An overview on the molecular diagnosis of animal leptospirosis

Abstract

The most common presentation of animal leptospirosis is the subclinical and silent chronic form, that can lead to important reproductive disorders. The diagnosis of this chronic form remains a challenge. The aim of the present study is to gather and critically analyse the current information about molecular tools applied to animal leptospirosis diagnosis, particularly the silent chronic presentation of the infection. Regarding clinical specimens, samples from urinary tract were the most used (69/102, 67·7%), while few studies (12/102, 11·8%) investigated samples from reproductive tract. Concerning the molecular methods applied, the most used is still the conventional polymerase chain reaction (PCR) (46/102, 45%), followed by real‐time PCR (38/102, 37·2%). The lipL32 gene is currently the most common target used for Leptospira detection, with 48% of studies applying this genetic marker. From all the studies, only few (21/102, 20·5%) performed gene sequencing. According to the majority of authors, current evidence suggests that lipL32‐PCR is useful for an initial screening for Leptospira DNA detection in animal clinical samples. Posteriorly, if DNA sequencing could be performed on positive lipL32‐PCR samples, we encourage the use of secY gene as a genetic marker. The molecular methods appear as the most important tools for the diagnosis of the chronic silent leptospirosis on domestic animals, reinforcing its evident impact not only on animal reproduction but also on a One Health context.

First detection of Leptospira santarosai in the reproductive track of a boar: A potential threat to swine production and public health

“…It is impossible to know if the animal would have shown any response to a serovar of L. santarosai because the reference diagnostic laboratory, where the MAT was performed, does not use L. santarosai serovars or any characterized local isolates. Molecular methods are also important tools for diagnosis in animals that do not show serological responses [35]. As previously reported for other domestic species [21][22][23], our results show that PCR and sequencing are important tools for the detection and characterization of leptospires in semen at swine artificial insemination centers.…”

“…santarosai serovars or any characterized local isolates. Molecular methods are also important tools for diagnosis in animals that do not show serological responses [ 35 ]. As previously reported for other domestic species [ 21 – 23 ], our results show that PCR and sequencing are important tools for the detection and characterization of leptospires in semen at swine artificial insemination centers.…”

The role of small ruminants in the epidemiology of leptospirosis

“…A variety of primers, some of which are only specific for the genus Leptospira and others designated to identify only pathogenic species, are used, These PCR assays do not identify the infecting serovar, although it is possible to identify a specific species by sequencing the PCR amplicons 31 . According to the literature, the PCR method targeting the 16S ribosomal RNA subunit are the useful diagnostic molecular technique for the direct diagnosis of leptospirosis and is able to detect approximately 10 genome equivalents /mL of whole blood, while the PCR method targeting the LipL32 surface protein gene region is able to detect 100 leptospira/mL of whole blood 32 .…”

Leptospira noguchii associated to reproductive disease in ruminants

“…Posteriorly, lip L32 positive samples were subjected to a nested PCR targeting a partial region of the sec Y gene (410 bp), according to Di Azevedo et al. (2020). As reaction negative and positive control, ultrapure water and DNA from L. interrogans serovar Copenhageni (Fiocruz L1‐130) were used, respectively.…”