Taiwan PRRSV-2 Strains Show Divergent Fever Patterns but Similar Disease Severity in Pigs

Porcine reproductive and respiratory syndrome virus 2 (PRRSV-2), formally classified as Betaarterivirus suid 2, remains one of the most economically damaging pathogens of the global swine industry, and its rapid genetic evolution continues to complicate disease control. In a new study conducted in Taiwan, researchers compared the disease-causing properties of two locally circulating strains of the virus: a lineage 1 (L1) NADC30/34-like recombinant strain designated NPUST-107-844/2018 and a lineage 3 (L3) strain designated SW2018001-YL. The work, published in Frontiers in Veterinary Science, was designed both to characterize pathogenic differences between the two lineages and to evaluate whether either isolate could serve as a reliable basis for an experimental infection model in growing pigs.

Lineage 1 PRRSV-2 has emerged and become increasingly prevalent in North America and parts of Asia in recent years, raising questions about whether these newer viruses behave differently from the older lineages already established in endemic regions. Taiwan provides an informative setting for such a comparison because both L1 NADC30/34-like recombinant viruses and L3 strains circulate in the field. To address these questions, the research team, led by Yi-Fang Lai and corresponding author Hui-Wen Chang of National Taiwan University, together with colleagues at National Pingtung University of Science and Technology, inoculated ten-week-old pigs with either the L1 NPUST-107-844/2018 strain or the L3 SW2018001-YL strain via concurrent intranasal and intramuscular routes.

The experimental design allowed direct, side-by-side comparison of clinical, virological, and immunological outcomes between the two lineage groups under identical conditions. The most striking difference between the two groups emerged during the early post-inoculation period. Pigs infected with the L1 NADC30/34-like recombinant strain developed higher body temperatures and experienced a greater frequency of fever than pigs receiving the L3 strain.

This early febrile response indicates that the recombinant L1 virus provoked a more pronounced acute clinical reaction in the first days after infection. However, when the researchers examined the deeper markers of infection and disease, the two lineages proved remarkably similar. No significant differences were observed between the groups in peak viremia, meaning the maximum levels of virus circulating in the blood were comparable regardless of which strain had been administered.

Lung pathological scores, which quantify the extent of tissue damage in the respiratory tract, likewise did not differ significantly between the L1- and L3-inoculated animals, indicating that the recombinant lineage did not cause measurably greater pulmonary disease under these experimental conditions. The immune response told a similar story of convergence. Plasma cytokine concentrations, used here as indicators of the systemic inflammatory response, showed no significant differences between the two infection groups.

The finding that both strains elicited comparable cytokine profiles suggests that the more intense early fever seen with the L1 virus did not translate into a broadly amplified inflammatory response over the course of infection. Taken together, these results indicate that the Taiwan L1 NADC30/34-like recombinant strain induced a more pronounced early febrile response but produced virological, pulmonary pathological, and systemic cytokine responses comparable to those induced by the Taiwan L3 strain. In practical terms, the two lineages differ in the timing and intensity of their earliest clinical signature, yet they appear functionally equivalent in the key parameters that researchers typically use to gauge PRRSV-2 pathogenicity in experimental settings.

The authors emphasize that these findings highlight the pathogenic diversity of circulating PRRSV-2 strains in Taiwan. Beyond its descriptive value, the study carries implications for future experimental work. The comparable viremia, lung pathology, and cytokine responses produced by both strains suggest that either isolate could support experimental infection studies in growing pigs, providing a foundation for investigations of disease pathogenesis, therapeutic interventions, and vaccine development.

As with any controlled infection study, the findings apply to the specific isolates and conditions tested, and field performance of circulating strains may vary with factors such as host genetics, co-infections, and management practices. Nevertheless, the work offers a clear side-by-side picture of how two genetically distinct PRRSV-2 lineages behave in the same experimental host, and it establishes a documented basis for selecting either the Taiwan L1 recombinant or the L3 strain in future studies aimed at understanding and controlling this persistent swine pathogen.

Subject of Research: Comparative pathogenicity of lineage 1 and lineage 3 PRRSV-2 strains in experimentally infected pigs in Taiwan

Article Title: Comparison of the pathogenicity of a Taiwan lineage 1 NADC30/34-like recombinant and a lineage 3 Betaarterivirus suid 2 in pigs

Article References: Lai, Y.-F., Lin, C.-N., Chiou, M.-T., Chang, Y.-C., & Chang, H.-W. (2026). Comparison of the pathogenicity of a Taiwan lineage 1 NADC30/34-like recombinant and a lineage 3 Betaarterivirus suid 2 in pigs. Frontiers in Veterinary Science, 13, 1969559. https://doi.org/10.3389/fvets.2026.1969559

Image Credits: AI Generated

DOI: 10.3389/fvets.2026.1969559

Keywords: PRRSV-2, Betaarterivirus suid 2, lineage 1, lineage 3, NADC30/34-like recombinant, pathogenicity, Taiwan, swine, cytokines, experimental infection, viremia, veterinary virology