Synthesis and Immunological Evaluation of Virus-Like Particle-Milbemycin A₃/A₄ Conjugates

Milbemycins are macrolide antibiotics with a broad spectrum of nematocidal, insecticidal, and acaricidal activity. To obtain milbemycin A₃/A₄ derivatives suitable for chemical conjugation to protein carriers (milbemycin haptens), succinate linker and a novel 17-atom-long linker containing a terminal carboxylic acid group were attached to the milbemycin core in a protecting group-free synthesis. The obtained milbemycin A₃/A₄ derivatives were coupled to Potato virus Y-like nanoparticles by the activated ester method. The reaction products were characterized and used in mice immunization experiments. It was found that the mice developed weak specific immune responses toward all tested milbemycin haptens.

The structure of the variable regions of mouse monoclonal antibodies to hepatitis B virus core antigen

From a panel of monoclonal antibodies (MoAbs) directed against E. coli-derived native and denatured hepatitis B virus (HBV) core antigen we have selected a set of specific MoAbs which recognize different linear antigenic determinants: MoAb C1-5--cl epitope; MoAb 14K8--less immunogenic N-terminal region; and MoAbs 13C9, 10F10 and 14E11, 14G3--the immunodominant region between amino acids 134 and 140. We have applied the polymerase chain reaction technique to clone Ig VH and VL region genes, and appropriate full-length cDNA clones were obtained and characterized by nucleotide sequence analysis. Among the six heavy chain variable region sequences examined, three VH families were represented. Two of them belong to the 7183 (MoAb C1-5) and 3609 (14B8) families respectively and four, having only two amino acid changes in the CDR2 region, to the J558 family. These four probably are derived from a single expanded B-cell clone. The light chain sequences indicate that their VL are encoded by V kappa 21, V kappa 19 and V kappa 3 germline genes. Unlike VH genes, light chain genes are closely related to known representatives of mouse kappa light chain families and are employed also by MoAbs raised against other antigens.