Peste des petits ruminants in Nigeria: identification and variations of lineage II and lineage IV in sheep and goats

Peste des petits ruminants virus (PPRV) is the aetiologic agent of Peste des petits ruminants (PPR), an important viral disease of sheep and goats. PPR is endemic in Nigeria and leads to social and economic losses. The objective of this study was to determine the prevalence of PPR infection and genetically characterize PPRV strains obtained from sheep and goats in three States of Southeast Nigeria. A total of 285 nasal swab samples collected in 2017­2018 were processed for PPRV genome detection by RT­PCR. Sixty­five (22.81%) of the samples were positive for PPRV. Sequence and phylogenetic analyses revealed that the PPRV belonged to lineages II (11/38, 28.9%) and IV (27/38, 71.1%). The N gene fragment sequence showed a 99.77%­100% and 99.98%­100% identity among the strains of lineages II and IV, respectively. Fourteen amino acid substitutions, previously unreported in PPRV strains from Nigeria, were recorded. This study confirms the circulation of PPRV lineages II and IV in Southeast Nigeria, the dominance of strains belonging to lineage IV in recent years, and their close genetic relationship with those previously reported in other parts of Nigeria and neighboring countries.

Comparison of colorimetric loop-mediated isothermal amplification kit and reverse transcription-polymerase chain reaction in the diagnosis of peste des petits ruminants in sheep and goats in Southeast Nigeria.

BACKGROUND AND AIM: Peste des petits ruminants (PPR) is an acute, extremely contagious transboundary viral disease of small ruminants with severe economic consequences, caused by PPR virus. Cost-effective and rapid diagnosis of the disease is essential for prompt management and control. This study aimed to compare the application of a commercial colorimetric loop-mediated isothermal amplification (cLAMP) kit and reverse transcriptase-polymerase chain reaction (RT-PCR) in the diagnosis of PPR in sheep and goats in Southeast Nigeria. MATERIALS AND METHODS: Nasal swab samples were collected from West African Dwarf sheep and goats showing clinical signs suggestive of PPR (n=80) and those without any clinical signs (n=140) of the disease. The diagnosis was achieved through detection of PPR viral genome in the samples using a cLAMP kit and RT-PCR. cLAMP assay was done directly on nasal swab samples without ribosomal nucleic acid extraction. A set of six primers targeting the matrix gene protein was used for the cLAMP assay. RESULTS: PPR viral genome was detected by both cLAMP and RT-PCR in 51 (63.8%) of the 80 samples from sheep and goats with signs suggestive of PPR while 14 (10%) of those without signs tested positive for PPR by both assay methods. There was a 100% agreement in the cLAMP and RT-PCR results. However, cLAMP was a faster, easier, and less expensive method compared to RT-PCR. CONCLUSION: The cLAMP assay demonstrates the potential for a point of care diagnosis in the field and a valuable diagnostic tool in areas with poor electricity supply as well as in a less equipped diagnostic laboratory. Since the reagents are affordable, cLAMP can be a diagnostic tool of choice in the detection and surveillance of PPR virus in countries with limited resources.