Development and validation of a modified TaqMan based real-time PCR assay targeting the lipl32 gene for detection of pathogenic Leptospira in canine urine samples

• Main Authors: Bruno Alonso Miotto, Aline Santana da Hora, Sueli Akemi Taniwaki, Paulo Eduardo Brandão, Marcos Bryan Heinemann, Mitika Kuribayashi Hagiwara
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Microbiologia
• Series: Brazilian Journal of Microbiology
• Subjects: Leptospirosis; Dog; Urine; qPCR; lipl32
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1517-83822018000300584&lng=en&tlng=en

Abstract A modified TaqMan real-time polymerase chain reaction targeting a 138 bp fragment within the lipl32 gene was developed to identify exclusively pathogenic Leptospira spp. in dog urine samples. Thirty-five samples from dogs with suspected clinical leptospirosis and 116 samples from apparently healthy dogs were tested for presence of leptospiral DNA using the TaqMan-based assay. The results were compared with those from a well-established conventional PCR targeting the 16S RNA encoding gene associated with nucleotide sequencing analysis. The overall agreement between the assays was 94.8% (confidence interval [CI] 95% 88-100%). The newly developed assay presented 91.6% (CI 95% 71.5-98.5%) relative sensitivity (22[+] lipl32 PCR/24[+] 16S RNA and sequencing), 100% (CI 95% 96.3-100%) relative specificity and 98.7% accuracy (CI 95% 94.8-100%). The lipl32 assay was able to detect and quantify at least 10 genome equivalents/reaction. DNA extracted from 17 pathogenic Leptospira spp., 8 intermediate/saprophytic strains and 21 different pathogenic microorganisms were also tested using the lipl32 assay, resulting in amplification exclusively for pathogenic leptospiral strains. The results also demonstrated high intra and inter-assay reproducibility (coefficient of variation 1.50 and 1.12, respectively), thereby qualifying the newly developed assay as a highly sensitive, specific and reliable diagnostic tool for leptospiral infection in dogs using urine specimens.