New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus

ABSTRACT Porcine reproductive and respiratory syndrome virus (PRRSV) has a restricted host specificity, primarily infecting porcine macrophages. Notably, an exception to such macrophage-restricted tropism has been observed in sexually active boars, where the virus infects and induces apoptosis in th...

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Main Authors: Kassandra Durazo-Martínez, Fernando A. Osorio, Gustavo Delhon, Jesús Hernández, Hiep L. X. Vu
Format: Article
Language:English
Published: American Society for Microbiology 2025-04-01
Series:Microbiology Spectrum
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Online Access:https://journals.asm.org/doi/10.1128/spectrum.02964-24
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author Kassandra Durazo-Martínez
Fernando A. Osorio
Gustavo Delhon
Jesús Hernández
Hiep L. X. Vu
author_facet Kassandra Durazo-Martínez
Fernando A. Osorio
Gustavo Delhon
Jesús Hernández
Hiep L. X. Vu
author_sort Kassandra Durazo-Martínez
collection DOAJ
description ABSTRACT Porcine reproductive and respiratory syndrome virus (PRRSV) has a restricted host specificity, primarily infecting porcine macrophages. Notably, an exception to such macrophage-restricted tropism has been observed in sexually active boars, where the virus infects and induces apoptosis in the germinal epithelium, resulting in viral dissemination in the ejaculate. Whether this phenomenon occurs in prepubertal animals remains unclear. In this study, we isolated spermatogonia stem cells (SSCs) from neonatal pigs and cultured them in vitro. These SSC cultures formed morula-like colonies, exhibited alkaline phosphatase activity—a characteristic of stem cells—and expressed protein gene product 9.5, a marker of SSCs. Notably, the SSC cultures supported PRRSV replication with kinetics similar to that observed in porcine alveolar macrophages. To assess the testicular tropism of PRRSV in prepuberal animals, 28-day-old male pigs were infected with a virulent PRRSV strain. Testicular tissues were sequentially analyzed using a combination of in situ hybridization for PRRSV RNA and immunohistochemistry for specific cellular markers. Unlike in sexually active boars, PRRSV did not infect the spermatogonia cells within the seminiferous tubules of prepubertal pigs. Instead, the virus primarily infected macrophages and myoid cells located in the interstitium and peritubular areas. It appeared that the anatomical separation of spermatogonia from the basal membrane of the seminiferous tubules in prepubertal pigs prevents these cells from being infected by PRRSV. Overall, our findings offer valuable insights into the age-dependent testicular tropism of PRRSV.IMPORTANCEContaminated boar semen used in artificial insemination has significantly contributed to the global spread of porcine reproductive and respiratory syndrome virus (PRRSV), a virus that typically infects only cells within the monocyte and macrophage lineages. Our study reveals that spermatogonia stem cells (SSCs) from neonatal piglets are also susceptible to PRRSV, suggesting that non-macrophage cells can be infected by the virus. However, despite this susceptibility, PRRSV-infected cells were not found in the seminiferous tubules of prepubertal male pigs inoculated with a virulent PRRSV strain. This contrasts with sexually mature boars, where PRRSV-infected cells were prominently observed within the seminiferous tubules. The discrepancy is likely due to anatomical differences between the seminiferous tubules of sexually mature boars and prepubertal pigs. These findings provide new insights into PRRSV pathogenesis. Additionally, the ex vivo SSC culture provides a valuable model for identifying new viral receptors necessary for PRRSV infection and for investigating the virus’s impact on spermatogenesis.
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spelling doaj-art-57bb4a99cec24d9db5d64ec06aada5e52025-08-20T03:44:33ZengAmerican Society for MicrobiologyMicrobiology Spectrum2165-04972025-04-0113410.1128/spectrum.02964-24New insights into the testicular tropism of porcine reproductive and respiratory syndrome virusKassandra Durazo-Martínez0Fernando A. Osorio1Gustavo Delhon2Jesús Hernández3Hiep L. X. Vu4Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USANebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USASchool of Veterinary Medicine and Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, Nebraska, USALaboratorio de Inmunología, Centro de Investigación en Alimentación y Desarrollo A.C. (CIAD, A.C.), Hermosillo, Sonora, MexicoNebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, Nebraska, USAABSTRACT Porcine reproductive and respiratory syndrome virus (PRRSV) has a restricted host specificity, primarily infecting porcine macrophages. Notably, an exception to such macrophage-restricted tropism has been observed in sexually active boars, where the virus infects and induces apoptosis in the germinal epithelium, resulting in viral dissemination in the ejaculate. Whether this phenomenon occurs in prepubertal animals remains unclear. In this study, we isolated spermatogonia stem cells (SSCs) from neonatal pigs and cultured them in vitro. These SSC cultures formed morula-like colonies, exhibited alkaline phosphatase activity—a characteristic of stem cells—and expressed protein gene product 9.5, a marker of SSCs. Notably, the SSC cultures supported PRRSV replication with kinetics similar to that observed in porcine alveolar macrophages. To assess the testicular tropism of PRRSV in prepuberal animals, 28-day-old male pigs were infected with a virulent PRRSV strain. Testicular tissues were sequentially analyzed using a combination of in situ hybridization for PRRSV RNA and immunohistochemistry for specific cellular markers. Unlike in sexually active boars, PRRSV did not infect the spermatogonia cells within the seminiferous tubules of prepubertal pigs. Instead, the virus primarily infected macrophages and myoid cells located in the interstitium and peritubular areas. It appeared that the anatomical separation of spermatogonia from the basal membrane of the seminiferous tubules in prepubertal pigs prevents these cells from being infected by PRRSV. Overall, our findings offer valuable insights into the age-dependent testicular tropism of PRRSV.IMPORTANCEContaminated boar semen used in artificial insemination has significantly contributed to the global spread of porcine reproductive and respiratory syndrome virus (PRRSV), a virus that typically infects only cells within the monocyte and macrophage lineages. Our study reveals that spermatogonia stem cells (SSCs) from neonatal piglets are also susceptible to PRRSV, suggesting that non-macrophage cells can be infected by the virus. However, despite this susceptibility, PRRSV-infected cells were not found in the seminiferous tubules of prepubertal male pigs inoculated with a virulent PRRSV strain. This contrasts with sexually mature boars, where PRRSV-infected cells were prominently observed within the seminiferous tubules. The discrepancy is likely due to anatomical differences between the seminiferous tubules of sexually mature boars and prepubertal pigs. These findings provide new insights into PRRSV pathogenesis. Additionally, the ex vivo SSC culture provides a valuable model for identifying new viral receptors necessary for PRRSV infection and for investigating the virus’s impact on spermatogenesis.https://journals.asm.org/doi/10.1128/spectrum.02964-24PRRSVspermatogonia stem cellstesticular tropismswine viruses
spellingShingle Kassandra Durazo-Martínez
Fernando A. Osorio
Gustavo Delhon
Jesús Hernández
Hiep L. X. Vu
New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
Microbiology Spectrum
PRRSV
spermatogonia stem cells
testicular tropism
swine viruses
title New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
title_full New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
title_fullStr New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
title_full_unstemmed New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
title_short New insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
title_sort new insights into the testicular tropism of porcine reproductive and respiratory syndrome virus
topic PRRSV
spermatogonia stem cells
testicular tropism
swine viruses
url https://journals.asm.org/doi/10.1128/spectrum.02964-24
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