The reason(s) why human antibodies raised against hepatitis C virus (HCV) E2 epitopes do not offer protection against multiple viral infections may be related to either genetic variations among viral strains particularly within the hypervariable region-1 (HVR-1), low titers of anti E2 antibodies or interference of non neutralizing antibodies with the function of neutralizing antibodies. This study was designed to assess the immunogenic properties of genetically conserved peptides derived from the C-terminal region of HVR-1 as potential therapeutic and/or prophylactic vaccines against HCV infection. Goats immunized with E2-conserved synthetic peptides termed p36 (a.a 430-446), p37(a.a 517-531) and p38 (a.a 412-419) generated high titers of anti-p36, anti-p37 and anti-P38 antibody responses of which only anti-p37 and anti-p38 were neutralizing to HCV particles in sera from patients infected predominantly with genotype 4a. On the other hand anti-p36 exhibited weak viral neutralization capacity on the same samples. Animals super-immunized with single epitopes generated 2 to 4.5 fold higher titers than similar antibodies produced in chronic HCV patients. Also the studied peptides elicited approximately 3 fold increase in cell proliferation of specific antibodysecreting peripheral blood mononuclear cells (PBMC) from immunized goats. These results indicate that, besides E1 derived peptide p35 (a.a 315-323) described previously by this laboratory, E2 conserved peptides p37 and p38 represent essential components of a candidate peptide vaccine against HCV infection.

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Staphylococcus aureus (S. aureus) is a versatile bacterium which exhibits multiple antibiotic resistances. To ameliorate the undesirable diseases causing potential, there is a need to design a protective vaccine capable of stimulating immune response against this pathogen. In a similar study in our laboratory, reverse vaccinology approach was used to nominate potential vaccine candidate genes against S. aureus. Zinc Metalloproteinase Aureolysin (aur) gene was one of the nominated genes based on that previously published in-silico study. The objective of this study is the cloning, expression, purification of aur gene and testing the aur protein reactivity with serum antibodies collected from groups of human patients with confirmed Staphylococcal disease. Cloning was done in pH6HTN His6HaloTag® vector and it was expressed in E. coli BL21 (DE3) using these conditions; 0.5 mM Isopropyl β-D-1-thiogalactopyranoside (IPTG) for 4 h at 37°C. Purification was carried out by Immobilized Metal Affinity Chromatography (IMAC). The his-tag aur protein was detected at ~86 KDa as a single band after western blot assay and was successfully reacted with antibodies obtained from humans infected with S. aureus. The results encourage further testing of aur protein as a potential vaccine candidate for S. aureus.