Molecular Detection of Abortifacient Zoonotic Bacteria and Placental Gene-Expression Alterations in Ruminants

Abstract

Background: Abortions occurring in cattle, sheep, and goats cause substantial reproductive loss in veterinary obstetrics and pose a significant zoonotic threat to public health. Placental pathogens, such as Brucella spp., Chlamydia abortus, Coxiella burnetii, and Listeria monocytogenes, target placental tissue during infection and trigger inflammatory pathways that impair trophoblast function. Although the infection-associated modulation of placental gene expression is known, the precise mechanisms responsible for the infection-associated loss of pregnancy are unknown. Aim: This study sought to determine the presence of key abortifacient zoonotic pathogens using real-time polymerase chain reaction (RT-PCR) and evaluate the association between pathogen presence and placental gene-expression changes of selected pro-inflammatory, anti-inflammatory, and trophoblast-integrity genes in ruminant species that were aborted. Methods: Placental cotyledon and uterine discharge samples were collected from cattle, sheep, and goats with a recent history of abortion. Pathogen detection was performed using RT-PCR targeting bcsp31, ompA, IS1111, and hlyA, while placental gene expression (IL1B, IL6, ILTNF-α, IL10, VEGFA, and PLAC1) was quantified using SYBR Green RT-qPCR normalized to GAPDH. Gene expression results were calculated using the Δ Δ Ct method and correlated with the positive samples for the pathogens. Results: Infection was confirmed in a high proportion of the cases of abortion by RT-PCR, and Brucella spp. and C. abortus were the most commonly seen. Significant upregulation of IL1B, IL6, and ILTNF- -α in the infected placentas, and IL10 was downregulated, indicating a strong inflammatory shift. There was considerable suppression of VEGFA and PLAC1, which means that there was placental vascularization and impairment of trophoblast stability. These changes in molecules were strongly connected with the presence of the pathogens, which showed their involvement in the abortion. Conclusion: Certain disruptions in placental gene expression caused by abortifacient zoonotic pathogens are responsible for the loss of pregnancies. Profiling these molecules with RT-PCR provides a useful means for identifying infectious abortion and evaluating its public health significance. Article History:Received June 20, 2026Revised August 02, 2026Accepted: August 10, 2026Published: September 06, 2026