellular and cell-free (seminal plasma) fractions. Both fractions were evaluated by reverse transcriptase nested polymerase chain reaction (RT-nPCR) for the presence of PRRSV RNA. Viremia and serostatus were evaluated once weekly, and boars were euthanatized 21 days postinoculation (DPI). Tissues were collected and evaluated by RT-nPCR, virus isolation (VI), and immunohistochemistry to identify PRRSV RNA, infectious virus, or viral antigen, respectively. PRRSV RNA was identified in semen from all vasectomized and nonvasectomized boars and was most consistently found in the cell fraction, within cells identified with a macrophage marker. Viral replication as determined by VI was predominately found within lymphoid tissue. However, PRRSV RNA was widely disseminated throughout many tissues, including the reproductive tract at 21 DPI. These results indicate that PRRSV can enter semen independent of testicular or epididymal tissues, and the source of PRRSV in semen is virus-infected monocytes/macrophages or non-cell-associated virus in serum. PRRSV-infected macrophages in semen may result from infection of local tissue macrophages or may originate from PRRSV-infected circulating monocytes or macrophages.
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Affiliation(s)
- J Christopher-Hennings
- Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings 57007-1396, USA
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Shin J, Bautista EM, Kang YB, Molitor TW. Quantitation of porcine reproductive and respiratory syndrome virus RNA in semen by single-tube reverse transcription-nested polymerase chain reaction. J Virol Methods 1998; 72:67-79. [PMID: 9672134 DOI: 10.1016/s0166-0934(98)00025-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is in boar semen for extended periods of time as determined by reverse transcription-nested polymerase chain reaction (RT-nPCR) assay. The concentration of PRRSV RNA in semen and the biological significance of the detection level, however, remain to be resolved. In order to determine the concentration of PRRSV VR-2332 (a prototypic strain of North American isolates) in semen following infection, we established a 'standard curve'-quantitative competitive (SC-QC)-RT-nPCR assay as well as an equimolar QC-RT-nPCR assay. A deletion-type competitor RNA derived from the Lelystad virus, a European strain of PRRSV, ORF-7 gene standard which shares the nested sets of primer recognition sequences with the VR-2332 ORF-7 gene was used as an internal standard. The equimolar QC-RT-nPCR assay results revealed that the number of copies of PRRSV RNA in 1 TCID50/ml of virus derived from CL-2621 cell culture supernatants varied depending upon the type of samples in which virus was added; 143 +/- 24.0 and 266.5 +/- 48.5 copies in serum and semen samples spiked with PRRSV VR-2332, respectively. For the establishment of SC-QC-RT-nPCR assay, a standard curve was generated from band intensity ratios versus a series of known initial numbers of wild-type RNA copies which were quantified by the equimolar QC-RT-nPCR assay. Various initial numbers of copies of wild-type PRRSV RNA and each band intensity ratio with 1000 copies of competitor RNA were well correlated within the range of 100 to 200,000 copies (R2 = 0.947). A 'standard curve' quantitation assay using competitive single-tube RT-nPCR will offer a rapid and reliable way to quantify low concentrations of PRRSV RNA in semen.
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Affiliation(s)
- J Shin
- Department of Clinical and Population Sciences, University of Minnesota, St. Paul 55108, USA
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