Sheep with scrapie and mastitis transmit infectious prions through the milk.

Prions are misfolded proteins that are infectious and naturally transmitted, causing a fatal neurological disease in humans and animals. Prion shedding routes have been shown to be modified by inflammation in excretory organs, such as the kidney. Here, we show that sheep with scrapie and lentiviral mastitis secrete prions into the milk and infect nearly 90% of naïve suckling lambs. Thus, lentiviruses may enhance prion transmission, conceivably sustaining prion infections in flocks for generations. This study also indicates a risk of prion spread to sheep and potentially to other animals through dietary exposure to pooled sheep milk or milk products.

Small ruminant lentivirus genotype E is widespread in Sarda goat.

The highly divergent SRLV genotype E has recently been characterized in Italy as a low pathogenic caprine lentivirus in the Roccaverano breed. The availability of a genotype specific diagnostic test based on a comparative assay, using a combination of genotype specific recombinant antigens allows a wide serosurvey in other goat populations. The island of Sardinia still has the highest small ruminant population of any Italian region and crossbreeding has been limited to goats, mainly with the Maltese breed. A serological survey was carried out on sheep flocks and goat herds, using individual sera as well as a bulk milk-adapted procedure. Genotype E was identified in more than 50% of goat herds and none of the sheep flocks thus supporting the idea that this genotype is specifically associated with the goat species. The full-length proviral sequence of a Sardinian isolate revealed and confirmed the deletion of dUTPase subunit and the absence of both vpr gene and the 71bp repeat of the LTR. Genetic similarity of this isolate with the prototype strain Roccaverano was not more than 84%, supporting the designation of two subtypes within genotype E. Nevertheless, in vitro properties of the Sardinian strain were different from those of the Roccaverano strain in terms of ability to infect synovial membrane and produce syncitia. Remarkable differences in the HV1 and HV2 of the env gene were recorded, with the Sardinian isolate displaying sequence motif more similar to arthritic strains. Data presented suggest diffusion of genotype E is wider than previously thought.

Detection of pathogens in ovine and caprine abortion samples from Sardinia, Italy, by PCR.

During 2003-2005, 399 abortion samples (315 fetuses and 84 placentae) were collected from 107 ovine and caprine farms in northern Sardinia. Tissues from aborted fetuses and placentae were examined by PCR assay to detect DNA from Coxiella burnetii, Chlamydophila abortus, Salmonella enterica Serovar abortusovis, Toxoplasma gondii, and Neospora caninum. The DNA from at least 1 of these 5 infectious agents was amplified in 41% of ovine fetuses, while only 17% of the caprine fetuses yielded a positive amplification result for at least 1 of the 5 agents. Out of a total of 366 ovine aborted samples, T. gondii DNA was detected most frequently (18.1% of fetuses and 13.1% of placentae), followed by S. abortusovis (13% of fetuses and 14.4% of placentae), C. burnetii (10.9% of fetuses, of 9.2% placentae), C. abortus (2.4% of fetuses, 6.5% of placentae), and N. caninum (2% of placentae). In 33 fetuses and 9 placentae, the simultaneous presence of pathogens with different associations was detected. Out of a total of 31 caprine aborted samples, T. gondii was detected most frequently (13% of fetuses and 25% of placentae), followed by C. abortus (12.5% of placentae), C. burnetii (12.5% of placentae), and N. caninum (8.6%).

Geographic information systems: a useful tool to approach African swine fever surveillance management of wild pig populations.

The epidemiological surveillance of African swine fever in wild pig populations requires the previous collection of numerous samples of biological materials for virological and serological testing from each animal that has been killed during the hunting season. The number of samples needs to demonstrate the absence of the disease at a prevalence level of 5% (and confidence level of 95%) in the area subject observed. Since the typology of the territory suitable for maintaining wild pig populations and the precise location can be identified, it is possible to pinpoint specific areas within Sardinia where organised sampling is undertaken. The results from tests are used to estimate the prevalence of the disease in the wild pig population in the place of origin. Areas were identified using the geographic information system technology with support from maps in the field. The correct localisation of seropositivity has led to the redefinition of high-risk areas for African swine fever. Results from the outbreaks and the surveillance of the wild pig population has confirmed the decreasing role of the wild boar in maintaining the disease.

Use of geographic information systems technology in the epidemiological surveillance of African swine fever.

Geographic information systems (GIS) proved to be very useful during the last two outbreaks of African swine fever in Sardinia and enabled comprehensive the implementation and organisation of the epidemic surveillance system. The knowledge of the precise location of the centre of infection made it possible to characterise all centres of infection and led to the mapping of possible routes of origin and spread of the virus from one case to another. GIS provided valuable and essential information to determine areas that required restrictions and offered an effective model of synergy between epidemiological data and legislative requirements during the epidemic.

Study of the safety and efficacy of a recombinant vaccine for bluetongue virus serotype 2.

A total of 7 cows, 10 sheep and 10 goats were vaccinated subcutaneously with 5 ml of a recombinant vaccine consisting of synthetic virions containing the four principal proteins (VP2, VP3, VP5 and VP7) of bluetongue virus serotype 2 (BTV-2). The same number of animals and species were vaccinated with 2.5 ml (the normal vaccination dose) and 2 cows, 2 sheep and 2 goats were inoculated with a placebo and the adjuvant added to the vaccine. Animals vaccinated with the normal dose received a booster 14 days after the first injection and 8 sheep a third vaccination 4 months after the second inoculation. One month after the third vaccination, the 8 sheep and another 4 that had never come into contact with the virus were challenged with 1 ml of 10(5.8) TCID(50) of a BTV-2 Italian field isolate. All animals showed competitive enzyme-linked immunosorbent assay (c-ELISA) antibodies starting 14 days following the first vaccination. Conversely, no animal demonstrated neutralising antibodies to BTV-2 after vaccination. Fever (>40 degrees C) was observed in 6 vaccinated animals and 2 controls between 8 and 13 days post challenge. The virus was isolated from all animals from the 7th day post challenge. There was no significant difference in the blood chemical parameters tested and no significant interaction was found in the trial group.