Artificially Generated Male-Specific Rabbit Antibody Against DBY-Multi-Epitope Fusion Protein And Its Immunoreactive Examination

DEAD (Asp-Glu-Ala-Asp) box polypeptide 3, Y-linked (DBY or Ddx3y) is a candidate gene for male-specific antigen. The DBY gene detected in capacitated mouse sperm codes putative ATP-dependent RNA helicase. The objective was to produce anti-predicted DBY multi-epitope fusion protein antibody, which could be used to determine male specificity of DBY. Epitope prediction is to aid the design of molecules that can mimic structure and function of a genuine epitope, is a useful tool in protein molecule design. This study predicted the DBY epitopes, prepared rabbit poloclonal antibody against DBY multi-epitope fusion protein, then investigated its immunoreactivity. The fusion protein used as the antigen consisted of three regions of DBY with greatest divergence from other family members, cloned together in-frame (with a His tag to facilitate purification). The resulting antibody recognized both the DBY1-2-3 fusion protein and an endogenous DBY protein of the same size. Furthermore, DBY protein was present (Western blot) in testis, male mouse splenocytes and brain, whereas a weaker band was present in the female brain and splenocytes, and finally, ovary produced only a barely visible protein band. Optical density of DBY protein was higher for males versus corresponding tissues from females. Finally, positive signals of DBY1-2-3 antibody were present on only ~60% of mature murine sperm (based on immunofluorescent staining and flow cytometry), in accordance with the expected proportion of Y-bearing sperm. We hypothesized that our antibodies recognized a specific epitope present in subpopulations of mouse sperm. Therefore, we concluded that anti-DBY1-2-3 antibody could be an alternative way of producing antibodies to DBY protein. Furthermore, this novel DBY antibody against a multi-epitope artificial antigen has potential for both investigating male-specific binding of DBY and as a new method of sex selection.