Understanding PRRSv diversity at the pig and litter level

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This week, Dr. Mariana Kikuti from the MSHMP team is sharing results from a study using whole genome sequencing to assess PRRSv diversity within and across litters.

Key points

  • Viral diversity within the piglet population is generally small, but higher diversity was found in ORFs 4 and 5a.
  • Within animal consensus changes were observed in a period as short as 2 weeks, which means piglets might be going to the GF sites with different viruses than the ones identified closer to farrowing.
Continue reading “Understanding PRRSv diversity at the pig and litter level”

Can Streptococcus suis genotype predict its pathogenicity?

PhD candidate April Estrada, working with Drs. Gebhart and Marthaler published an open-access article on Streptococcus suis in the Journal of Clinical Microbiology. Streptococcus suis is an older pathogen but its prevalence as well as its virulence have been rising lately. This study investigates if categorizing isolates into serotypes and genotypes could help predict the severity of the disease on the farm.

Continue reading “Can Streptococcus suis genotype predict its pathogenicity?”

Science Page: Geographic distribution and genetic diversity of PCV3 from clinical samples in US swine farms

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

This week, we are sharing a report by Zhen Yang a DVM/MS candidate at the UMN, regarding the Geographic distribution and genetic diversity of PCV3 from clinical samples in US swine farms.

Key Points:

  • PCV3 is widespread in the U.S.
  • Abortion cases in the study had a high rate of PCV3 positivity.
  • PCV3 found in association with lesions in an abortion case suggesting causality.

The study looked at 730 cases from the UMN Veterinary Diagnostic Laboratory with a positive sample for PCV3, received between Feb 2016 and Jan 2018.

Yang PCV3 US location genetic diversity

Out of 22 states, 18 states were PCV3 positive. PCV3 was detected in pigs from all ages.

The positive rate among fetus, piglets, nursery and finishing pigs ranged from 15% to 20%. The PCV3 rate in adults was 35%.

PCV3/PCV2 co-infection rate was 5.2%, and PCV3/PRRSV coͲinfection rate was 7.6%.

In our data, we had 67 abortion cases, and 40% of them were PCV3 positive. In one abortion case investigation, histological lesions were observed in lung tissue of aborted fetus and PCV3 in-situ hybridization showed presence of PCV3 in the lesion.

Seven PCV3 whole genome sequences were obtained. Current PCV3 genomes in the U.S shared over 98% nucleotide identities. U.S strains did not cluster together and were grouped with PCV3 sequences obtained in other countries.