Kinetics of Leishmania Antibodies after Challenge Measured by Indirect ELISA
*Joan Ferrer, Xavier Rebordosa, Carlos Artigas, JuanJosé Zarate, Iñaki Arbea, Mª Jesús Ramiro
*Laboratorios Hipra, S.A.
Amer, Girona, ES
Canine Leishmaniasis is a disease caused by a protozoan of the genus Leishmania. The objective of this study is to check the evolution of antibodies against Leishmania after a challenge in Beagle dogs and the suitability of indirect ELISA for the detection of infection. The level of antibodies was compared with the onset of general clinical signs and was followed during 16 months after challenge.
For this trial 10 female Beagle dogs were used. All animals were adult and younger than 2 years. All animals had been currently vaccinated and before starting the trial a general health checkout was performed. Before starting the trial all animals were dewormed. Animals were distributed randomly in two groups and after 3 months one group was infected with Leishmania infantum. The other group was kept as a negative control. For the measurement of ELISA antibodies a commercial test, Civtest Canis Leishmania (HIPRA), was used. The test uses Leishmania coated microtiter wells and results are given in relation to a positive control serum. Ratios higher than 1.0 are considered positive.
Among the animals in the infected group, two seroconverted after 8 months, one after 10 months, one after 11 months, and the last one after 12 months, reaching the highest level of antibodies in one or two months. None of the animals of the negative control group seroconverted. Once the animals have seroconverted, titres remained high throughout the rest of the trial. Clinical signs appeared in all infected animals. First general clinical signs appeared in three cases 1 month after seroconversion, in one case 3 months later and in the last one the appeared almost simultaneously. None of the animals of the negative group had clinical signs.
The indirect ELISA test (Civtest Canis Leishmania) has demonstrated to be suitable for the detection of disease as has identified clearly the onset of antibodies against Leishmania. In all infected animals antibodies against Leishmania appeared 8 - 12 months after challenge. This period of time is longer than the one expected for natural infection. On the other side, the ELISA test has demonstrated to have excellent specificity as no false positive results have appeared throughout the study. Although in the light of the results obtained here, serology has identified correctly infected and non-infected animals, performing other tests will be necessary in clinical practice to confirm or not the presence of Leishmaniosis.