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

Abstract 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

Development and field application of a new combined vaccine against Peste des Petits Ruminants and Sheep Pox

A combined vaccine against Peste des Petits Ruminants (PPR) and Sheep/Goat Pox (SGP) was developed and applied in the field, using a new association of vaccine strains: PPR Nigeria 75 strain with a titre of 104.1 TCID50 and Sheep Pox Romania strain with a titre of 104.0 TCID50. Safety and efficacy were evaluated on goats and sheep in comparison with monovalent PPR and SGP vaccines. Goats were challenged by PPR virulent strain and sheep by SP virulent strain. The result shows that the combined PPR/SGP vaccine confers a good protection against both PPR and SGP infection with no significant difference with monovalent vaccines. The combined vaccine was used in the field on sheep flocks and good sero-conversion was detected for both diseases as soon as 14 days post vaccination

Enhancement of glass transition temperature for poly(methyl methacrylate) by salt

We investigated the effects of two metal salts, lithium trifluoromethanesulfonate (LiCF_3SO_3) and lithium bromide (LiBr), on the glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA). Both LiCF_3SO_3 and LiBr greatly enhanced the T_g of PMMA under dry conditions. However, once the sample films were exposed to humidity, the PMMA containing LiCF_3SO_3 absorbed a large amount of water, which acts as a plasticizer. As a result, the T_g shifted to a lower temperature, which limits the utility of this polymer in industrial applications. In contrast, the T_g of PMMA containing LiBr was minimally affected by the absorption of water. This phenomenon can be explained by the ion–dipole interactions with the small number of dissociated lithium cations