Evaluation of canine anti-Leishmania IgG subclasses and their relation with skin signs in naturally infected dogs in the northwest of Iran

Canine leishmaniasis (CanL) is a severe, intracellular parasitic zoonosis and is an endemic complaint in Iran. Dogs are considered the reservoir host for Leishmania infantum in the Old World. The aims of this study were to evaluate the relation between anti-Leishmania antibody titers (IgG) and skin symptoms of CanL in naturally affected dogs and to assess the correlation of IgG(1) and IgG(2) subclasses of titers with these symptoms. Anti-Leishmania antibody titers were evaluated in 100 dogs' blood samples with the direct agglutination test (DAT) and enzyme-linked immunosorbent assay (ELISA) methods. Based on DAT results, 45 samples were positive. Twenty-five of the positive dogs had cutaneous signs of leishmaniasis and 20 of them were asymptomatic (DAT of 1: 320 and above). In the dogs, high levels of total IgG were found in symptomatic dogs. In ELISA, we found an apparent correlation between IgG(1) and symptomatic dogs and between IgG(2) and asymptomatic dogs. It seems that measurements of IgG subclasses can be used as gold-standard markers for evaluation of susceptibility or resistance to this lethal chronic infectious disease in dogs.