Prevalence of and carcass condemnation from maedi-visna,paratuberculosis and caseous lymphadenitis in culled sheep from Quebec,Canada

We determined the prevalence of lung and mammary gland lesions associated with maedi-visna (MV) infection, the prevalence of paratuberculosis (PTB), and the prevalence and lesions distribution of caseous lymphadenitis (CL) in culled sheep. Total of 451 ewes and 34 rams were selected randomly from two slaughterhouses in Quebec, Canada. MV serostatus was determined by recombinant ELISA test. PTB diagnosis was based on characteristic histological lesions in the terminal ileum, ileocecal lymph node and/or ileocecal valve and CL by gross detection of abscesses and isolation of Corynebacterium pseudotuberculosis. Seroprevalence of MV was 44% (95% CI: 40, 48). Seropositivity increased with age and was higher in ewes than in rams. The percentages of lung and mammary gland lesions in seropositive sheep were 14 and 40%, respectively, but mammary gland lesions lack specificity. The prevalence of PTB was 3% (95% CI: 2, 5). PTB increased with age and was lower among sheep with abscesses. The prevalence of CL was >/=21% (95% CI: 17, 24). The most-prevalent site of caseous lymphadenitis lesions was the thoracic cavity. The risk of carcass condemnation was significantly associated with region, body score and abscesses. Only the presence of abscesses was associated with an increase in trimming of carcasses.     

Evaluation of two management procedures for the control of maedi-visna.

Two control programs were evaluated for their efficiency in eradicating the maedi-visna (M-V) virus from a single sheep flock. In both programs, the agar gel immunodiffusion test was used for the detection of M-V infected animals at regular intervals. In program 1, the test and remove program, ewes that were serologically positive for M-V were immediately removed along with their offspring. The prevalence of infected sheep decreased gradually and a seronegative flock was obtained after 30 months of monitoring. Program 2 entailed the removal of replacement ewe lambs at birth prior to the ingestion of colostrum. Maedi-visna antibodies have not been detected in this flock. These results show that under conditions similar to the industry norms, M-V can be expelled. Although the approach of program 1 is more practical for sheep producers, program 2 is more effective because of the earlier development of a M-V seronegative flock. Because of the nature of the humoral response, a longer time period than four years is required to ensure that M-V has been completely eradicated from each flock.     

An enzyme-linked immunosorbent assay for detection of antibodies to maedi-visna virus in sheep. I. A simple technique for production of antigen using sodium dodecyl sulfate treatment.

We report the efficacy of an anionic detergent, sodium dodecyl sulfate (SDS) for preparing maedi-visna antigens for an indirect enzyme-linked immunosorbent assay (i-ELISA). Ovine maedi-visna virus (MVV) pelleted by differential centrifugation followed by liquid chromatography was treated with SDS or one of three lipid solvents: ethyl ether, chloroform or fluorocarbon. The SDS-treated antigen resulted in higher optical density values with positive serum and better discrimination between positive and negative serum samples from specific-pathogen-free (SPF) sheep experimentally inoculated with the virus. Optimal results were obtained when MVV was treated with concentrations of 0.25% and 0.125% of SDS. A viral antigen prepared by centrifugation and treatment of a viral pellet with SDS was also suitable for the i-ELISA. This latter technique may facilitate the production of MVV antigens for use in the i-ELISA.     

Unravelling complexities in human malaria transmission dynamics in Africa through a comprehensive knowledge of vector populations

Malaria transmission dynamics is highly variable throughout Africa: inoculation rates vary from almost null to more than a 1000 infective bites per year, transmission can occur throughout the year or only during a couple of months, and heterogeneities are also observed between years within the same locale. Depending on the area, as much as five different anophelines species can transmit parasites to the human population. Major vectors are Anopheles gambiae, Anopheles arabiensis, Anopheles funestus, Anopheles nili and Anopheles moucheti. They all belong to species complexes or groups of closely related species that are very difficult to set apart on morphological grounds. Recent research on the bionomics, morphology and genetics of these mosquito species and populations produced innovative results. New species were described and straightforward molecular identification tools were implemented. We review here these recent findings and discuss research opportunities in light of recent advances in molecular entomology and genomics.     

An enzyme-linked immunosorbent assay for detection of antibodies to maedi-visna virus in sheep. II. Comparison to conventional agar gel immunodiffusion test.

