Table 1.

Genetically altered live-attenuated vaccine candidates against visceral leishmaniasis.

Parasite	Characterization of attenuation	Animal model	Results of Immunization	References
L. donovani	Biopterin transporter gene deleted parasite (BT1−/−)	BALB/c mice	Protective immunity, antigen-specific IFNγ secretion	[87]
L. tarentolae	Nonpathogenic strain expressing L. donovani A2 antigen	BALB/c mice	Protective immunity against L. infantum challenge, high IFNγ, low IL-5	[98]
L. donovani	Replication deficient centrin gene deleted (Cen−/−)	BALB/c mice, Syrian hamster	Protective immunity against L. donovani and L. braziliensis challenge. Increased IFNγ, IL-2, and TNF producing cells and IFNγ/IL-10 ratio	[53]
L. infantum	Silent information regulatory 2 single allele deletion (SIR2+/−)	BALB/c mice	Protective immunity, increased antigen-specific IFNγ/IL-10 ratio	[89]
L. donovani	Cytochrome c oxidase complex component p27 gene deleted cell line (Ldp27−/−)	BALB/c mice	12-week survival in host, initial evidence of protective immunity	[97] and Dey, unpublished