A heterologous prime-boost vaccination regimen using ORFF DNA and recombinant ORFF protein confers protective immunity against experimental visceral leishmaniasis.
OBJECTIVE
We describe the effectiveness of a prime-boost vaccination regimen using the open-reading frame (ORFF) gene from the LD1 locus of Leishmania donovani.


METHODS
A group of BALB/c mice was immunized with the plasmid carrying the gene for ORFF (F/pcDNA 3.1) and given a booster dose of either the same DNA vaccine or a vaccine with a recombinant ORFF (rORFF) protein. Another group of BALB/c mice was immunized and given a booster dose of the rORFF protein vaccine. The protective efficacies of these vaccine formulations were compared after challenge with L. donovani stationary-phase promastigotes.


RESULTS
Mice given the prime-boost vaccination regimen had an enhanced reduction in parasite load (75%-80%), compared with that in mice given only the rORFF protein vaccine (45%-60%). However, the protective response induced in the prime-boost group was not more than that elicited in the DNA vaccine group. Immunization with only the rORFF protein vaccine did not induce the typical T helper response, whereas priming with the DNA vaccine resulted in enhanced production of immunoglobulin G2a and interferon- gamma . Furthermore, priming with the DNA vaccine also led to enhanced proliferation of splenocytes, suggesting subsequent expansion of antigen-specific T cells.


CONCLUSIONS
The heterologous prime-boost vaccination strategy may be utilized for visceral leishmaniasis.
Tewary
Poonam
P
School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
Jain
Manju
M
Sahani
Mayurbhai H
MH
Saxena
Shailendra
S
Madhubala
Rentala
R
D000818:Animals; D005260:Female; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007371:Interferon-gamma / Q000097:blood; D018664:Interleukin-12 / Q000097:blood; D015847:Interleukin-4 / Q000097:blood; D007893:Leishmania donovani / Q000276:immunology; D007898:Leishmaniasis, Visceral / Q000517:prevention & control*; D051379:Mice; D008807:Mice, Inbred BALB C; D015800:Protozoan Proteins / Q000276:immunology*; D016052:Protozoan Vaccines / Q000008:administration & dosage*; D019444:Vaccines, DNA / Q000008:administration & dosage*; D014614:Vaccines, Synthetic / Q000008:administration & dosage
C402106:ORFF protein, Leishmania; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; D019444:Vaccines, DNA; D014614:Vaccines, Synthetic; D018664:Interleukin-12; D015847:Interleukin-4; D007371:Interferon-gamma