Implications of antibodies to pyruvylated glucose in healthy populations for mycobacterioses and other infectious diseases

Abstract

Members of the Mycobacterium avium-Mycobacterium intracellulare (MAI) complex are typeable because each serovar is characterized by its own specific antigenic glycolipid. By means of an enzyme-linked immunosorbent assay, we studied serum specimens obtained from 148 healthy college students for antibodies to these glycopeptidolipids. Ninety-two (61.5%) of the serum specimens were positive to the specific glycolipid antigen from MAI serovar 8. In a study of a pediatric population, antibodies appeared to develop during adolescence. Individuals with overt mycobacterial disease had a significantly lower incidence (tuberculosis patients, 34.5%; leprosy patients, 25%). We found a lower incidence of positive results in a survey of 96 Japanese serum specimens (29.1%), but the results from a survey of sera obtained from Bombay, India, indicated a large degree of reactivity (55.5%). Antibodies to other MAI serovars (serovars 2, 4, and 11) were not found, except antibodies to MAI serovar 21 were seen in the same individuals with antibodies to serovar 8. The dominant epitope of the MAI serovar 8-specific glycopeptidolipid is a terminal pyruvylated 3-O-methylglucose residue [4,6-(1'-carboxyethylidene)-3-O-methyl-alpha-D-glucopyranosyl] unit, whereas that of the MAI serovar 21 has the same terminal pyruvylated glucose devoid of the 3-methoxy group. Thus the antibodies appear specific for the pyruvylated glucose. It is unclear whether the high prevalence of antibodies to these epitopes reflects a high incidence of subclinical colonization or infection with certain MAI serovars or whether they are acquired through contact with some other related antigen source.