Oral and Poster Abstracts

amplification of a primary 490 base pair PCR product. The PCR
products were amplified from RNAs extracted from RVFV field
isolates and vaccine strains, propagated in Vero cell cultures.
Amplification products were not detected when the RT-PCR-based
assay was applied on RNA from other related hemorrhagic fever
viruses including Crimean Congo Hemorrhagic fever; dengue virus;
epizootic hemorrhagic disease virus and total nucleic acid extracts from
uninfected Vero cells. The described RT-PCR-based assay provides a
rapid, sensitive and specific assay for detection of RVFV in cell culture
and should be recommended for inclusion during outbreaks of the
disease among humans and susceptible livestock.
Key words: viral hemorrhagic fevers, RVFV, sRNA, RT-PCR
182 Prevention of Coxiella burnetii Shedding in Intedted Dairy
Herds Using a Monovalent Vaccine Containing Phase-1
Coxiella burnetii
R. Guatteo 1 , F. Beaudeau 1 , A. Joly 2 , D. Remmy 3 , H. Seegers 1
1
National Veterinary School of Nantes, Unit of Animal Health
Management, Nantes, France
2
Union Bretonne des Groupements de Défense Sanitaire, Vannes,
France
3
CEVA Santé Animale, Libourne, France
Objective of study: The main aim of this study was to assess the
efficacy of a monovalent vaccine containing phase I Coxiella burnetii
to prevent Coxiella shedding in susceptible (ie considered as non
infected) dairy cows within infected herds in comparison to a placebo.
Materials and Methods: To reach this goal, 336 dairy cows and
heifers, from 6 infected herds with repeated abortions due to Coxiella
burnetii, were followed up over a one-year period. Before treatment (ie
vaccination or placebo), the status of the cows towards Coxiella
burnetii infection was determined on the basis on PCR results on milk,
vaginal mucus and faeces and serological analysis performed 2 weeks
apart. A cow was considered as susceptible when all PCR and
serological results were negative, and was considered as infected
otherwise. Then, the allocation of treatments was performed randomly
within pregnant and non pregnant cows. After treatment (D0), the
animals were subject to systematic samplings (milk, vaginal mucus and
faeces) on D90, D180, D270 and D360 to detect a putative shedding
using PCR. Moreover, under the assumption that calving period is at
maximum risk of shedding, the same samples were taken within 15
days after calving. An animal was considered as a shedder at a given
time t, if at t, it was found positive-PCR tested at least once among the
taken samples. The effect of treatment on the risk for an animal of
becoming shedder was assessed using survival analysis techniques
(Cox regression model).
Results: Almost all heifers were detected as susceptible before
treatment. When vaccinated while not pregnant, an animal had 0.2
(P