[PMC free article] [PubMed] [CrossRef] [Google Scholar] 39. blood samples every 3 weeks from 11 aborting and 26 nonaborting dairy ewes, 20 nonaborting suckler ewes, and 9 ewe lambs. Individual milk samples were also obtained from lactating females. All serum and milk samples were tested by enzyme-linked immunosorbent assay (ELISA), whereas vaginal swabs were tested by quantitative PCR. We found that some dairy females did not seroconvert despite shedding in their vaginal mucus. Overall, antibody levels in adult females were found to remain stable over time, with exceptions during the mating and lambing periods. Maternal antibodies decreased during the first month after birth. Interestingly, antibody levels in milk were correlated with those in serum. This study provides useful field data that will help improve Q fever surveillance and within-flock management steps. IMPORTANCE Field data are necessary to improve the surveillance, diagnosis, and sanitary management of Q fever in livestock. Here, we provide extensive serological data obtained from serum and milk samples from infected and vaccinated ewes belonging to a naturally infected flock of sheep. We show that antibody levels are stable over time and seropositivity and vaginal shedding are not clearly correlated, whereas antibody levels in milk are strongly correlated with those in serum. Accordingly, we find that antibody levels in bulk tank milk are consistent with the variations observed in the serum of dairy females over time. We report the presence of maternal antibody transmission to ewe lambs and we show that the presence of maternal antibodies at birth does not prevent the development of a serological response to vaccination at the age of 4 months. Finally, we report that adult ewes generally seroconvert after vaccination, including during pregnancy. KEYWORDS: Q fever, ruminant, ELISA, serology, cohort study, zoonosis, maternal antibody INTRODUCTION Q fever is usually a widespread zoonosis caused by (4,C6). In humans, infections range from asymptomatic to severe. The clinical indicators are polymorphic and nonspecific; acute Q fever most often results in a flu-like illness, hepatitis, or pneumonia, whereas chronic Q fever may develop in patients with predisposing factors, with the most severe manifestation being endocarditis (7). The major clinical manifestations of Q fever in ruminants, in contrast, are abortions, stillbirths, and delivery of poor offspring, leading to significant economic losses (1, 3, 4). However, infected ruminants are most often asymptomatic, even while shedding infectious bacteria. Assessing the Q fever status of livestock farms may thus show very challenging (3, 4). PCR assays are commonly used to detect directly in biological materials, such as placentas, genital swabs, feces, or milk samples, and they reveal the presence of ongoing infections associated with bacterial shedding (8). In contrast, serological assays are used to detect specific antibodies, and they reveal any past exposure to the bacterium. They are typically used to perform serosurveys, which are designed to provide epidemiological data on Q fever at a relatively low cost, or to complement the results of direct laboratory tests in order to RU-301 confirm the diagnosis of Q fever abortion at the flock level (3, 4). At an individual level, however, serological responses, bacterial shedding, and clinical indicators are not clearly correlated (4). Overall, despite a few experimental infections RU-301 (9,C11), Q fever pathogenesis is still poorly comprehended. It is necessary to investigate the associations between bacterial shedding and antibody responses within infected flocks to RU-301 improve Q fever diagnosis and monitoring at the farm level. The few longitudinal follow-up studies performed with RU-301 cattle (12,C15), goats (15,C18), or other ruminant species (19) have been particularly valuable in providing descriptive data Rabbit Polyclonal to ACRBP on individual shedding patterns and serological responses. Fewer data exist for sheep (15, 20, 21) than RU-301 for the aforementioned species, despite the fact that sheep are frequently associated with clusters of human Q fever cases (22,C24). The purpose of this study was to provide extensive serological data from an infected flock of sheep. The aims were (i) to describe individual associations between shedding and seropositivity, (ii) to assess the stability of antibodies over time and the responses to vaccination, (iii) to monitor maternal antibodies in ewe lambs, and (iv) to compare serological results from milk and serum samples. RESULTS Samples. A total of 564 blood samples and 235 milk samples were obtained from the 66 females studied, as detailed in Table 1. Additionally, 37 vaginal swabs were collected at the beginning of the study, from.