Host responses to Borrelia burgdorferi in dogs and horses.

The research explores how dogs and horses respond to the bacteria Borrelia burgdorferi, which causes Lyme disease. This includes monitoring the production of antibodies (IgM and IgG) in clinically infected and asymptomatic animals, with the finding that disease expression could occur if untreated, even in cases without symptoms.

Analysis of Host Responses in Dogs

• The researchers tested the immune responses (specifically IgM and IgG) in dogs infected with Borrelia burgdorferi using Enzyme-Linked Immunosorbent Assay (ELISA) and Western blot techniques.
• It was found that the antibodies in clinically seropositive dogs (dogs that test positive for the disease) bound to a range of antigenic determinants (parts of foreign bodies that trigger the immune response).
• Evidence showed that the initial response of the immune system (the IgM response) to the flagellin (a protein present in the bacteria causing Lyme disease) persisted for at least 9 months and involved up to seven other peptides (small proteins).
• The IgG response, which usually develops later in Lyme disease, incorporated more immunogens (foreign substances that trigger the immune response) than are currently acknowledged in advanced human Lyme disease.
• Interestingly, some dogs that had no symptoms of Lyme disease were found to be seropositive, indicating they had been infected with the bacteria and had produced antibodies. These asymptomatic dogs later developed clinical signs of the disease.
• The persistence of B. burgdorferi in both asymptomatic and weakly reactive animals was highlighted in immunoblot studies. The research suggests that if this condition is untreated, it could lead to disease manifestation.

Analysis of Host Responses in Horses

• Similarly to the study in dogs, the immune responses of clinically seropositive horses, asymptomatic seronegative horses (those without symptoms and testing negative for Lyme disease), and experimentally infected horses were also analyzed.
• In these horses, IgG antibodies initially responded to the flagellin and later to polypeptides of 34 and 31-kDa, even when ELISA test results were considered only slightly reactive indicating a low level of antibodies present. This suggests that horses, like dogs, may carry the bacteria and produce antibodies without showing symptoms of Lyme disease.

This research offers valuable insights into the immune responses of dogs and horses to the bacteria B. burgdorferi and opens up avenues for more extensive research into the treatment of Lyme disease in these and other animals.