Pathogenic Leptospira and their animal reservoirs: testing host specificity through experimental infection

Abstract

Leptospirosis is caused by pathogenic Leptospira transmitted through contact with contaminated environments. Most mammalian species are infectable by Leptospira but only few act as efficient reservoir being capable of establishing long term kidney colonization and shedding Leptospira in urine. In Madagascar, a large diversity of pathogenic Leptospira display a tight specificity towards their endemic volant or terrestrial mammalian hosts. The basis of this specificity is unknown: it may indicate some genetically determined compatibility between host cells and bacteria or only reflect ecological constraints preventing contacts between specific hosts. In this study, Rattus norvegicus was experimentally infected with either Leptospira interrogans, Leptospira borgpetersenii or Leptospira mayottensis isolated from rats, bats or tenrecs, respectively. Leptospira borgpetersenii and L. mayottensis do not support renal colonization as featured by no shedding of live bacteria in urine and low level and sporadic detection of Leptospira DNA in kidneys. In contrast 2 out of the 7 R. norvegicus challenged with L. interrogans developed renal colonization and intense Leptospira shedding in urine throughout the 3 months of experimental infection. These data suggest that host-Leptospira specificity in this biodiversity hotspot is driven at least in part by genetic determinants likely resulting from long-term co-diversification processes.

Amplification of pathogenicLeptospirainfection with greater abundance and co‐occurrence of rodent hosts across a counter‐urbanizing landscape

“…Consistent with this, Theuerkauf et al (2013) found that Leptospira infection in several rodent hosts increased following the introduction of non-native black rats (Rattus rattus) to a Polynesian island, suggesting that a rise in rodent diversity amplified host infection. Evidence of host specificity and multiple Leptospira species within individuals suggests that this might be a result of cross-infection among co-occurring host species (Cordonin et al, 2019(Cordonin et al, , 2020Moseley et al, 2018). Other work suggests, however, that host diversity reduces infection prevalence.…”

Urban rat exposure to anticoagulant rodenticides and zoonotic infection risk

“…1 week). Experimental work has demonstrated successful Leptospira infection 7 days post-infection [32,33], yet further work is needed to examine Leptospira spp. infection dynamics at a shorter timescale and determine how long rats can survive following AR exposure.…”

Tracking animal reservoirs of pathogenic Leptospira: the right test for the right claim

“…This absence of colonization might be related to a low infecting dose and/or from an infecting bacterial genomospecies that is unable to establish persistent renal colonization in a specific vertebrate species. This assumption is based on the existence of host- Leptospira molecular determinants required for renal colonization, an hypothesis substantiated by experimental infections in which bat-borne and Tenrec-borne Leptospira were not able to lead to chronic infection in rats (Cordonin et al . 2020).…”