# Protective Effects of rLPG3 Plus Freund’s Incomplete Adjuvant on Parasitism, Hepatic Function, and Immune Modulation in Experimental Visceral Leishmaniasis

## TL;DR

This study shows that a vaccine made from rLPG3 and FIA can protect mice from visceral leishmaniasis by reducing parasites in the liver and improving immune and liver health.

## Contribution

The study introduces rLPG3 as a promising antigen for visceral leishmaniasis vaccines, showing protective effects in a mouse model.

## Key findings

- rLPG3+FIA reduced liver parasites and improved antioxidant enzyme activity in mice.
- The vaccine preserved liver structure and reduced granuloma formation and liver enzyme levels.
- It induced a Th2 immune response, as shown by increased IgG1 and IgG1/IgG2a ratio.

## Abstract

Visceral leishmaniasis (VL) is a neglected tropical disease
affecting
humans and dogs, particularly in urban settings. Current therapies
are limited by toxicity, lengthy regimens, and emerging drug resistance.
No human vaccine is available, and only a few licensed formulations
exist for canine use. Here, we evaluated a recombinant Leishmania
infantum lipophosphoglycan-3 (rLPG3) antigen formulated with Freund’s
incomplete adjuvant (FIA) against Leishmania infantum challenge in BALB/c mice. The formulation reduced hepatic parasitism,
increased antioxidant enzyme activities (superoxide dismutase, catalase,
glutathione S-transferase), and raised total antioxidant capacity
and hepatic nitrite/nitrate, while lipid and protein oxidation markers
remained unchanged. Vaccination preserved liver architecture, lowered
AST/ALT, reduced granuloma number and area, and shifted granuloma
maturation toward organized lesions with greater macrophage content;
PAS staining indicated higher hepatocyte glycogen in the rLPG3+FIA
group. Serologically, rLPG3+FIA increased IgG1 and the IgG1/IgG2a
ratio, indicating a Th2-skewed profile concomitant with reduced parasitism.
Within the constraints of this model, time point, and the proof-of-concept
use of FIA, these convergent readouts support rLPG3 as a promising
antigen for further preclinical developmentprioritizing licensable
veterinary adjuvants to enable translation into canine VL vaccines.