Levels of neutralizing antibodies against resident farm strain or vaccine strain are not indicators of protection against PRRSV-1 vertical transmission under farm conditions

BMC Veterinary Research

Research

Yanli Li¹  Gerard Eduard Martin-Valls¹  Hepzibar Clilverd¹  Martí Cortey¹  Jordi Soto¹  Enric Mateu¹ 

[1] Departament de Sanitat i Anatomia Animals, Facultat de Veterinària, Travessera dels Turons S/N, Universitat Autònoma de Barcelona, 08193, Cerdanyola del Vallès, Spain;

关键词: Porcine reproductive and respiratory virus;    Neutralizing antibodies;    Broadly neutralizing antibodies;    Vertical transmission;   

DOI  :  10.1186/s12917-023-03785-z

 received in 2023-03-12, accepted in 2023-10-10,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundVertical transmission is key for the maintenance of porcine reproductive and respiratory syndrome virus (PRRSV) infection. In vaccinated farms, vertical transmission can still occur despite sows having some level of immunity because of repeated vaccination or contact with the wild-type virus. The present study aimed to correlate the age of sows and the amplitude of neutralizing antibodies (Nab) (heterologous neutralization) with PRRSV-1 vertical transmission (VT). For this purpose, umbilical cords of 1,554 newborns (corresponding to 250 litters) were tested for PRRSV by RT-PCR in two PRRSV-unstable vaccinated farms. In parallel, the sows were bled after farrowing and the levels of antibodies were determined by ELISA and by the viral neutralization test against the vaccine virus, the virus circulating in the farm, and other unrelated contemporary PRRSV-1 strains. The relationship between the parity and the probability of delivering infected piglets and the presence of broadly Nabs examined.ResultsThe proportion of VT events in the two examined farms ranged from 18.9% to 23.0%. Young sows (parity 1–2) were 1.7 times more likely to have VT than older sows (p < 0.05). Despite higher ELISA S/P antibody ratios in younger sows (p < 0.05), NAb against the resident farm strain were at a similar level between sows delivering infected and healthy piglets regardless of age, mostly with low titers (2–3 log2). The titers of NAb against the vaccine virus were also low, and no correlations with VT were observed. When a panel of another 4 strains (1 isolated in the 1990s, and 3 contemporary strains) were used for the neutralization test, most sow sera were not capable of neutralizing the contemporary strains.ConclusionsTiters of NAb could not be correlated with the occurrence of PRRSV VT. The amplitude of NAb present in most vaccinated sows is limited with a considerable proportion unresponsive regarding NAb production.

【 授权许可】

CC BY   
© BioMed Central Ltd., part of Springer Nature 2023

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