Novel recombinant multiepitope proteins for the diagnosis of asymptomatic leishmania infantum-infected dogs.

Visceral leishmaniasis is the most severe form of leishmaniasis. Worldwide, approximately 20% of zoonotic human visceral leishmaniasis is caused by Leishmania infantum, also known as Leishmania chagasi in Latin America. Current diagnostic methods are not accurate enough to identify Leishmania-infected animals and may compromise the effectiveness of disease control. Therefore, we aimed to produce and test two recombinant multiepitope proteins as a means to improve and increase accuracy in the diagnosis of canine visceral leishmaniasis (CVL). Ten antigenic peptides were identified by CVL ELISA in previous work. In the current proposal, the coding sequences of these ten peptides were assembled into a synthetic gene. Furthermore, other twenty peptides were selected from work by our group where good B and T cell epitopes were mapped. The coding sequences of these peptides were also assembled into a synthetic gene. Both genes have been cloned and expressed in Escherichia coli, producing two multiepitope recombinant proteins, PQ10 and PQ20. These antigens have been used in CVL ELISA and were able to identify asymptomatic dogs (80%) more effectively than EIE-LVC kit, produced by Bio-Manguinhos (0%) and DPP kit (10%). Moreover, our recombinant proteins presented an early detection (before PCR) of infected dogs, with positivities ranging from 23% to 65%, depending on the phase of infection in which sera were acquired. Our study shows that ELISA using the multiepitope proteins PQ10 and PQ20 has great potential in early CVL diagnosis. The use of these proteins in other methodologies, such as immunochromatographic tests, could be beneficial mainly for the detection of asymptomatic dogs.