Anti-Leishmania infantum IgG Antibody Avidity in Visceral Leishmaniasis

Abstract

bIgG avidity tests are used to discriminate acute from chronic infections. There are few reports on the IgG avidity profile of patients with visceral leishmaniasis (VL). This study investigated the anti-Leishmania IgG avidity in patients with classic VL (n ‫؍‬ 10), patients showing clinical cure after treatment (n ‫؍‬ 18), and asymptomatic subjects with at least one positive Leishmania test (n ‫؍‬ 20). All subjects were from areas in Brazil where VL is endemic. Serum samples were collected from each subject on two different occasions. IgG avidity was evaluated by Western blotting. The proportion of high-avidity antibodies was higher in all samples from patients with classic VL. In contrast, low-avidity antibodies predominated in subjects with a history of VL, including 13 cases (72.2%) in the first assessment and 14 (77.8%) in the second. Fifteen (75%) of the asymptomatic subjects presented a predominance of low-avidity antibodies in the first assessment, and the frequency of high-avidity antibodies increased over time in seven subjects (35%) of this group. Antibodies against the 14-and/or 16-kDa antigen fraction were detected in the first assessment in all patients with classic VL, in 10 (55.5%) treated patients, and in 10 (50%) asymptomatic subjects. These were highavidity antibodies in most cases. In the asymptomatic group, an increase in IgG avidity against the 14-and/or 16-kDa antigen fraction was observed in three cases (15%). The results indicate distinct responses in infected and asymptomatic subjects, probably associated with the length of time after infection. In this respect, IgG avidity tests represent a new approach to better characterize asymptomatic VL.

Socio‐epidemiological characterisation of blood donors with asymptomatic Leishmania infantum infection from three Brazilian endemic regions and analysis of the transfusional transmission risk of visceral leishmaniasis

“…The ELISA test was performed, following the manufacturers' instructions, for all cellular blood component recipients who agreed to participate in the study. Western blots were processed as described in Tiburcio (), with 14 or 18 kDa bands considered positive. The conventional PCR was performed according to the following protocols:…”

Prospection of immunological biomarkers for characterization and monitoring of asymptomatic Leishmania (Leishmania) infantum infection

“…High avidity IgG antibodies were predominant in individuals with VL, with only 10% of samples presenting low avidity IgG antibodies. These data are consistent with the long incubation period generally observed in the disease (Tiburcio et al ., 2013).…”

Evaluation of a novel lentiviral vaccine expressing KMP11‐HASPB fusion protein against Leishmania infantum in BALB/c mice

“…There are conflicting ideas about the role of antibodies in immunity against the parasite. Some studies showed that antibodies increased the immunity against Leishmania mexicana and L. infantum . On the contrary, Rodrigues et al.…”