Infection dynamics, transmission, and evolution after an outbreak of porcine reproductive and respiratory syndrome virus
Clilvert, Hepzibar (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Martín-Valls, Gerard (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Li, Yanli (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Martín Castillo, Margarita (Universitat Autònoma de Barcelona. Departament de Ciència Animal i dels Aliments)
Cortey, Martí (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Mateu de Antonio, Enrique María (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)

Data:	2023
Resum:	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.
Ajuts:	Ministerio de Ciencia e Innovación AGL2017-87073-R Ministerio de Ciencia e Innovación FPU18/04259 Ministerio de Economía y Competitividad RyC-2015-17154
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Porcine reproductive and respiratory syndrome virus ; Genetic diversity ; Evolution ; Founder effect ; Super-spreader ; Neutralizing antibodies
Publicat a:	Frontiers in microbiology, Vol. 14 (february 2023) , ISSN 1664-302X

DOI: 10.3389/fmicb.2023.1109881
PMID: 36846785

14 p, 2.8 MB

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