company news about Newborn piglet "killer" strikes! Chinese team reveals for the first time the high pathogenicity of G9P[23] and G11P[7] p

Recently, rotavirus (Porcine Rotavirus A, PoRVA) infection has been on the rise in China's pig populations, especially with frequent diarrhea outbreaks caused by new genotypes such as G9P[23] and G11P[7]. Once infected, newborn piglets have a high mortality rate, a rapid course of disease, and rapid transmission, which seriously threatens the stability of the pig industry. More worryingly, the latest research shows that some G9P[23] strains have shown human gene reassortment characteristics, suggesting a potential zoonotic risk. Research highlights · The two new porcine rotaviruses, G9P[23] and G11P[7], are highly pathogenic to newborn piglets, with a mortality rate of up to 100% after infection. · The virus not only attacks the intestines, but also invades the lungs, causing interstitial pneumonia, breaking through traditional cognition. · The virus causes severe intestinal flora disorders and inflammatory reactions, exacerbating the disease. · The G9P[23] virus has human-pig reassortment and has the potential for cross-species transmission. The public health risk cannot be ignored.

In April 2025, the Zhang Zhendong/Li Xiangdong team from Yangzhou University published the first domestic study on the pathogenicity of G11P[7] in Frontiers in Veterinary Science: 100% of 2-day-old piglets without colostrum died after infection;

Almost at the same time, the Zhao Fenghua team from Beijing reported in Frontiers in Microbiology that the human-pig reassortant G9P[23] "HB05 strain" across 5 provinces was also highly virulent. The combination of the two papers sounded the double alarm of "virulence upgrade + cross-species risk" for porcine rotavirus (PoRV) in China.

This study was the first to place G9P[23] and G11P[7] simultaneously in a 2-3 day-old maternal antibody-free piglet model, systematically evaluating the clinical-pathological-microbiome-lung involvement, filling the virulence gap, and also confirming that the "pig→human→pig" reassortant strain is quietly circulating in the farm.

Introduction

Recently, rotavirus (Porcine Rotavirus A, PoRVA) infection has been on the rise in Chinese pig populations, especially with frequent diarrhea outbreaks caused by new genotypes such as G9P[23] and G11P[7].

Once infected, newborn piglets have high mortality, rapid course of disease, and rapid transmission, which seriously threatens the stability of the pig industry. More worryingly, the latest research shows that some G9P[23] strains have shown characteristics of human gene reassortment, suggesting a potential zoonotic risk.

Research Results

1. Virus isolation and identification:

· Researchers isolated two virus strains, AHBZ2304 (G9P[23]) and AHBZ2303 (G11P[7]), from diarrheal piglets.

· Both strains can replicate efficiently in MA104 cells and show obvious cytopathic effects 24–48 hours after infection.

Figure 1. Biological characteristics of strains AHBZ2303 and AHBZ2304 in MA104 cells.

Figure 2. Clinical signs and viral loads in piglets infected with AHBZ2303 and AHBZ2304.

2. Extremely pathogenic, with alarming mortality:

· Infection in 2-day-old piglets that had not consumed colostrum resulted in diarrhea within 12 hours, and all became ill within 24 hours.

· Almost all infected piglets died within 72 hours, with a mortality rate as high as 100%.

· The virus was widely distributed in the intestines, lungs, and mesenteric lymph nodes, with changes and inflammatory infiltrates in the lungs, suggesting that the virus can cross the gut-lung barrier.

Figure 3. Representative images of macroscopic lesions (A), histopathological lesions (B), and immunohistochemical staining (C) in intestinal and lung sections infected with AHBZ2303 or AHBZ2304.

3. Intestinal Dysbiosis and Inflammatory Storm:

· After infection, beneficial bacteria such as Lactobacillus decreased significantly in the intestinal tract of piglets, while opportunistic pathogens such as Akkermansia increased.

· Inflammatory cytokines such as IL-6, IL-8, and TNF-α increased significantly, triggering an "inflammatory storm" and exacerbating intestinal damage.

Figure 4. Analysis of microbiome changes.

The differences in bacterial abundance at the phylum (A) and genus (B) levels were analyzed. The Venn diagram shows the common and unique bacterial genera in the jejunum and ileum of the control and virus-infected groups (C).

4. Human-pig reassortment of G9P[23] virus:

· In another study, HB05 (G9P[23]) virus was confirmed to be a human-pig reassortment virus, and its NSP3 gene was highly homologous to the human strain.

· The virus was prevalent in many places such as Hebei, Liaoning, and Sichuan. The mortality rate of 3-day-old piglets within 4 days after infection reached 80%, and the pathogenicity was significantly higher than that of previous strains.

Figure 5. Phylogenetic analysis using the maximum likelihood method based on the nucleotide sequences of 11 fragments of strain HB05 and other strains.

Figure 6. Isolation, identification and growth curve of HB05 virus.

Summary

G9P[23] and G11P[7] are no longer just “common diarrhea viruses”, but new killers of piglets with the triple threat of “lightning lethality + lung invasion + human-pig reassortment”; updating vaccine strains and strengthening on-site monitoring and biosafety are urgent!