3 research outputs found
Virulence Attenuation of a UDP-galactose/ N-acetylglucosamine β1,4 Galactosyltransferase Expressing Leishmania donovani Promastigote
Protozoan parasites of the genus Leishmania are
the causative agent of leishmaniasis, a disease whose
manifestations in humans range from mild cutaneous
lesions to fatal visceral infections. Human visceral leishmaniasis
is caused by Leishmania donovani. Long-term
culture in vitro leads to the attenuation of the parasite. This
loss of parasite virulence is associated with the expression
of a developmentally regulated UDP-Galactose/N-acetylglucosamine
β 1–4 galactosyltransferase and galactose
terminal glycoconjugates as determined by their agglutination
with the pea nut agglutinin (PNA). Thus, all promastigotes
passaged for more than 11 times were 100%
agglutinated with PNA, and represent a homogeneous
population of avirulent parasites. Identical concentrations
of PNA failed to agglutinate promastigotes passaged for ≤5
times. These PNA− promastigotes were virulent. Promastigotes
passaged from 5 to 10 times showed a mixed
population. The identity of populations defined by virulence
and PNA agglutination was confirmed by isolating
PNA+ avirulent and PNA− virulent clones from the 7th
passage promastigotes. Only the PNA+ clones triggered
macrophage microbicidal activity. The PNA+ clones lacked lipophosphoglycan. Intravenous administration of [14C]
galactose-labeled parasite in BALB/c mice resulted in rapid
clearance of the parasite from blood with a concomitant
accumulation in the liver. By enzymatic assay and RT-PCR
we have shown the association of a UDP-Galactose/Nacetylglucosamine
β1,4 galactosyltransferase with only the
attenuated clones. By immunofluorescence we demonstrated
that the enzyme is located in the Golgi apparatus. By
western blot analysis and SDS-PAGE of the affinitypurified
protein, we have been able to identify a 29 KDa
galactose terminal protein from the avirulent clones