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TRANSMISSION BLOCKING VACCINE STUDIES IN LEISHMANIASIS: 11. EFFECT OF IMMUNISATION USING LEISHMANIA MAJOR DERIVED 63 KILODALTON GLYCOPROTEIN, LIPOPHOSPHOGLYCAN AND WHOLE PARASITE ANTIGENS ON THE COURSE OF L. MAJOR INFECTION IN BALBIC MICE
Abstract
Background: Safe, effective and inexpensive vaccines may be the most practical tool for control
of any form of leishmaniasis. Leishmaniasis produces a state of pre-immunition which is the
underlying mechanism for prolonged immunity to re-infection. Low doses of parasites has been
shown to beable to induce protection in mice. It is not known, however, how immunesel-a from
a susceptible host imrnunised with Leishmania-derived antigens when taken in by the sandfly
affects the development and the subsequent transmission of the parasite to naive hosts.
Objective: To monitor the course of disease in BALBlc mice following challenge using L.
rnajor infected P. duboscqi which had previously fed on immunised mice.
Methods: BALBIc mice were immunised adequately withLeishrnania major-derived antigens
namely, crude whole parasite (WPA), recombinant 63 kilodalton glycoprotein (rgp63),
lipophosphoglycan (LPG;) ancl a cocktail composed of rgp63 plus LPG antigens. Laboratory
reared Phlebotornus duboscqi sandflies, the natural vector for L. major were later allwwed to
feed on immunised animals, interrupted and allowed to continue feeding on infected animals
for an equal amount of time until they became fully engorged. The sandflies were maintained
on apples as a carbohydrate source in an insectary maintained at a temperature of 2S°C and
80% relative humidity. On the seventh day these sandflies were used to infect naivc B:ALB/
c mice and the course of infection followed for a period of at least three months.
Results: Mice infected usingsandflies which had previously fed on WPA or rgp63-immunized
mice showed disease exacerbation as the infection progressed, whereas those infected using
sandflies which had previously fed on LPG-immunised mice had the least lesion sizes
compared to control mice infected using sandflies which had fed on saline immunised mice
(p<0.05).
Conclusions: Results from this study indicate that the course of L. major infection in BALBI
c mice was dependent on the infective dose of parasites transmitted by the sandflies. R~:sults
from this study suggests that sub-infective doses of the parasite from sandflies previously fed
on animals immunised with Leishmania-derived antigens needs to be evaluated for their
potential in vaccine development against Leishmania infections.
of any form of leishmaniasis. Leishmaniasis produces a state of pre-immunition which is the
underlying mechanism for prolonged immunity to re-infection. Low doses of parasites has been
shown to beable to induce protection in mice. It is not known, however, how immunesel-a from
a susceptible host imrnunised with Leishmania-derived antigens when taken in by the sandfly
affects the development and the subsequent transmission of the parasite to naive hosts.
Objective: To monitor the course of disease in BALBlc mice following challenge using L.
rnajor infected P. duboscqi which had previously fed on immunised mice.
Methods: BALBIc mice were immunised adequately withLeishrnania major-derived antigens
namely, crude whole parasite (WPA), recombinant 63 kilodalton glycoprotein (rgp63),
lipophosphoglycan (LPG;) ancl a cocktail composed of rgp63 plus LPG antigens. Laboratory
reared Phlebotornus duboscqi sandflies, the natural vector for L. major were later allwwed to
feed on immunised animals, interrupted and allowed to continue feeding on infected animals
for an equal amount of time until they became fully engorged. The sandflies were maintained
on apples as a carbohydrate source in an insectary maintained at a temperature of 2S°C and
80% relative humidity. On the seventh day these sandflies were used to infect naivc B:ALB/
c mice and the course of infection followed for a period of at least three months.
Results: Mice infected usingsandflies which had previously fed on WPA or rgp63-immunized
mice showed disease exacerbation as the infection progressed, whereas those infected using
sandflies which had previously fed on LPG-immunised mice had the least lesion sizes
compared to control mice infected using sandflies which had fed on saline immunised mice
(p<0.05).
Conclusions: Results from this study indicate that the course of L. major infection in BALBI
c mice was dependent on the infective dose of parasites transmitted by the sandflies. R~:sults
from this study suggests that sub-infective doses of the parasite from sandflies previously fed
on animals immunised with Leishmania-derived antigens needs to be evaluated for their
potential in vaccine development against Leishmania infections.
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