Lactoperoxidase-catalysed radio-iodination was used to compare the
surface proteins on red cells from Plasmodium yoelii-infected with normal BALB/c mice. The profile of radio-iodinated
proteins separated by SDS-
polyacrylamide gel electrophoresis was different for infected blood of similar parasitaemia from mice inoculated with different doses of the parasite. Inoculation with different doses of the parasite. Inoculation with the lower dose resulted in the appearance of a major radio-iodinated
protein of apparent molecular weight (Mr) 76 000 which was labelled to a similar extent on uninfected red cells from infected blood and purified multinucleate infected cells. Several minor radio-iodinated bands, with identical mobilities to the minor bands on normal BALB/c erythrocytes, were also present on red cells from this infected blood. In contrast, the higher inoculation dose produced changes in the minor labelled bands, and the band with Mr of 76 000 was absent. In this case, the minor radio-iodinated
proteins of the normal BALB/c erythrocyte (with Mr of 65 000, 57 000, 48 000, 38 000 and 32 000) were replaced by a series of bands with Mr of 60 000, 50 000, 43 000 and 28 000 on both uninfected and infected red cells. These differences with inoculation dose may be related to the different duration of these
infections, the development of anaemia and the extent of pathological changes at the erythrocyte surface. P. yoelii
infection caused a marked loss in
periodate-dependent labelling of
sialoglycoproteins on most, if not all, red cells in infected blood. There was also a large decrease in
galactose oxidase-dependent
glycoprotein labelling with or without
neuraminidase treatment. These changes in the
carbohydrate groups on red cell membrane
glycoproteins may be linked to the excessive loss of both uninfected and infected red cells during some
malaria infections.