Jr. Mineo et al., TOXOPLASMA-GONDII - A MONOCLONAL-ANTIBODY THAT INHIBITS INTRACELLULARREPLICATION, Experimental parasitology, 79(3), 1994, pp. 351-361
During its intracellular life cycle within the infected host cell, Tox
oplasma gondii is able to undergo rapid asexual replication. Neither t
he mechanism by which the parasite initiates this process nor the requ
irements for maintaining it are understood. We produced a monoclonal a
ntibody, 1B8, that identifies a parasite antigen of approximate M(r) 9
7 kDa as determined by SDS-PAGE. The epitope recognized by mAb 1B8 app
ears as a collection of vesicular structures scattered throughout the
cell cytoplasm. When RH strain parasites are incubated with mAb 1B8 in
the absence of serum complement, parasite growth is inhibited by >90%
as determined by radioisotope incorporation. Both attachment and inva
sion assays show that neither of these parasite-host cell interactions
are inhibited by the mAb. However, a marked reduction in the number o
f intracellular rosettes was observed following mAb treatment of the p
arasites. Viable extracellular parasites are able to endocytose mAb 1B
8. Once within the parasite cytosol the antibody recognizes the vesicu
lar structures similar to those observed with fixed parasites. Immunof
luorescence assays with Besnoitia jellisoni and Plasmodium falciparum
show that the epitope recognized by mAb 1B8 is conserved among Coccidi
ae but not the kinetoplastid Leishmania. (C) 1994 Academic Press, Inc.