Investigation of chronic infection by Leptospira spp. in asymptomatic sheep slaughtered in slaughterhouse

PLoS One. 2019 May 23;14(5):e0217391. doi: 10.1371/journal.pone.0217391. eCollection 2019.

Abstract

The study aimed to evaluate the histopathological characteristics of renal lesions in chronically infected sheep and with low titers of anti-Leptospira antibodies from a slaughterhouse. In the serological analysis, 24.74% (48/194) presented seroreactivity with a titer equal to or greater than 100. Among these seroreactive sheep, titers of 100 were predominant (58.33%, 28/48), with the highest titer being 1,600 (2.08%, 1/48). Serogroup Sejroe (sv. Hardjo) was the most frequent at 35.42% (17/48). Leptospiral DNA was verified in 4.12% (8/194) of the kidney samples tested, and no urine sample was positive. All the samples corresponded to the pathogenic species L. interrogans. The eight amplicons with 202-nucleotides were identical with two mismatches (presented 100% of identity) using the PCR targeting to secY gene. Histological sections of PCR-positive kidneys were submitted to direct detection by the anti-LipL32 immunohistochemistry (IHC) technique. The Leptospira spp. antigen was evident in 62.5% (5/8) of the kidneys. Positive staining was observed in the cytoplasm of tubular cells and in the form of brownish aggregates that adhered to tubular epithelial cells and projected into the lumen. Inflammatory lymphoplasmacytic infiltrate, ranging from mild to moderate, with multifocal distribution, was the predominant finding in seroreactive animals (33.33%, 16/48). The demonstration of the leptospiral antigen lining the renal tubules through IHC of naturally infected sheep confirmed by PCR characterizes renal colonization in a species with the presence of histological changes compatible with leptospirosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abattoirs
  • Animals
  • Antibodies, Bacterial / blood
  • Antigens, Bacterial / genetics
  • Asymptomatic Infections
  • Brazil
  • Chronic Disease
  • DNA, Bacterial / genetics
  • Disease Reservoirs / microbiology
  • Disease Reservoirs / veterinary
  • Kidney / microbiology
  • Kidney / pathology
  • Leptospira interrogans* / genetics
  • Leptospira interrogans* / immunology
  • Leptospira interrogans* / pathogenicity
  • Leptospirosis / microbiology
  • Leptospirosis / pathology
  • Leptospirosis / veterinary*
  • Serogroup
  • Sheep
  • Sheep Diseases / microbiology*
  • Sheep Diseases / pathology
  • Sheep, Domestic / microbiology*

Substances

  • Antibodies, Bacterial
  • Antigens, Bacterial
  • DNA, Bacterial

Grants and funding

This study was funded by the Foundation for Research Support of the State of Bahia, Brazil (http://www.fapesb.ba.gov.br/), Public Notice no. 025/2010 under Term of Grant PPP 0034/2011, coordinated by Melissa Hanzen Pinna. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.