Safety and efficacy of a Bluetongue inactivated vaccine (serotypes 1 and 4) in sheep.

A new inactivated vaccine against Bluetongue virus (BTV) serotypes 1 and 4, was developed from field isolates. Safety and efficacy of the vaccine were evaluated in sheep by serological monitoring and virus nucleic acid detection after experimental infection of vaccinated animals. Seroconversion was observed in vaccinated animals at day 14 post vaccination (pv) with neutralizing antibody titer of 1.9 and 1.8 for serotypes 1 and 4, respectively. The titer increase significantly after the booster reaching 2.7 and persist one year >1.5 for both serotypes. After challenge with virulent isolates, vireamia was recorded in control animals, as evident by q-PCR with threshold cycles (Ct) ranging from 24 to 31 and peaked at day 10 post challenge, while no vireamia was detected in vaccinated animals. Vaccinated sheep were fully protected against the disease and infection.

In-vitro and in-vivo study of the interference between Rift Valley fever virus (clone 13) and Sheeppox/Limpy Skin disease viruses.

Viral interference is a common occurrence that has been reported in cell culture in many cases. In the present study, viral interference between two capripox viruses (sheeppox SPPV and lumpy skin disease virus LSDV in cattle) with Rift Valley fever virus (RVFV) was investigated in vitro and in their natural hosts, sheep and cattle. A combination of SPPV/RVFV and LSDV/RVFV was used to co-infect susceptible cells and animals to detect potential competition. In-vitro interference was evaluated by estimating viral infectivity and copies of viral RNA by a qPCR during three serial passages in cell cultures, whereas in-vivo interference was assessed through antibody responses to vaccination. When lamb testis primary cells were infected with the mixture of capripox and RVFV, the replication of both SPPV and LSDV was inhibited by RVFV. In animals, SPPV/RVFV or LSDV/RVFV combinations inhibited the replication SPPV and LSDV and the antibody response following vaccination. The combined SPPV/RVFV did not protect sheep after challenging with the virulent strain of SPPV and the LSDV/RVFV did not induce interferon Gamma to LSDV, while immunological response to RVFV remain unaffected. Our goal was to assess this interference response to RVFV/capripoxviruses' coinfection in order to develop effective combined live-attenuated vaccines as a control strategy for RVF and SPP/LSD diseases. Our findings indicated that this approach was not suitable for developing a combined SPPV/LSDV/RVFV vaccine candidate because of interference of replication and the immune response among these viruses.

Safety and immunogenicity of the Rift Valley fever arMP-12 ΔNSm21/384 candidate vaccine in pregnant ewes.

Rift Valley fever (RVF) poses a threat to human and animal health as well as economic losses due to abortion, new-born teratogenic effect and mortality. Safe and effective vaccines are critically needed to prevent the disease in humans and livestock. The objective of this study was to assess safety and immunogenicity of the Rift Valley fever virus (RVFV) arMP-12DNSm21/384 attenuated vaccine in 32 pregnant ewes at different stages of pregnancy including 17 ewes vaccinated during the early stage (G1) of pregnancy (<35 days) and 15 ewes vaccinated during the last two stages (G2) of pregnancy (>35 days). Ewes were monitored for clinical observations, rectal temperature and abortions and lambs were monitored for general health and rectal temperature. Vaccinated ewes and lambs were periodically sampled for their neutralizing antibody response to RVFV vaccination. All ewes were positive for antibody two weeks post-vaccination and 79% of ewes were positive at delivery. None of the 32 ewes aborted during pregnancy and all ewes vaccinated during the G2 stages of pregnancy gave birth to healthy lambs. However, among the 17 ewes vaccinated during the G1 stage of pregnancy, 2 ewes gave birth to 2 lambs with fore limb malformations that died at 1-day of age. One ewe gave birth to 2 punny twins that died at 2 days of age. Another ewe, gave birth to one lamb with a deformed tail that died at 20 days of age. At post-mortem, tissues of dead lambs (spleen, lung, brain and long bone) were negative for RVFV by PCR assay. While the findings did not link the malformed lambs directly to infection by the vaccine virus, these results indicated that pregnant sheep should not be vaccinated with the RVFV arMP-12DNSm21/384 vaccine during the first month of gestation.

Peste des petits ruminants pathogenesis on experimental infected goats by the Moroccan 2015 isolate.

BACKGROUND: Peste des petits ruminants (PPR) is a viral disease of major economic importance on small ruminants. Goats are usually known to be more susceptible to the disease. Infection chronology, virus circulation, and the disease early detection need to be better understood. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of goats using a lineage IV virus, the most dominant in the world originated from Asia. PPRV infection was experimentally induced in 4 six-month-old goats by intra-nasal and intravenous route of cell virus suspension and from infectious mashed tissue. The clinical signs were observed and goats were euthanized at predetermined clinical score level for post-mortem examinations and PPRV detection by RT-PCR. Clinical signs of infection were present, pyrexia, serous-mucopurulent nasal discharges, coughing, diarrhea and asthenia, for both cell virus suspension and infectious mashed tissue. PPRV genome was highly detected in swabs and tissues with clinical signs dominated by pulmonary attack and digestive symptoms secondary. RESULTS: Results of this study indicates that PPRV is an invasive infection in animals that in a short period, less than 10 days, invade all vital organs. On live animals, early diagnostic may be easily done on lacrimal and rectal swabs. CONCLUSION: The experimental PPRV-infection model using the cell virus suspension is suitable for vaccine evaluation as a standard model.