Optimization of vitellogenin latex agglutination (VTG-LAT), for field determination of male fish contamination by estrogen mimics: Study of adsorption and agglutination profiles

A latex agglutination test was performed with particles coated by monoclonal antibodies (mAbs) specific of vitellogenin (VTG). This test was able to detect the abnormal VTG production by immature or male fish contaminated by estrogen mimics. These compounds induce abnormalities in the reproductive system of male fish, which lead to a total or partial male feminization. Ultimately, these alterations could lead to a disappearance of the total contaminated fish population. The purpose of this research was to optimize the mAbs adsorption on surface particles (pH; initial mAbs concentration) and the agglutination profiles. The optimal adsorption pH was found closed to the mAbs IEP. Concerning the initial mAbs concentration, the optimal concentration was ≅500 mg L−1. Above this concentration, the non-adsorbed mAbs amount was important. Moreover, in the case of F4/9/1, a decreasing of the mAbs adsorbed was observed. By contrast, for G10/5/1 and F4/8/1, the mAbs adsorption continues increasing. The presence of two positive slopes means a change of mAbs conformation or orientation. Finally, agglutination profiles obtained with non-treated vitellogenic females, estradiol-treated males and vitellogenic females plasma let us to suppose that two VTG proteins are recognized: one of them in vitellogenic females and the second one in treated animals.