Characterizing...Fusobacterium necrophorum subsp. ...Fusobacterium necrophorum subsp. funduliforme, and Fusobacterium varium in bovine and ovine semen, bovine gut, and vagino-uterine and fetal microbiota using...qPCR

Authors: KILAMA, JUSTINE - North Dakota State University; DAHLEN, CARL - North Dakota State University; ABBASI, MINA - Kansas State University; SHI, XIAORONG - Kansas State University; NAGARAJA, T - Kansas State University; Crouse, Matthew; Cushman, Robert; Snider, Alexandria; MCCARTHY, KACIE - University Of Nebraska; CATON, JOEL - North Dakota State University; AMAT, SAMAT - North Dakota State University

Submitted to: Microbiology Spectrum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/3/2025
Publication Date: 3/24/2025
Citation: Kilama, J., Dahlen, C.R., Abbasi, M., Shi, X., Nagaraja, T.G., Crouse, M.S., Cushman, R.A., Snider, A.P., McCarthy, K.L., Caton, J.S., Amat, S. 2025. Characterizing the prevalence of Fusobacterium necrophorum subsp. necrophorum, Fusobacterium necrophorum subsp. funduliforme, and Fusobacterium varium in bovine and ovine semen, bovine gut, and vagino-uterine and fetal microbiota using targeted culturing and qPCR. Microbiology Spectrum. 13(5). Article e03145-24. https://doi.org/10.1128/spectrum.03145-24.
DOI: https://doi.org/10.1128/spectrum.03145-24

Interpretive Summary: Cattle farmers often struggle with getting their cows pregnant, keeping them healthy during pregnancy, and raising calves that are resistant to diseases like liver abscesses, foot rot, and uterus infections. A certain type of very tiny organisms (bacteria) called Fusobacterium has long been thought to only cause infections in cattle. However, new research using advanced DNA testing methods suggests that these bacteria could be naturally present in the healthy reproductive system and might actually help with cattle fertility. But we still don't know exactly which types of Fusobacterium are present or how much of each type is there, so there’s more to learn. Our current study looked at 3 different sub-types of Fusobacterium found in the reproductive systems of healthy cows and unborn calves as well as semen of bulls and sheep. We found that all these bacteria are found in large numbers not only in healthy cows and bull semen but also in unborn calves. This finding suggests that these Fusobacterium might belong to a natural family of small organisms present in cattle reproductive part called microbiome that may help in the reproductive process, possibly supporting pregnancy rather than only causing harm as previously thought. These findings are important because they challenge the belief that Fusobacterium is always harmful to cattle. If it’s well proven that these bacteria are helpful in improving fertility, then farmers might find new, non-antibiotic ways to keep their cattle healthy and improve breeding success. Understanding how these bacteria work could help scientists develop new methods to strengthen the immune systems of cattle even before they are born, leading to healthier animals and more effective farming. This could also help reduce the need for antibiotics, which is important in fighting the growing problem of antibiotic resistance in both humans and animals.

Technical Abstract: Fusobacterium necrophorum is an important pathogen associated with several infectious diseases in cattle. However, recent sequencing-based studies reported that F. necrophorum maybe positively associated with pregnancy in beef cows and that Fusobacterium is highly abundant in bull seminal microbiota with a potential involvement in reproductive health and fertility. Here, we performed a comprehensive screening to i) determine the prevalence of Fusobacterium necrophorum (subspecies necrophorum [FNN] and funduliforme [FNF]), and Fusobacterium varium (FV) in the reproductive microbiota of cattle and sheep as well as digestive tract ecosystems; ii) explore whether these Fusobacterium spp. colonize calf prenatally. For this, we screened 11 different sample types including bovine and ram semen, bovine vaginal and uterine swabs, and bull fecal samples, as well as samples from 180- and 260-day-old calf fetuses and their respective dams using both quantitative PCR (qPCR; 514 samples) and targeted culturing (499 samples). By qPCR, all the targeted Fusobacterium spp. were detected across all sample types with varying prevalence rates and viability. FNF was highly prevalent in the bull semen (66.7%) and maternal ruminal fluids (87.1%), and its viability were confirmed through culturing. All the targeted Fusobacterium were identified in vaginal and uterine (3.1%-9.4%), and caruncles, fetal fluids, rumen and meconium samples (2.7% - 26.3%) by qPCR but were not isolated by culture method. Overall, our results, for the first time, suggest that F. necrophorum is a commensal member of healthy male reproductive microbiota, and that FNF, FNN and FV are present in bovine vagino-uterine microbiota, and calf intestine prenatally.