SHIC-funded Work Identifies First Detection Of Pcv4 In The US

Aug 05, 2024

Porcine circovirus associated disease presents a significant challenge to swine health and pork production globally. Multiple types, including PCV2 and PCV3, have worldwide distribution. Since first being described in 2019, PCV4 has been detected in Asia and Europe but not previously in the US. In a study funded by the Swine Health Information Center, PCV4 was detected for the first time in US clinical samples submitted to the Iowa State University VDL from June to September 2023. Led by Dr. Pablo Pineyro at Iowa State University, this study provides initial insight into the frequency of detection, tissue distribution, and genetic characterization of PCV4 in the US. Further studies to understand PCV4 prevalence as well as its role in coinfection and production losses are warranted to assess its importance and perhaps economic impact in the swine industry.

The study has been published by the journal Nature Scientific Reports and is available at nature.com as well as here.

Objectives of this study included (1) characterizing the detection rate of PCV4 across different sample types from clinical submissions, (2) comparing molecular features of US PCV4 ORF2 sequences to reference strains, (3) characterizing the co-detection rates by direct and indirect methods for PCV2, PCV3, and other endemic viral and bacterial pathogens in PCV4 positive samples, and (4) identifying the tissue distribution and immune cell types which facilitate PCV4 replication by direct detection methods. Overall, PCV4 was detected in 8.6% of samples tested with an average PCR Ct value of 33. Lymphoid tissue had the highest detection rate (18.7% positive) and PCV4 was most commonly identified in nursery to finishing aged pigs displaying respiratory and enteric disease. Co-infection with PCV2, PCV3 and other endemic swine pathogens was frequently observed.

To accurately assess PCV4 tissue distribution, the study utilized 512 porcine lung, feces, spleen, serum, lymphoid tissue, and fetal tissue samples submitted for routine diagnostic investigation to the ISU VDL from June through September 2023. Samples were randomly selected to be representative of those used to evaluate different clinical syndromes. PCV4 was detected in 44 of the 512 samples evaluated (8.6%) with positive results in lung (9%), feces (5%), spleen (9%), serum (10%) and lymphoid tissue (17.2%) but was not detected in fetal samples. PCV4 PCR Ct value ranged from 21.3 to 36.2; the average Ct value for different sample types was not significantly different. Direct detection by in situ hybridization confirmed viral replication in lymph nodes and the lamina propria of the small intestine.

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Video: Evolution of Beef Cattle Farming

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Sustainability emerged as a central theme of the conversation, a word that Wooten acknowledges can mean very different things depending on who you ask. For him, sustainability starts with the soil. Healthy soil produces healthy grass, which supports efficient cattle capable of producing year after year with minimal external inputs. It’s an approach that equally considers vegetation, animal efficiency, and long-term profitability.

That philosophy aligned naturally with Wooten’s involvement in the U.S. Roundtable for Sustainable Beef, where he served as a representative for the Colorado Cattlemen’s Association. The roundtable brings together the entire beef supply chain—from producers to retailers—along with universities, NGOs, and allied industries. Its goal is not regulation, Wooten emphasized, but collaboration, shared learning, and continuous improvement.