ANTI-LEISHMANIA IgG ANTIBODY AVIDITY IN VISCERAL LEISHMANIASIS

18 IgG avidity tests are used to discriminate acute from chronic infections. There are few 19 reports on the IgG avidity profile of patients with visceral leishmaniasis (VL). This study 20 investigated the anti-Leishmania IgG avidity in patients with classic VL (n=10), patients 21 showing clinical cure after treatment (n=18), and asymptomatic subjects with at least one 22 positive Leishmania test (n=20). All subjects were from endemic areas in Brazil. Serum 23 samples were collected from each subject on two different occasions. IgG avidity was 24 evaluated by Western blotting. The proportion of high-avidity antibodies was higher in all 25 samples from patients with classic VL. In contrast, low-avidity antibodies predominated in 26 subjects with a history of VL, including 13 cases (72.2%) in the first assessment and 14 27 (77.8%) in the second. Fifteen (75%) of the asymptomatic subjects presented a 28 predominance of low-avidity antibodies in the first assessment and the frequency of high29 avidity antibodies increased over time in seven subjects (35%) of this group. Antibodies 30 against the 14and/or 16-kDa antigen fractions were detected in the first assessment in all 31 patients with classic VL, in 10 (55.5%) treated patients, and in 10 (50%) asymptomatic 32 subjects. These were high-avidity antibodies in most cases. In the asymptomatic group, an 33 increase in IgG avidity against the 14and/or 16-kDa antigen fractions was observed in 34 three cases (15%). The results indicate distinct responses in infected and asymptomatic 35 subjects, probably associated with the length of time after infection. In this respect, IgG 36 avidity tests represent a new approach to better characterize asymptomatic VL. 37 38 on S etem er 0, 2017 by gest httpcvi.asm .rg/ D ow nladed fom