Efficacy of live Chlamydophila abortus vaccine 1B in protecting mice placentas and foetuses against strains of Chlamydophila pecorum isolated from cases of abortion

The efficacy of Chlamydophila abortus vaccine strain 1B in protecting against two selected Chlamydophila pecorum strains, isolated from an aborted goat (M14) in Morocco and a ewe (AB10) in France, was investigated in a mouse model, by comparing the reduction in number of bacteria in the placentas of vaccinated mice challenged intraperitoneally at 11 days of pregnancy with the reference C. abortus (AB7) and C. pecorum (M14, or AB10) strains, to those of unvaccinated mice. Vaccine 1B was shown to provide effective protection against the field strains of C. pecorum, since it significantly reduced the placental Chlamydophila colonisation. The two C. pecorum strains were not sufficiently abortifacient in mice to use reduction in abortion as a criterion of protection.     

Comparison of electron microscopy and polyacrylamide gel electrophoresis in the diagnosis of avian reovirus and rotavirus infections.

Electron microscopy (EM) and genome electropherotyping by polyacrylamide gel electrophoresis (PAGE) for the detection of avian rotaviruses and reoviruses in intestinal specimens and cell cultures were compared. Fifty-eight field samples of intestine with intestinal contents, referred to as direct specimens, from turkey and chicken flocks located in different regions of California and submitted during 1989 for virus isolation were randomly selected as test samples. Also, 38 field intestinal specimens with suspected viral infection that had been passaged three times in primary chicken embryo kidney (CEK) cell cultures were used in their third passage. The percentage of agreement and the Kappa statistic of positive and negative results between these two tests were calculated. In the comparison, EM was considered the standard test. By statistical analysis, an agreement of 87% was observed in cell-culture samples analyzed by the two virus-detection methods, as contrasted with an agreement of 72% for direct specimens. The analysis of the number of segments and band migration profiles of reference and field virus strains indicated that only reoviruses replicated in CEK cell cultures and mainly rotaviruses were detected by both tests in direct specimens. The Kappa statistic analysis indicated substantial agreement (0.69) between the two tests for CEK samples, with moderate agreement (0.45) for the direct specimens examined.     

Differences in ovary size among olive (Olea europaea L.) cultivars are mainly related to cell number,not to cell size

Differences in mature fruit size among olive cultivars are related to differences in ovary size at bloom, but it is not known whether cell number or size determines the variation in ovary size. In this study we measured cell size and number in equatorial cross-sectional areas of the principal ovary tissues (mesocarp and endocarp) in eight cultivars with very different fruit and ovary size. The results showed that cell number explained most of the differences in ovary size, while cell size was not related to ovary size, except for a weak (R² = 0.33) correlation in the endocarp. Since sink strength is thought to be related to cell number, this finding supports the hypothesis that larger ovaries represent stronger sinks. The implications of greater sink strength with bigger ovaries are discussed. Within cultivars, while the cross-sectional areas of mesocarp and endocarp were similar, cell number was higher in the mesocarp but cell size was smaller compared to the endocarp.     

Safety evaluation of the SAG2 rabies virus mutant in Tunisian dogs and several non-target species.

The safety of the SAG2 rabies virus, a highly attenuated mutant of the SAD strain intended to vaccinate dogs by the oral route, was evaluated in local Tunisian dogs and in five other local species likely to consume vaccine baits. These species were the domestic cat (Felis catus), the jackal (Canis aureus), the jerboa (Jaculus orientalis), the merion (Meriones sp.) and the gerbil (Gerbillus campestris). The vaccine was administered orally to 21 dogs, 11 cats and eight jackals and orally or intramuscularly to 62 wild rodents of the above-mentioned species. Seven dogs, one cat, five jackals all juvenile and with poor health status) and two rodents died for intercurrent causes. The others were observed for 60-180 days. No animal showed any rabies symptom. Seroneutralizing antibodies were observed in all experimental groups, only after vaccination, with the highest rate being observed in jackals and rodents. The rabies virus was detected in the oral cavity of three cats 6 h after oral instillation, but was not isolated later either in saliva or in salivary glands. Tissue samples (brain and salivary glands) from dead or euthanized animals were examined for the rabies virus antigen by a fluorescent antibody test. No rabies antigen was detected. These trials confirm the safety of the SAG2 strain on the Tunisian species already demonstrated by other authors on many other target and non target species.     

