会社のニュース The latest epidemiological survey of swine diarrhea virus in China shows that PEDV remains the "number one killer," with

On January 16, 2026, a joint research team from Jilin University and Xinjiang Tiankang Biopharmaceutical published their latest research on diarrhea-related viruses in Chinese swine herds in *Pathogen Genetics*, a journal under the *Virulence* umbrella. This study systematically revealed the spatiotemporal distribution patterns and molecular evolutionary characteristics of four major diarrhea viruses (PEDV, PoRVA, TGEV, and PDCoV) between 2022 and 2024, providing important scientific evidence for the precise prevention and control of viral diarrhea in swine in my country and for vaccine development.

Research Highlights

* PEDV is absolutely dominant: with a positivity rate as high as 50.90% and a farm positivity rate of 66.67%, it is the primary pathogen causing swine diarrhea.

* PoRVA poses a significant threat: with a positivity rate of 33.80%, and its infection rate has surpassed that of PEDV in six provinces including Henan and Gansu, requiring close monitoring of its epidemic situation.

• Significant seasonal and regional variations: PEDV is prevalent in spring and winter, while PoRVA surges in the fourth quarter. Geographically, PEDV infection rates are generally higher in southern provinces, while PoRVA is more active in Central and Northwest China.

• Widespread co-infection: The co-infection rate of PEDV and PoRVA is as high as 19.05%, significantly increasing clinical complexity and the difficulty of prevention and control.

• Reveals key antigenic variation characteristics: For the first time, the neutralizing epitope variation pattern of the PEDV S protein in the current circulating strain has been elucidated: the SS2 and SS6 epitopes are highly conserved and are ideal targets for broad-spectrum vaccine design; while the COE and 2C10 regions show frequent variations, suggesting a significant risk of viral immune escape and making them a key focus for vaccine updates.

Between 2022 and 2024, the research team collected 1343 diarrheal samples (small intestinal tissue, intestinal contents, and feces) from 84 pig farms in 20 provinces of China. Using quadruple real-time quantitative PCR, they systematically analyzed the infection status of PEDV, PoRVA, TGEV, and PDCoV, and sequenced and performed evolutionary analysis on the S gene of PEDV and the VP7 gene of PoRVA.

Introduction

Porcine viral diarrhea is one of the major infectious diseases facing the global pig industry, primarily affecting piglets and causing severe diarrhea, vomiting, and dehydration. Mortality rates in 3-day-old piglets can reach as high as 70%–100%.

In my country, porcine viral diarrhea has long been endemic, and its epidemic pattern has continued to change in recent years. The succession of dominant pathogens, spatiotemporal differences, and ongoing molecular evolution of different viruses (such as PEDV and PoRVA) pose ongoing challenges to precise prevention and control. Therefore, systematically elucidating the epidemiological patterns and molecular characteristics of the current major diarrhea viruses is of urgent practical significance for updating prevention and control strategies and guiding vaccine development.

Research Results

1. PEDV remains the dominant pathogen causing swine diarrhea, with mixed infections being a prominent issue.

The research team conducted quadruple RT-qPCR testing on 1343 samples. The results showed a PEDV positivity rate as high as 50.90% (66.67% of pig farms were infected); the PoRVA positivity rate was 33.80%. In contrast, the detection rates of TGEV (3.10%) and PDCoV (6.00%) were lower. Notably, the mixed infection rate of PEDV and PoRVA was as high as 19.05%, indicating a significantly increased complexity in swine diarrhea control.

Figure 1. Epidemiological status of diarrhea-associated viruses.

Table 1. Epidemiology of Swine Diarrhea-Related Viruses in Various Provinces of China.

2. Significant Regional Differences in Epidemiology Between North and South China.

Geographic visualization analysis shows that in this survey, PEDV prevalence was significantly higher in South China (Guangdong, Guangxi, and Yunnan), with positivity rates exceeding 80%; PoRVA formed high-prevalence areas in Henan, Xinjiang, and Zhejiang, with positivity rates exceeding 60%. PDCoV was mainly detected in Jiangxi and Henan, followed by Gansu and Liaoning; TGEV was only sporadically detected in four provinces, remaining at a low prevalence level overall.

Figure 2. Geographical visualization of the infection status of four diarrhea-related viruses in different regions of China.

3. Winter and spring are the main peak seasons for the spread of porcine diarrhea viruses.

Quarterly surveillance from 2022 to 2024 showed that PEDV was detectable year-round, but the positivity rates in Q1, Q2, and Q4 were significantly higher than in summer (Q3); PoRVA showed a clear seasonal peak, with the positivity rate rising to 57%–65% in Q4 each year. PDCoV was not detected in 2022, but the detection rate increased significantly from 2023 onwards; TGEV was detected again starting in Q4 of 2023, suggesting a potential resurgence trend.

Figure 3. Infection status and trends of four diarrhea-associated viruses in different regions of China from 2022 to 2024.

4. PEDV gene evolution is dominated by GIIa and GIIc.

Sequencing analysis of 21 PEDV S gene strains showed that GIIa accounted for 52.38%, GIIc for 42.86%, and GIIb for 4.76%. No GI group strains were detected in this study. Epitope analysis showed that the neutralizing epitopes of SS2 and SS6 were highly conserved (only one amino acid variation was found), providing potential targets for vaccine design; however, 24 amino acid mutation sites appeared in the COE region, and the 2C10 epitope showed frequent variations, which may be related to viral immune escape.

Figure 4. Phylogenetic tree constructed based on PEDV S gene.

Figure 5. Comparison of amino acid epitopes of PEDV S protein.

5. PoRVA genotypes show significant diversity.

Analysis of the VP7 gene of 16 PoRVA strains identified six genotypes: G1, G3, G4, G5, G9, and G11. G4 (31.25%), G5 (18.75%), and G9 (18.75%) were the predominant genotypes. Epitope analysis showed that, except for G1, the other genotypes exhibited significant variation in the A, B, and C antigen regions, while the E region was relatively conserved. This study further identified three conserved short peptides (aa106–115, 159–170, and 251–259), all located in the VP7 protein loop region, which have research value as potential diagnostic targets and vaccine candidate antigens.

Figure 6. Phylogenetic tree of PoRVA constructed based on the VP7 gene.

Figure 7. Comparison of amino acid epitopes of PoRVA VP7 protein.

Figure 8. Location of the conserved PoRVA peptide in the resolved VP7 structure.

Summary

This study not only updated the epidemiological baseline data of porcine diarrhea virus (PEDV) in China, but also revealed the evolutionary characteristics and antigenic variation patterns of PEDV and PoRVA at the molecular level. The results indicate that current vaccine design should focus on hypervariable regions of PEDV such as COE and 2C10, and explore the potential of conserved PoRVA peptides as broad-spectrum vaccine candidate targets. Simultaneously, the study suggests strengthening monitoring and control efforts during winter and spring and in high-incidence areas, and implementing targeted immunization and biosafety measures.