Goal: This examine investigates the long-term evolutionary dynamics of porcine reproductive and respiratory syndrome virus (PRRSV-1) in an endemically contaminated and vaccinated pig herd.
Strategies: Over a one yr and a half interval, piglets from seven farrowing batches in a 300-sow PRRSV-vaccinated farm have been monitored from beginning to 9 weeks of age by RT-qPCR. Eighty-five PRRSV-positive samples have been subjected to complete genome sequencing, and 251 samples to ORF5 sequencing. Farm-specific PRRSV variants’ affect on anti-PRRSV antibodies was evaluated utilizing ELISA and neutralizing antibody assays. The replication kinetics and cytokine inhibition capabilities (IFN-α and TNF-α) of those variants have been assessed in porcine alveolar macrophages.
Outcomes: The examine revealed fluctuating PRRSV-1 incidences in farrowing items and nurseries, attributed to 2 key evolutionary occasions: an escape variant emergence and a lateral introduction of a brand new pressure. Initially, pressure 1 variant α was swiftly changed inside weeks by variant 1β (99.5% genomic similarity), with twenty-five amino acid mutations, primarily in nsp1α, GP2, GP3, and GP5, together with a further glycosylation web site and a deletion downstream the neutralization epitope of GP5. This shift to 1β correlated with elevated incidence in nurseries and better viral masses, with sera from 1α-exposed animals exhibiting diminished neutralization towards 1β. Constantly for in vitro assays, variant 1β demonstrated enhanced replication in porcine alveolar macrophages however no distinction concerning IFN-α or TNF-α responses. Later, a brand new pressure (pressure 2, 83.3% similarity to pressure 1) emerged and led to incidence resurgence due to the low cross reactivity with the earlier antibodies.
Conclusion: The examine highlights PRRSV’s speedy adaptability and challenges in controlling its unfold, underscoring the need for simpler vaccines and eradication approaches.
Clilverd H, Li Y, Martín-Valls G, Aguirre L, Martín M, Cortey M, Mateu E. Collection of viral variants with enhanced transmission and diminished neutralization susceptibility alongside lateral introductions might clarify the persistence of porcine reproductive and respiratory syndrome virus in vaccinated breeding herds. Virus Evolution. 2024: veae041. https://doi.org/10.1093/ve/veae041