A study was conducted to compare the indirect enzyme-linked immunosorbent-assay (i-ELISA) test using antigen prepared by a simple technique using sodium dodecyl sulfate (SDS) treatment to the conventional agar gel immunodiffusion test (AGID). Ten specific-pathogen-free (SPF) sheep were inoculated with maedi-visna virus (MVV) and serum antibody titers compared over a period of 14 weeks. All the sheep seroconverted by the i-ELISA compared to 90% by the AGID. The i-ELISA detected antibody at a mean of 2.6 weeks prior to the AGID. In both tests, fluctuations were observed in the serum antibody response of two sheep. The i-ELISA had a specificity of at least 98.8% and an increased relative sensitivity of 15.5% compared to the AGID, based on the analysis of sera from experimental sheep with MVV free status and sera from sheep from various sources. Of the sera from a seronegative flock which had been monitored with the AGID after a "test and remove" eradication program, 10.2% were positive by the i-ELISA. It was concluded that the AGID test may not be adequate to monitor samples for an eradication scheme.     

Evaluation of the ability of canarypox-vectored equine influenza virus vaccines to induce humoral immune responses against canine influenza viruses in dogs

OBJECTIVE: To evaluate canarypox-vectored equine influenza virus (EIV) vaccines expressing hemagglutinins of A/equine/Kentucky/94 (vCP1529) and A2/equine/Ohio /03 (vCP2242) for induction of antibody responses against canine influenza virus (CIV) in dogs. ANIMALS: 35 dogs. PROCEDURES: Dogs were randomly allocated into 4 groups; group 1 (n = 8) and group 2 (9) were inoculated SC on days 0 and 28 with 1.0 mL (approx 10(5.7) TCID(50)) of vCP1529 and vCP2242, respectively. Dogs in group 3 (n = 9) were inoculated twice with 0.25 mL (approx 10(5.7) TCID(50)) of vCP2242 via the transdermal route. The 9 dogs of group 4 were control animals. All dogs were examined for adverse reactions. Sera, collected on days -1, 7, 13, 21, 28, 35, and 42, were tested by hemagglutination inhibition (HI) and virus neutralization (VN) assays for antibodies against CIV antigens A/Canine/FL/43/04-PR and A/Canine/NY/115809/05, respectively. RESULTS: Inoculations were tolerated well. The HI and VN antibodies were detected by 7 days after primary inoculation. Most dogs of groups 1 and 2 and all dogs of group 3 had detectable antibodies by 14 days after initial inoculation. The second inoculation induced an anamnestic response, yielding geometric mean HI titers of 139, 276, and 1,505 and VN titers of 335, 937, and 3,288 by day 42 (14 days after booster inoculation) in groups 1, 2, and 3, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Canarypox-vectored EIV vaccines induce biologically important antibodies and may substantially impact CIV transmission within a community and be of great value in protecting dogs against CIV-induced disease.     

Yield and biomass production by African eggplant (<Emphasis Type="Italic">Solanum aethiopicum</Emphasis>) and sorghum (<Emphasis Type="Italic">Sorghum bicolor</Emphasis>) intercropped with planted Ber (<Emphasis Type="Italic">Ziziphus mauritiana</Emphasis>) in Mali (West Africa)

Methods for introduction of an improved cultivar of Ber tree (Ziziphus mauritiana Lam.) also called Jujube and its management on farms through intercropping with African eggplant (Solanum aethiopicum L.) and sorghum [Sorghum bicolor (L.) Moench] were tested in Sanankoroba, Mali. An experimental plantation was established on-farm with seedlings of the local variety of Ber half of which were grafted in situ with an improved cultivar of Ber called Seb. Crop production, Ber growth and fruit production were assessed over two cropping seasons. Both the improved and local varieties of Ber had no detrimental effect on either eggplant or sorghum, both in terms of yield and nutritional quality. In fact a beneficial effect of trees was found on the performance of both crops (yield and dry matter production) which suggests complementarities in resource use. The high level of fruit production by the improved variety of Ber observed on farms under rain-fed conditions may be a source of additional income and diversification of diet for rural communities in West Africa. Therefore, farmers’ adoption of growing improved Ber varieties in association with food crops may help considerably in improving food security and alleviating poverty in the region.     

Antioxidants, phenolic compounds, and nutritional quality of different strawberry genotypes

Strawberry contains high levels of micronutrients and phytochemical compounds. These exhibit functional roles in plant growth and metabolism and are also essential for the nutritional and organoleptic qualities of the fruit. The aim of the present work was to better characterize the phytochemical and antioxidant profiles of the fruit of nine different genotypes of strawberry, by measuring the total flavonoid, anthocyanin, vitamin C, and folate contents. Cultivar effects on the total antioxidant capacities of strawberries were also tested. In addition, the individual contribution of the main antioxidant compounds was assessed by HPLC separation coupled to an online postcolumn antioxidant detection system. This study showed the important role played by the genetic background on the chemical and antioxidant profiles of strawberry fruits. Significant differences were found between genotypes for the total antioxidant capacity and for all tested classes of compounds. The HPLC analyses confirmed qualitative and quantitative variability in the antioxidant profiles. These studies show that differences exist among cultivars, applicable in dietary studies in human subjects.