Shi Hongfei, Lv Tingting, Zhang Zhengtian, Zhai Hongyue, Wang Li, Ji Shidong, Li Dandan, Yao Lunguang
Henan Key Laboratory of Insect Biology in Funiu Mountain, Henan Province Engineering Research Center of Insect Bioreactor, China-UK International Joint Laboratory for Insect Biology of Henan Province, Nanyang Normal University, Nanyang, PR China.
BMC Vet Res. 2025 Jul 12;21(1):460. doi: 10.1186/s12917-025-04917-3.
In central China, free-range cattle face high risks of exposure to arthropod-borne pathogens like Bovine ephemeral fever virus (BEFV) and 'Candidatus Mycoplasma haemobos' ('Ca. M. haemobos'). Despite their co-endemicity, the role of ticks in BEFV transmission remains unexplored in China, and potential interactions between these pathogens are unknown. This study aimed to (1) investigate the coinfection of BEFV and 'Ca. M. haemobos' in cattle fever outbreaks, (2) evaluate ticks as potential vectors for both pathogens, and (3) characterize viral evolution.
From August to September 2024, blood, tissue, and tick samples were collected from 61 clinically ill cattle (Group 1) and 17 asymptomatic cattle (Group 2) in the same farms, and 18 healthy cattle (Group 3) in six different farms in central China. Ticks were morphologically and molecularly identified. Pathogens were screened by PCR and sequencing analysis. The serum was subjected to virus neutralization assays. In Group 1, BEFV and 'Ca. M. haemobos' were detected in 86.9% and 67.2% of cattle, respectively, with a coinfection rate of 44.3% (27/61). All deceased cattle (8/8) tested positive for BEFV, and 75% were coinfected. Ticks (Haemaphysalis longicornis, Rhipicephalus microplus, Rhipicephalus sanguineus sensu lato) from Group 1 carried BEFV (46.8%, 11.3%, and 18.8%) and 'Ca. M. haemobos' (34.8%, 35.5%, and 31.3%). Engorged H. longicornis exhibited higher BEFV infection rates than unfed ticks (p < 0.001). In Group 2, the two pathogens were only detected in H. longicornis ticks with positive rates significantly lower than those in ticks in Group 1 (p < 0.05). In Group 3, all samples were negative for the pathogens. Moreover, the BEFV strain HN2437 in this study showed divergence from global lineages, suggesting unique evolution. Neutralizing antibodies against BEFV were only found in cattle in Group 1 with the seroprevalence rate of 26.2% (16/61).
This study provides the first evidence of ticks as potential BEFV carriers in China and highlights that coinfection with 'Ca. M. haemobos' may be a factor in severe disease outcomes. The distinct evolutionary profile of HN2437 strain underscores the need for evaluating effect of vaccine in use.
在中国中部，放养的牛面临着接触节肢动物传播病原体的高风险，如牛暂时热病毒（BEFV）和“嗜血性支原体（暂定种）”（“Ca. M. haemobos”）。尽管它们共同流行，但在中国，蜱在BEFV传播中的作用仍未得到探索，并且这些病原体之间的潜在相互作用也不清楚。本研究旨在：（1）调查牛发热疫情中BEFV和“Ca. M. haemobos”的合并感染情况；（2）评估蜱作为这两种病原体潜在传播媒介的可能性；（3）对病毒进化进行特征分析。
2024年8月至9月，从中国中部同一养殖场的61头临床患病牛（第1组）和17头无症状牛（第2组）以及六个不同养殖场的18头健康牛（第3组）采集血液、组织和蜱样本。对蜱进行形态学和分子鉴定。通过PCR和测序分析筛查病原体。对血清进行病毒中和试验。在第1组中，分别在86.9%和67.2%的牛中检测到BEFV和“Ca. M. haemobos”，合并感染率为44.3%（27/61）。所有死亡牛（8/8）的BEFV检测呈阳性，75%为合并感染。第1组的蜱（长角血蜱、微小牛蜱、血红扇头蜱（狭义））携带BEFV（46.8%、11.3%和18.8%）和“Ca. M. haemobos”（34.8%、35.5%和31.3%）。饱血的长角血蜱的BEFV感染率高于未进食的蜱（p < 0.001）。在第2组中，仅在长角血蜱中检测到这两种病原体，阳性率显著低于第1组的蜱（p < 0.05）。在第3组中，所有样本的病原体检测均为阴性。此外，本研究中的BEFV毒株HN2437与全球谱系存在差异，表明其独特的进化特征。仅在第1组的牛中发现了针对BEFV的中和抗体，血清阳性率为26.2%（16/61）。
本研究首次提供了蜱作为中国潜在BEFV携带者的证据，并强调与“Ca. M. haemobos”的合并感染可能是导致严重疾病结果的一个因素。HN2437毒株独特的进化特征突出了评估现有疫苗效果的必要性。
