Mutations on the FG surface loop of human papillomavirus type 16 major capsid protein affect recognition by both type-specific neutralizing antibodies and cross-reactive antibodies.

The aim of this study was to further characterize the conformational neutralizing epitopes present on the surface-exposed FG loop of human papillomavirus (HPV) type 16 L1 major capsid protein. We have generated previously two chimeric L1 proteins by insertion of a foreign peptide encoding an epitope of the hepatitis B core (HBc) antigen within the FG loop. In addition, three other chimeric L1 proteins were obtained by replacing three different FG loop sequences by the HBc motif and three others by point mutations. All these chimeric L1 proteins retained the ability to self-assemble into virus-like particles (VLPs), with the exception of the mutant with substitution of the L1 sequence 274-279 by the HBc motif. The eight chimeric VLPs were then analyzed for differential reactivity with a set of six HPV-16 and HPV-31 monoclonal antibodies that bound to conformational and linear epitopes. The binding patterns of these monoclonal antibodies confirmed that the FG loop contained or contributed to neutralizing conformational epitopes. The results obtained suggested that the H31.F7 antibody, an anti-HPV-31 cross-reacting and neutralizing antibody, recognized a conformational epitope situated before the 266-271 sequence. In addition, H16.E70 neutralizing antibody reactivity was reduced with L1 VLPs with an Asn to Ala point mutation at position 270, suggesting that Asn is a part of the epitope recognized by this antibody. This study contributes to the understanding of the antigenic structure of HPV-16 and -31 L1 proteins by confirming that the FG loop contributes to neutralizing epitopes and suggesting the existence of both type-specific and cross-reactive conformational epitopes within the FG loop

Morphofunctional interactions between galanin and GnRH-containing neurones in the diencephalon of the ewe. The effect of oestradiol

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Morphological relationships between galanin containing fibers and gonadotropin releasing-hormone containing neurones in the sheep preoptic aera

International audienc

La microscopie confocale pour l'étude des interactions cellulaires dans le système nerveux central : relations morphofonctionelles entre les neurones à GnRH et les neurones à galanine

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La composition et la structure de la zone pellucide influencent-elles la pénétration des spermatozoïdes dans l'ovocyte?

National audienc

Innervation des neurones à GnRH par la somatostatine chez la brebis: Etude immunohistochimique

National audienc

Comparison of the composition and morphology of the zona pellucida of equine and porcine oocytes

National audienc

Etude des mécanismes de la fécondation dans l'espèce équine par une approche comparative entre les modèles équin et porcin.

National audienc

New insights into the mechanisms of fertilization: comparison of the fertilization steps, composition, and structure of the zona pellucida between horses and pigs

International audienceThe mechanism of fertilization remains largely enigmatic in mammals. Most studies exploring the molecular mechanism underlying fertilization have been restricted to a single species, generally the mouse, without a comparative approach. However, the identification of divergences between species could allow us to highlight key components in the mechanism of fertilization. In the pig, in vitro fertilization (IVF) and polyspermy rates are high, and spermatozoa penetrate easily through the zona pellucida (ZP). In contrast, IVF rates are low in the horse, and polyspermy is scarce. Our objective was to develop a comparative strategy between these two divergent models. First, we compared the role of equine and porcine gametes in the following five functions using intraspecific and interspecific IVF: ZP binding, acrosome reaction, penetration through the ZP, gamete fusion, and pronucleus formation. Under in vitro conditions, we showed that the ZP is a determining element in sperm-ZP attachment and penetration, whereas the capacity of the spermatozoa is of less importance. In contrast, the capacity of the spermatozoa is a key component of the acrosome reaction step. Second, we compared the composition and structure of the equine and porcine ZP. We observed differences in the number and localization of the ZP glycoproteins and in the mesh-like structure of the ZP between equine and porcine species. These differences might correlate with the differences in spermatozoal attachment and penetration rates. In conclusion, our comparative approach allows us to identify determining elements in the mechanism of fertilization