Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus
The present study was aimed at describing the infection dynamics, transmission, and evolution of porcine reproductive and respiratory syndrome virus (PRRSV) after an outbreak in a 300-sow farrow-to-wean farm that was implementing a vaccination program. Three subsequent batches of piglets (9–11 litte...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2023-02-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmicb.2023.1109881/full |
| _version_ | 1828038311415906304 |
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| author | Hepzibar Clilverd Gerard Martín-Valls Yanli Li Marga Martín Martí Cortey Enric Mateu |
| author_facet | Hepzibar Clilverd Gerard Martín-Valls Yanli Li Marga Martín Martí Cortey Enric Mateu |
| author_sort | Hepzibar Clilverd |
| collection | DOAJ |
| description | The present study was aimed at describing the infection dynamics, transmission, and evolution of porcine reproductive and respiratory syndrome virus (PRRSV) after an outbreak in a 300-sow farrow-to-wean farm that was implementing a vaccination program. Three subsequent batches of piglets (9–11 litters/batch) were followed 1.5 (Batch 1), 8 (Batch 2), and 12 months after (Batch 3) from birth to 9 weeks of age. The RT-qPCR analysis showed that shortly after the outbreak (Batch 1), one third of sows were delivering infected piglets and the cumulative incidence reached 80% by 9 weeks of age. In contrast, in Batch 2, only 10% animals in total got infected in the same period. In Batch 3, 60% litters had born-infected animals and cumulative incidence rose to 78%. Higher viral genetic diversity was observed in Batch 1, with 4 viral clades circulating, of which 3 could be traced to vertical transmission events, suggesting the existence of founder viral variants. In Batch 3 though only one variant was found, distinguishable from those circulating previously, suggesting that a selection process had occurred. ELISA antibodies at 2 weeks of age were significantly higher in Batch 1 and 3 compared to Batch 2, while low levels of neutralizing antibodies were detected in either piglets or sows in all batches. In addition, some sows present in Batch 1 and 3 delivered infected piglets twice, and the offspring were devoid of neutralizing antibodies at 2 weeks of age. These results suggest that a high viral diversity was featured at the initial outbreak followed by a phase of limited circulation, but subsequently an escape variant emerged in the population causing a rebound of vertical transmission. The presence of unresponsive sows that had vertical transmission events could have contributed to the transmission. Moreover, the records of contacts between animals and the phylogenetic analyses allowed to trace back 87 and 47% of the transmission chains in Batch 1 and 3, respectively. Most animals transmitted the infection to 1–3 pen-mates, but super-spreaders were also identified. One animal that was born-viremic and persisted as viremic for the whole study period did not contribute to transmission. |
| first_indexed | 2024-04-10T16:25:10Z |
| format | Article |
| id | doaj.art-da897b4507d949c1bd6214d1871e5cbd |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-04-10T16:25:10Z |
| publishDate | 2023-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-da897b4507d949c1bd6214d1871e5cbd2023-02-09T08:00:59ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2023-02-011410.3389/fmicb.2023.11098811109881Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virusHepzibar ClilverdGerard Martín-VallsYanli LiMarga MartínMartí CorteyEnric MateuThe present study was aimed at describing the infection dynamics, transmission, and evolution of porcine reproductive and respiratory syndrome virus (PRRSV) after an outbreak in a 300-sow farrow-to-wean farm that was implementing a vaccination program. Three subsequent batches of piglets (9–11 litters/batch) were followed 1.5 (Batch 1), 8 (Batch 2), and 12 months after (Batch 3) from birth to 9 weeks of age. The RT-qPCR analysis showed that shortly after the outbreak (Batch 1), one third of sows were delivering infected piglets and the cumulative incidence reached 80% by 9 weeks of age. In contrast, in Batch 2, only 10% animals in total got infected in the same period. In Batch 3, 60% litters had born-infected animals and cumulative incidence rose to 78%. Higher viral genetic diversity was observed in Batch 1, with 4 viral clades circulating, of which 3 could be traced to vertical transmission events, suggesting the existence of founder viral variants. In Batch 3 though only one variant was found, distinguishable from those circulating previously, suggesting that a selection process had occurred. ELISA antibodies at 2 weeks of age were significantly higher in Batch 1 and 3 compared to Batch 2, while low levels of neutralizing antibodies were detected in either piglets or sows in all batches. In addition, some sows present in Batch 1 and 3 delivered infected piglets twice, and the offspring were devoid of neutralizing antibodies at 2 weeks of age. These results suggest that a high viral diversity was featured at the initial outbreak followed by a phase of limited circulation, but subsequently an escape variant emerged in the population causing a rebound of vertical transmission. The presence of unresponsive sows that had vertical transmission events could have contributed to the transmission. Moreover, the records of contacts between animals and the phylogenetic analyses allowed to trace back 87 and 47% of the transmission chains in Batch 1 and 3, respectively. Most animals transmitted the infection to 1–3 pen-mates, but super-spreaders were also identified. One animal that was born-viremic and persisted as viremic for the whole study period did not contribute to transmission.https://www.frontiersin.org/articles/10.3389/fmicb.2023.1109881/fullporcine reproductive and respiratory syndrome virusgenetic diversityevolutionfounder effectsuper-spreaderneutralizing antibodies |
| spellingShingle | Hepzibar Clilverd Gerard Martín-Valls Yanli Li Marga Martín Martí Cortey Enric Mateu Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus Frontiers in Microbiology porcine reproductive and respiratory syndrome virus genetic diversity evolution founder effect super-spreader neutralizing antibodies |
| title | Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus |
| title_full | Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus |
| title_fullStr | Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus |
| title_full_unstemmed | Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus |
| title_short | Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus |
| title_sort | infection dynamics transmission and evolution after an outbreak of porcine reproductive and respiratory syndrome virus |
| topic | porcine reproductive and respiratory syndrome virus genetic diversity evolution founder effect super-spreader neutralizing antibodies |
| url | https://www.frontiersin.org/articles/10.3389/fmicb.2023.1109881/full |
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