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SHIC-Funded Study Responds to Sapovirus Discovery with Diagnostic Tools

A new variant of porcine sapovirus (SaV) was identified in 2019 and appears to be the first detection of a single porcine SaV infection in piglets with diarrhea in the US. On a farm with SaV, piglet diarrhea during the lactation phase resulted in smaller pigs at weaning, with piglets losing one to two pounds, a severe impediment during this phase. Piglet diarrhea had been an issue on this farm for two years, creating a significant financial cost. A study on SaV funded by the Swine Health Information Center (SHIC) is underway with results expected in August 2020. SHIC funded the study to help understand if SaV, which is included on the Center's Swine Disease Matrix, is an emerging pathogen in the US and to develop necessary diagnostic tools. An abstract of the SaV study with initial observations is now available.

The abstract states porcine SaVs are genetically diverse and widely distributed in pig-producing countries. To date, eight genogroups of porcine SaV have been identified, and genogroup III (GIII) is the predominant type. Most of the eight genogroups of porcine SaV are circulating in the US. In the study, reports on detection of porcine SaVs in pigs at different ages with clinical diarrhea using next-generation sequencing and genetic characterization are included.

All seven cases in the study have porcine SaV GIII strains detected and one pooled case was found to have a porcine SaV GVI strain IA27912-B-2018, per the published abstract. Sequence analysis showed that seven GIII isolates were genetically divergent and formed four different lineages on the trees of complete genome, RdRP, VP1 and VP2. In addition, these seven GIII isolates had three different deletion/insertion patterns in an identified variable region close to the three prime end of VP2. The GVI strain IA27912-B-2018 was closely related to strains previously detected in the US and Japan. A 3-nt deletion in VP1 region of GVI IA27912-B-2018 was identified. The study showed genetically divergent SaVs of different genogroups are co-circulating in pigs in the US.

Abstract authors state future studies comparing the virulence of these different genogroups in pigs are needed to better understand this virus. New diagnostic tools will help to understand the incidence of sapovirus and its contribution to piglet diarrheatic syndromes. Then an additional step could be if surveillance and vaccine development are needed to monitor and control porcine SaVs.

As the world deals with the COVID-19 pandemic, SHIC continues to focus efforts on prevention, preparedness, and response to novel and emerging swine disease for the benefit of US swine health. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. SHIC is funded by America's pork producers to fulfill its mission to protect and enhance the health of the US swine herd. For more information, visit http://www.swinehealth.org or contact Dr. Sundberg at psundberg@swinehealth.org.