RESUMO
Naturally exposed dogs of an endemic area were vaccinated with the fucose mannose ligand (FML) antigen of Leishmania donovani in formulation with QuilA saponin. The 100% of vaccinees were seropositive to FML and showed intradermal reaction to L. donovani lysate, 2 months after vaccination. The absorbency values and size of intradermal reaction were both significantly higher in vaccinees than in controls along a 3.5 years period (ANOVA, P<0.0001). The 25% of the control animals (two dogs on the first year and six dogs on the fourth year, respectively) and 5% of the vaccinees (one dog during the fourth year) developed clinical and fatal disease until the end of experiment. This difference was significant (chi(2)=3.93, P<0.05). This means that 95% protection against kala-azar was achieved in vaccinees, after FML-QuilA vaccination (80% of vaccine efficacy (VE)). Leishmania infection was also confirmed, 3.5 years after vaccination, in saline controls that showed positive polymerase chain reaction (PCR) for Leishmania DNA and FML-serology with no intradermal reaction. Higher seropositivities and intradermal reactions with no Leishmanial DNA were detected in vaccinees. The FML-QuilA vaccine induced a significant, long lasting and strong protective effect against canine kala-azar in the field.
Assuntos
Doenças do Cão/prevenção & controle , Leishmaniose Visceral/veterinária , Vacinas Protozoárias/administração & dosagem , Adjuvantes Imunológicos/administração & dosagem , Animais , Anticorpos Antiprotozoários/sangue , Brasil , DNA de Protozoário/genética , DNA de Protozoário/isolamento & purificação , Doenças do Cão/imunologia , Doenças do Cão/parasitologia , Cães , Humanos , Imunidade Celular , Lectinas/administração & dosagem , Lectinas/imunologia , Leishmania donovani/genética , Leishmania donovani/imunologia , Leishmaniose Visceral/imunologia , Leishmaniose Visceral/parasitologia , Leishmaniose Visceral/prevenção & controle , Proteínas de Protozoários/administração & dosagem , Proteínas de Protozoários/imunologia , Saponinas de Quilaia , Saponinas/administração & dosagemRESUMO
Protection against canine kala-azar was investigated in naturally exposed dogs of an endemic area, vaccinated with the fucose mannose ligand (FML)-vaccine of Leishmania donovani. A total of 97% of vaccinees were seropositive to FML and 100% showed intradermal reaction to L. donovani lysate, 7 months after vaccination. The absorbency values and size of intradermal reaction were both significantly higher in vaccinees than in controls (ANOVA, P<0.0001). After 2 years, 92% (chi(2)=6.996; P<0.0025) protection was achieved: only 8% of vaccinees showed mild signs of kala-azar with no deaths while 33% of controls developed clinical or fatal disease. The FML-vaccine induced a significant, long-lasting and strong protective effect against canine kala-azar in the field.
