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JSM Veterinary Medicine and Research

Field Evaluation of a Lineage 7 PRRS MLV in Mitigating the Impact of Nadc34-Like PRRS Infection in Korean Pig Farm

[ ISSN : 2689-1565 ]

Abstract
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Received: 13-Mar-2026

Accepted: 07-Apr-2025

Published: 08-Apr-2025

Research Article | Volume 5 - Issue 1 | Article DOI :

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Hyunju Kim1, Oyoung Kwon2, Jooyoung Lee2, Siyeoung Choi3, Hongyao Lin4, Leonardo Ellerma5*, Sungbo Cho6 and In Ho Kim7

1Pig Management and Clinic, South Korea

2MSD Animal Health Korea Co., Ltd, South Korea

3Department of Animal Biotechnology, Dankook University, Cheonan, South Korea

4MSD Animal Health Innovation Pte Ltd, Singapore

5MSD Animal Health (Phils.), Inc, Philippines

6Department of Animal Biotechnology, Dankook University, Republic of Korea

7Smart Animal Bio Institute (SABI), Dankook University, Cheonan, Republic of Korea

Corresponding Author:

Leonardo Ellerma, MSD Animal Health (Phils.), Inc, Philippines, Tel: +639178386170

Keywords

PRRS; NADC34-like virus; PrimePac PRRS; Vertical Transmission; Modified Live Vaccine; Farrow-to-Finish Herd.

Abstract

Porcine Reproductive and Respiratory Syndrome (PRRS) causes major economic losses, and cross-protection of Modified-Live Vaccines (MLV) against emerging heterologous strains remains uncertain. This study reports a field based, longitudinal before after intervention study evaluating the impact of a Lineage 7 PRRS MLV (PrimePac® PRRS) during an acute NADC-34 like PRRS outbreak in a commercial 1200-sow farrow-to-finish farm in South Korea. Following a confirmation of an NADC-34 like PRRSV outbreak, a whole-herd mass vaccination program was implemented using intradermal administration (0.2ml) of PrimePac® PRRS. Reproductive performance indicators (farrowing rate, abortions, stillbirths and mummification), vertical transmission dynamics (PRRSV qPCR testing of processing fluids), and post-weaning health outcomes (nursery and grow-finish morbidity and mortality, piglet viremia by qPCR) were monitored longitudinally before and after vaccination. After implementation of the vaccination program, key breeding-herd performance parameters progressively returned toward pre-outbreak baseline levels. PRRSV became undetectable in the processing fluid samples within one month, indicating rapid interruption of vertical transmission. Improvement in nursery and grow-finish pig performance occurred more gradually, consistent with ongoing virus circulation in a continuous-flow production system. This findings demonstrate that, although complete virus elimination was not achieved, a strategic mass vaccination program using a Lineage 7 PRRS MLV substantially mitigated the reproductive and early-life impacts of an NADC-34 like PRRS outbreak. Vaccination combined with biosecurity measures remains a critical component of integrated PRRS control strategies in farrow-to-finish systems where eradication is difficult.

Citation

Kim H, Kwon O, Lee J, Choi S, Lin H et al, (2026) Field Evaluation of a Lineage 7 PRRS MLV in Mitigating the Impact of Nadc34-Like PRRS Infection in Korean Pig Farm. JSM Vet Med Res 5(1): 9.