Development of reverse genetics system for small ruminant morbillivirus: Rescuing recombinant virus to express Echinococcus granulosus EG95 antigen.

Peste des petits ruminants and cystic hydatidosis may be simultaneously endemic in a given area. Their pathogens are small ruminant morbillivirus (SRMV) and Echinococcus granulosus (E. granulosus), respectively. The SRMV, formerly called peste-des-petits-ruminants virus (PPRV), is classified into the genus Morbillivirus in the family Paramyxoviridae. This virus is an ideal vaccine vector to deliver immunogenic proteins. In this study, a reverse genetics system was developed to rescue a recombinant SRMV (Nigeria 75/1 strain) expressing E. granulosus EG95 antigen in vitro. The recombinant SRMV, albeit replicating more slowly than its parental virus, could effectively express the EG95 antigen in cells by analyses of Western blot, indirect immunofluorescence and mass spectrometry. An EG95 subunit vaccine has been widely used for prevention of cystic hydatidosis in some areas of China. The EG95-expressing SRMV, if proven to induce effective immune responses against both diseases in a future animal experiment, would become a potential candidate of bivalent vaccine.