Lindberg A A, LeMinor L


Lindberg A A, LeMinor L. -1,6. It also results in a loss of an O-acetyl group from the Gal residue (Fig. ?(Fig.1).1). This change is believed to be responsible for the loss of O-10, and in its place, these organisms express a new O antigen, O-15. Some of these organisms may additionally harbor another phage, ?34, and this imparts to these organisms an additional O antigen 34 specificity which is related to the glycosylation of the Gal residue on Nog the ?15-lysogenized variants’ lipopolysaccharide (LPS) backbone (8). Open in a separate window FIG. 1 Structure of an O-antigenic polysaccharide unit of subsp. serogroup E LPS. Gal, galactose; Man, mannose; Rha, rhamnose. Footnotes: a, X = O-acetyl6 (nonlysogenic serogroup E1), X ? (?15-lysogenized serogroup E1), d-glucose 14 (?15- and ?34-lysogenized serogroup E1), or d-glucose 16 (serogroup E4); or anomeric linkage is for nonlysogenic serogroup E1 and serogroup E4, for lysogenic serogroup E1. Serotyping of O antigens to identify the phage-modified variants within serogroup E1 is still of epidemiological significance, especially for public health reasons. This work is complicated by the fact that strains may express the O factors 1, 3, 10, 15, 19, and 34 in different combinations (i.e., 3,10; 3,15; 3,15,34; 1,3,19; 1,3,10,19; and 1,3,15,19) (2, 7). With some single factor O antisera being withdrawn from the market by commercial producers, more-detailed serotyping can be achieved only at reference laboratories at which the tedious task of production and purification of O-factor-specific antisera is still carried out with animals. Monoclonal antibodies (MAbs), with their exquisite specificity, can be an efficient alternative to conventional antisera in serogroup differentiation (10, 13). Their monospecificities allow detailed mapping of epitopes within the LPS structures, and MC-VC-PABC-DNA31 their simple, high-yielding production makes generation of large volumes of these highly specific reagents of consistent quality a simple task. In addition, MAbs can be produced in vitro by using artificial capillary systems (1) and thus will not require the continued use of laboratory animals in antibody production once the hybridoma cell line is established. The use of MAbs in serology, however, has not gained broad popularity. This is in part due to the fact that their reaction patterns are not identical to those of conventional antisera. The intrinsic high MC-VC-PABC-DNA31 specificity of MAbs is the main factor contributing to this discrepancy. Within a colony there may exist subpopulations exhibiting different somatic MC-VC-PABC-DNA31 antigens (2, 5). This phenomenon, called from variation, is usually associated with postpolymerization modifications such as acetylation and glycosylation (2, 4). Once such variation is introduced, the monospecific MAbs may no longer be able to react with the subpopulation that has undergone this change, whereas a conventional antiserum will intrinsically be able to compensate because of its polyclonal nature. (This work was conducted by S. P. Ng in partial fulfillment of the requirements for a Ph.D. from the University of Hong Kong, Hong Kong, People’s Republic of China.) An immunoglobulin G1 MAb, MO15, was produced by the method of Kohler and Milstein (6), using subsp. serovar London var.15+, a phage ?15-lysogenized serogroup E1 strain, as the immunizing strain. The serogroup specificity of MO15 was confirmed by enzyme-linked immunosorbent assay (ELISA) (11) and immunoblotting against polyacrylamide gel electrophoresis-resolved purified LPS (3, 16, 18). The epitope structure of this MAb MC-VC-PABC-DNA31 is best described by O antigen 15, with its specific anomeric linkages of Gal to Man to rhamnose on the backbone of the ?15-lysogenized serogroup E1 LPS (Fig. ?(Fig.1).1). This MAb epitope structure is reflected in the exclusive reaction.