Epidemiology and molecular characterization of re-emerged virulent strains of Peste des Petits Ruminants virus among sheep in Kassala State, Eastern Sudan.

Background: Peste des Petits Ruminants (PPR) is a severe contagious viral disease, which mainly affects small ruminants. PPR is caused by a Morbillivirus that belongs to the family Paramyxoviridae. In this study 12 suspected PPR outbreaks among sheep and goats were investigated in four localities in Kassala State, Eastern Sudan, during 2015-2017. The causative agent was confirmed by a Sandwich Enzyme-Linked Immunosorbent Assay (sELISA), and a Reverse Transcription Polymerase Chain Reaction (RT-PCR) targeting a partial sequence of nucleocapsid protein gene (N- gene) and a partial sequence of fusion protein gene (F- gene). Sequencing and phylogenetic analysis were carried out on six N- gene based RT-PCR products selected from two outbreaks occurred on border and inner localities of Kassala State to determine the circulating lineages of PPRV strains. Identity percentages were determined between isolates in this study and previous Sudanese, and other (African and Asian) isolates which clustered along with them.

Results: Out of 30 samples, 22 (73.3%) were positive using sandwich ELISA. From 22 s ELISA positive samples, 17 (77.3%) were positive by Ngene based RT-PCR and only 7(43.8%) out of 16 positive samples by N gene based RT-PCR were positive using Fgene based RT-PCR. The sequencing and phylogenetic analysis confirmed involvement of the lineage IV of PPRV in outbreaks among small ruminants in Kassala State and high identity percentage between our isolates and previous Sudanese and other (African and Asian) isolates.

Conclusions: The present study demonstrates that genetic relationship between PPRV strains circulating in sheep in Kassala State, Eastern Sudan, and PPRV strains characterized as lineage IV in neighboring African countries such as Eretria,Ethiopia, Egypt, and other Asian countries.