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

Abstract

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.