Evaluation of Humoral Response and Protective Efficacy of an Inactivated Vaccine Against Peste des Petits Ruminants Virus in Goats

Four goats were inoculated with an inactivated peste des petits ruminants virus (PPRV) vaccine. Three unvaccinated goats were kept as controls. After 36 days, the four goats were revaccinated. The immune response was monitored by virus neutralization test showing that two doses of the vaccine were able to stimulate strong immune response in all the vaccinated animals. The vaccinated goat and the controls were challenged with virulent PPRV intranasally. After PPRV challenge, the three control goats showed fever, viremia and virus excretion through mucosal surfaces, whereas the vaccinated goats were fully protected against PPRV infection and replication.

Development and Preliminary Evaluation of a New Real-Time RT-PCR Assay For Detection of Peste des petits Ruminants Virus Genome

A duplex real-time reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed for a simple and rapid diagnosis of Peste des petits ruminants (PPR). qRT-PCR primers and TaqMan probe were designed on a conserved region of nucleocapsid protein (Np) of PPR virus (PPRV) genome. An in vitro transcript of the target region was constructed and tested to determine analytical sensitivity. Commercial heterologous Armored RNA(®) was used as an internal positive control (IPC) for either RNA isolation or RT-PCR steps. The detection limit of the newly designed duplex real-time RT-PCR (qRT-PCR PPR_Np) was approximately 20 copies/μl with a 95% probability. No amplification signals were recorded when the qRT-PCR PPR_Np was applied to viruses closely related or clinically similar to PPRV- or to PPR-negative blood samples. A preliminary evaluation of the diagnostic performance was carried out by testing a group of 43 clinical specimens collected from distinct geographic areas of Africa and Middle East. qRT-PCR PPR_Np showed higher sensitivity than the conventional gel-based RT-PCR assays, which have been used as reference standards. Internal positive control made it possible to identify the occurrence of 5 false-negative results caused by the amplification failure, thus improving the accuracy of PPRV detection.

Schmallenberg virus in Italy: a retrospective survey in Culicoides stored during the bluetongue Italian surveillance program

Following the first case of Schmallenberg (SBV) in northern Italy in February 2012, virus detection was conducted on midges collected during the national entomological surveillance program for bluetongue (BT). Six cattle farms, within a radius of 50 km from the SBV case, were selected for a 12 month study, aiming to determine when the virus entered the area, if it was capable of overwintering, and the possible role played by each species of the Obsoletus complex in disseminating the infection. A total of 33,724 Culicoides were collected at the six sites between June 2011 and June 2012. Species belonging to the Obsoletus Complex were the most abundant (94.44%) and, within the complex, Culicoides obsoletus was the most prevalent species in the studying area (65.4%). Nearly 7000 Culicoides midges were screened, either in pools or individually, for SBV by real-time RT-PCR. Viral genome was detected in six pools of the Obsoletus complex, collected at three sites between September and November 2011, and in a single parous female of C. obsoletus, collected in May 2012. As a result of the BT surveillance program in Italy it was possible to demonstrate, retrospectively, that SBV has circulated in at least three Italian provinces since early September 2011, nearly 5 months prior and as far as 40 km away from the first detected case. Similarly, the survey confirmed the presence of SBV in the vector population 3 months after the outbreak, following a cold winter during which the blacklight traps failed to catch active adult midges.

Re-emergence of West Nile virus in Italy

In August 2008, West Nile disease re-emerged in Italy. The infection is affecting the North Eastern regions and, as of November 2008, has caused 33 clinical cases and five fatalities in horses. Until now, no deaths have been reported in birds. Mosquitoes, blood, serum and tissue samples, from horses and birds, within and around the outbreak area, have been collected and tested by various methods both serologically and virologically. West Nile virus strains have been isolated from blood samples of one horse and one donkey and from pools of brain, kidneys, heart and spleen of a pigeon and three magpies. When compared to the strain isolated during the 1998 Tuscany outbreak, the 255 bp sequence of the genome region coding for the envelope (E) protein of the isolated WNV strains, exhibited a 98.8% and 100% similarity at nucleotide and amino-acid level respectively.

Field vaccination of sheep with bivalent modified-live vaccine against bluetongue virus serotypes 2 and 9: effect on milk production

In response to complaints of the potential side-effects of the bivalent live-modified vaccine used to control the spread of bluetongue (BT) virus (BTV) serotypes 2 and 9 in Italy, a study was conducted to determine the effects of immunisation on milk production. Thirty-four Comisana cross-bred sheep were vaccinated with the bivalent BTV-2/BTV-9 modified-live vaccine produced by Onderstepoort Biological Products in South Africa; six animals served as unvaccinated controls. All animals were bled twice a week for two months and the presence and titres of BTV in the blood determined. The somatic cell count, pH, fat, protein and lactose content of the milk, as well as the quantity of the milk produced, were also measured. Vaccine virus was isolated from vaccinated animals between day 3 and day 20 post vaccination (pv) with peak titres observed on days 3 and 6 pv for BTV-2 and BTV-9, respectively. Milk production declined in the vaccinated group between days 8 and 14 pv, with the greatest decrease on day 9 pv. No differences were observed in the somatic cell count and pH, or in the milk fat, protein and lactose content.

A study of the ability of a TK-negative and gI/gE-negative pseudorabies virus (PRV) mutant inoculated by different routes to protect pigs against PRV infection

The capacity of a TK-negative (TK-) and gI/gE-negative (gI/gE-) pseudorabies virus (PRV) mutant to protect pigs against Aujeszky's disease carried out by experimental infection with a virulent PRV strain, was tested. There were three groups, each of four susceptible pigs which were inoculated twice by two different schedules. Group 1 received the modified virus by the intradermal (first inoculation)-intramuscular (second inoculation) routes; group 2 was treated by the intranasal (first inoculation)-intramuscular (second inoculation) routes. The third group was left untreated as the control. All of the pigs were challenged intranasally with a virulent PRV strain and they were subsequently injected with dexamethasone. Two pigs in each group were necropsied on days 5 and 15 after dexamethasone inoculation. The challenge exposure resulted in mild clinical signs, increase in growth and a shorter period of virus shedding in vaccinated pigs, whereas the control group showed severe signs of Aujeszky's disease. No difference in the titre of the virulent virus which was excreted by pigs of all three groups, was observed and all animals seroconverted. Both the mutant strain and the wild-type virus established a latent infection although only the latter was reactivated and shed. Slight lesions were observed in target tissues of the vaccinated animals and no significant differences were detected between the two inoculation schedules.