Comparative genomic and phenotypic analysis of human- and dairy cattle -derived Streptococcus agalactiae reveals potential cross-species infection capability.
4 affiliations
- 1Institute of Feed Research, Chinese Academy of Agricultural Sciences, No. 12 South Street, Haidian District, Beijing, 100000, China.
- 2Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, 100000, China.
- 3Institute of Feed Research, Chinese Academy of Agricultural Sciences, No. 12 South Street, Haidian District, Beijing, 100000, China. [email protected].
- 4Institute of Feed Research, Chinese Academy of Agricultural Sciences, No. 12 South Street, Haidian District, Beijing, 100000, China. [email protected].
Abstract
Background
Streptococcus agalactiae is an opportunistic Gram-positive pathogen that can infect humans, dairy cattle, and other animals, posing a potential zoonotic risk. In this study, whole-genome sequencing was performed on 40 GBS strains isolated from dairy cows. The results showed high homology among strains collected from the same farm. Based on these findings, two representative dairy cattle-derived strains and one human-derived strain were selected for comparative whole-genome analysis to identify differences in antibiotic resistance and virulence genes. Additionally, we characterized the antibiotic resistance phenotypes, hemolytic phenotypes, invasion capacity, and the levels of oxidative stress markers and inflammatory factors in bovine mammary epithelial cells (BMECs) during infection for all three strains.Result
The three strains HB27, HB31, and RW exhibited close phylogenetic relationships. All showed strong resistance to sulfonamide and aminoglycoside antibiotics but remained susceptible to cephalosporins, quinolones, and macrolides. The mefA gene was present in RW but absent in HB27 and HB31. RW exhibited higher hemolytic activity and cylE mRNA expression levels than HB27 and HB31, and the pilA and pilB genes were also present only in RW. HB31 demonstrated significantly faster invasion rates than HB27 and RW before the 2‑h invasion time point. The effects of the three strains on antioxidant markers and the protein and mRNA expression of inflammatory factors in BMECs were consistent, indicating that the human-derived S. agalactiae possesses the capacity to infect BMECs.Conclusion
Although human- and dairy cattle-derived GBS differ in virulence-associated genes and hemolytic activity, the human strain invades BMECs in vitro and induces host responses similar to those of dairy cattle strains. These findings suggest that human-derived GBS may have the potential for cross-species infection. To date, most studies on human- and dairy cattle-derived GBS have focused primarily on epidemiology. Even when addressing whether GBS is a zoonotic pathogen, direct evidence of cross-species transmission mechanisms remains limited. This study provides in vitro evidence that human-derived GBS can directly infect BMECs. However, whether cross-species transmission between human- and dairy cattle-derived GBS requires repeated exposure or can occur following a single exposure requires further investigation.
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BibTeX
@article{jiang2026comparative,
title = {{Comparative genomic and phenotypic analysis of human- and dairy cattle -derived Streptococcus agalactiae reveals potential cross-species infection capability.}},
author = {Lin Jiang and Tingting Sun and Jing Liu and Xinyu Wang and Jin Zhou and Xiubo Li and Fei Xu},
journal = {BMC microbiology},
year = {2026},
month = jul,
doi = {10.1186/s12866-026-05211-4},
url = {https://europepmc.org/article/MED/42919174},
note = {CC BY-NC-ND},
}
RIS
TY - JOUR
TI - Comparative genomic and phenotypic analysis of human- and dairy cattle -derived Streptococcus agalactiae reveals potential cross-species infection capability.
AU - Lin Jiang
AU - Tingting Sun
AU - Jing Liu
AU - Xinyu Wang
AU - Jin Zhou
AU - Xiubo Li
AU - Fei Xu
PY - 2026
DA - 2026/07/01
JO - BMC microbiology
DO - 10.1186/s12866-026-05211-4
UR - https://europepmc.org/article/MED/42919174
AB - Background Streptococcus agalactiae is an opportunistic Gram-positive pathogen that can infect humans, dairy cattle, and other animals, posing a potential zoonotic risk. In this study, whole-genome sequencing was performed on 40 GBS strains isolated from dairy cows. The results showed high homology among strains collected from the same farm. Based on these findings, two representative dairy cattle-derived strains and one human-derived strain were selected for comparative whole-genome analysis to identify differences in antibiotic resistance and virulence genes. Additionally, we characterized the antibiotic resistance phenotypes, hemolytic phenotypes, invasion capacity, and the levels of oxidative stress markers and inflammatory factors in bovine mammary epithelial cells (BMECs) during infection for all three strains.Result The three strains HB27, HB31, and RW exhibited close phylogenetic relationships. All showed strong resistance to sulfonamide and aminoglycoside antibiotics but remained susceptible to cephalosporins, quinolones, and macrolides. The mefA gene was present in RW but absent in HB27 and HB31. RW exhibited higher hemolytic activity and cylE mRNA expression levels than HB27 and HB31, and the pilA and pilB genes were also present only in RW. HB31 demonstrated significantly faster invasion rates than HB27 and RW before the 2‑h invasion time point. The effects of the three strains on antioxidant markers and the protein and mRNA expression of inflammatory factors in BMECs were consistent, indicating that the human-derived S. agalactiae possesses the capacity to infect BMECs.Conclusion Although human- and dairy cattle-derived GBS differ in virulence-associated genes and hemolytic activity, the human strain invades BMECs in vitro and induces host responses similar to those of dairy cattle strains. These findings suggest that human-derived GBS may have the potential for cross-species infection. To date, most studies on human- and dairy cattle-derived GBS have focused primarily on epidemiology. Even when addressing whether GBS is a zoonotic pathogen, direct evidence of cross-species transmission mechanisms remains limited. This study provides in vitro evidence that human-derived GBS can directly infect BMECs. However, whether cross-species transmission between human- and dairy cattle-derived GBS requires repeated exposure or can occur following a single exposure requires further investigation.
SN - 1471-2180
ER -