A porcine reproductive and respiratory syndrome virus (PRRSV) 1-4-4 L1C variant strain emerged in the United States in October 2020 and has spread widely, causing high production losses.
However, no unequivocal experimental data was available to determine the virulence phenotype of the 1-4-4 L1C variant, said Jianqiang Zhang, Iowa State University, presenting research with weaned pigs at the 2022 Leman Swine conference.
Zhang said that the data on clinical signs, mortality, body temperature, viremia levels and gross lung lesions confirm that the 1-4-4 L1C variant is highly virulent in weaned pigs.
The higher number of contact pigs becoming viremic at two days post contact implies the L1C variant strain may have higher transmissibility than other PRRSV strains, although that still needs to be confirmed.
