Isolation and molecular characterization of peste des petits ruminants’ virus in small ruminants from outbreak cases in Eastern Ethiopia

Abstract

Peste des petits ruminants (PPR) is highly contagious viral disease threatening the health and productivity of small ruminants across Africa and Asia. Despite the wide spread vaccination efforts in Ethiopia, recurrent outbreak continue to occur, with limited molecular data on circulating virus strain, particularly in east Africa. This study aimed to isolate and molecular characterization of PPRV from outbreak cases in small ruminants in eastern part of Ethiopia and evaluate the diagnostic performance of immune-capture ELISA (IC-ELISA), conventional PCR, and real time RT-PCR. Fifty nasal and ocular swab samples were collected from clinically affected sheep and goats in Merti and Dodota district. Samples were analyzed using immune capture enzyme-linked immune sorbent assay (Ic-ELISA), one-step real-time reverse transcription-polymerase chain reaction (RT-PCR), and conventional reverse transcription-polymerase chain reaction (RT-PCR).Virus isolation was performed using Vero dog signaling lymphocyte activation molecule tag (Vero-Dog SLAM tag, VDS-45) cell lines. Selected RT-PCR products underwent sequencing and phylogenetic analysis of the partial N gene. Peste des petits ruminants virus was detected in 70% (35/50) of samples by immune-capture ELISA, 54% (27/50) by one-step real-time reverse transcription-polymerase chain reaction (RT-PCR), and 40% (20/50) by conventional reverse transcription-polymerase chain reaction (RT-PCR).Virus isolation was successful in VDS-45 cell showing characteristic Cytopathic effect (CPE). Real time RT-PCR had the highest diagnostic sensitivity and substantial agreement with conventional PCR (Kappa = 0.72), but only slight agreement with IC-ELISA. Sequencing confirmed that the circulating strain belonged to lineage IV, consistent with other African isolates. Goats were more affected than sheep, and nasal swab had a significantly higher viral load than ocular swabs (P < 0.05). The study confirms the circulation of PPRV lineage IV in eastern Ethiopia and highlights real time RT-PCR as the most diagnostic method. The findings underscore the need for enhanced molecular surveillance, targeted vaccination, and improved outbreak response strategies to mitigate the impact of PPR on smallholder livelihoods.