# Detection of Serum IgG Specific for Brachyspira pilosicoli and “Brachyspira canis” in Dogs

## TL;DR

This study developed tests to detect antibodies in dogs against two Brachyspira species, which may help understand their role in canine health.

## Contribution

The study introduces new ELISAs using TCA-precipitated antigens to detect specific IgG antibodies against Brachyspira pilosicoli and Brachyspira canis in dogs.

## Key findings

- Detergent-extracted antigens from Brachyspira species showed shared epitopes recognized by canine IgG antibodies.
- Many dogs tested had IgG antibodies specific to both Brachyspira pilosicoli and Brachyspira canis.
- TCA precipitation improved the specificity of antigen preparations for antibody detection.

## Abstract

This study established laboratory tests for the detection of specific antibodies against bacteria of the genus Brachyspira in the sera of dogs. By causing inflammation of the large intestine, distinct species of Brachyspira can cause disease in several different animal species, such as pigs and poultry, as well as humans. In dogs, Brachyspira pilosicoli and “Brachyspira canis” have been isolated from fecal samples and rectal swabs. The former can cause clinical signs, such as diarrhea and reduced growth, in pigs and poultry, as well as reduced egg production in poultry. The latter species is generally considered apathogenic. This study evaluates different antigen preparations of these bacteria for their suitability to detect specific antibodies. We were able to select a suitable antigen preparation and detect specific antibodies against both Brachyspira species in individual dogs. These laboratory tests are expected to help indirectly detect infection in dogs in the future and to better understand the role of Brachyspira as a putative pathogen in dogs.

Brachyspira pilosicoli (B. pilosicoli) is a pathogen in pigs, poultry, and humans causing colitis, diarrhea, and poor growth rates. Its role as a canine pathogen is controversial, and the seroprevalence of specific IgG antibodies against B. pilosicoli in dogs is unknown. A further, not yet officially recognized Brachyspira species in dogs is “Brachyspira canis” (“B. canis“), which is proposed to be apathogenic. This study evaluates enzyme-linked immunosorbent assays (ELISAs) measuring serum IgG antibodies specific for B. pilosicoli or “B. canis” and investigates levels of specific IgG antibodies against B. pilosicoli and “B. canis” in a cohort of clinical patients presented at an animal referral clinic. These ELISAs use detergent-extracted antigens from B. pilosicoli and “B. canis”. To increase analytic specificity, we precipitated the antigens with trichloroacetic acid (TCA) to isolate and concentrate the respective protein fraction. Our results indicate that a large number of serum IgG antibodies bind to shared epitopes of detergent-extracted antigens of the two spirochaetes. Our data also suggest that dogs might not only carry B. pilosicoli but also have “B. canis”-specific serum IgG antibodies.