Effects of growing region and maturity stages on oil yield and fatty acid composition of coriander (Coriandrum sativum L.) fruit

Changes on oil yield and fatty acid profiles were studied during maturation of coriander (Coriandrum sativum L.) fruits cultivated in Menzel Temime and Oued Beja, Tunisia. Oil and petroselinic acid biosynthesis proceeded at a steady rate up to 16 DAF in Oued Beja and in 33 DAF in Menzel Temime. The first results show that a rapid oil accumulation started at newly formed fruits and continued until their full maturity. During fruit maturation, fatty acid profiles varied significantly among the growing regions and stages of maturity. Petroselinic acid had the highest amount at the 16th and the 33th DAF, in Oued Beja and Menzel Temime, respectively. In Oued Beja, at full maturity, the main fatty acids were petroselinic acid (80.90 ± 9.45%), followed by oleic (14.79 ± 2.25%), palmitic (3.50 ± 0.65%) and stearic (0.49 ± 0.09%) acids. Fatty acid profile of fruits cultivated in Menzel Temime showed that in fully ripe fruit, petroselinic acid is the main compound (80.86 ± 7.23%) followed by oleic (14.83 ± 2.05%), palmitic (3.27 ± 3.12%) and stearic (0.31 ± 0.05%) acids. In both growing region, fruit development resulted mainly in an increase of petroselinic acid and a decrease of palmitic acid. Saturated and polyunsaturated fatty acids decreased significantly and monounsaturated fatty acids increased during maturation of fruit. Oil composition at the first four stages of maturity has a healthy and nutritionally value and the last stages were with important economic and industrial applications. Coriander fruit is potentially an important source of petroselinic which have numerous industrial applications.     

The efficiency of in vitro ovine embryo production using an undefined or a defined maturation medium is determined by the source of the oocyte

In vitro oocyte maturation can be influenced by oocyte source and maturation media composition. The aim of the present study was to compare the efficiency of a defined in vitro maturation medium (TCM199 supplemented with cysteamine and epidermal growth factor; Cys + EGF) with an undefined medium (TCM199 supplemented with follicle-stimulating hormone and follicular fluid; FSH + FF) for in vitro production (IVP) of ovine embryos, using oocytes obtained by laparoscopic ovum pick-up from FSH-stimulated [n=11; 158 cumulus-oocyte complexes (COCs)] and non-stimulated (n=16; 120 COCs) live ewes, as well as abattoir-derived oocytes (170 COCs). The produced blastocysts were vitrified and some of them were transferred to synchronized recipients. The best and the worst final yields of embryo IVP observed in this study were obtained using oocytes from FSH-stimulated ewes matured in FSH + FF (41.3%; 33/80) and in Cys + EGF (19.2%; 15/78) medium, respectively (p<0.01). No significant differences between both media were attained in the blastocyst development rate or in the final yield of embryo IVP using oocytes from non-stimulated ewes or abattoir-derived oocytes. The overall in vivo survival rate of the transferred vitrified blastocysts was 13.1% (8/61), without significant differences between oocyte sources or maturation media. In conclusion, under the experimental conditions of the present study, TCM199 supplemented with cysteamine and EGF is a convenient defined maturation medium for IVP of embryos from oocytes of live non-stimulated ewes or from oocytes of abattoir-derived ovaries. However, the best final yield of embryo IVP observed in this study was attained when oocytes came from FSH-stimulated donors and TCM199 was supplemented with FSH and follicular fluid.     

Spatial distribution and habitat selection of culicoides imicola: The potential vector of bluetongue virus in Tunisia

The increasing threat of vector-borne diseases (VBDs) represents a great challenge to those who manage public and animal health. Determining the spatial distribution of arthropod vector species is an essential step in studying the risk of transmission of a vector-borne pathogen (VBP) and in estimating risk levels of VBD. Risk maps allow better targeting surveillance and help in designing control measures. We aimed to study the geographical distribution of Culicoides imicola, the main competent vector of Bluetongue virus (BTV) in sheep in Tunisia. Fifty-three records covering the whole distribution range of C.imicola in Tunisia were obtained during a 2-year field entomological survey (August 2017 – January 2018 and August 2018 – January 2019). The ecological niche of C. imicola is described using ecological-niche factor analysis (ENFA) and Mahalanobis distances factor analysis (MADIFA). An environmental suitability map (ESM) was developed by MaxEnt software to map the optimal habitat under the current climate background. The MaxEnt model was highly accurate with a statistically significant area under curve (AUC) value of 0.941. The location of the potential distribution of C. imicola is predicted in specified regions of Tunisia. Our findings can be applied in various ways such as surveillance and control program of BTV in Tunisia.