SARS-CoV-2 Peptide Bioconjugates Designed for Antibody Diagnostics.

In the near future, the increase in the number of required tests for COVID-19 antibodies is expected to be many hundreds of millions. Obviously, this will be done using a variety of analytical methods and using different antigens, including peptides. In this work, we compare three method variations for detecting specific immunoglobulins directed against peptides of approximately 15-aa of the SARS-CoV-2 spike protein. These linear peptide epitopes were selected using antigenicity algorithms, and were synthesized with an additional terminal cysteine residue for their bioconjugation. In two of the methods, constructs were prepared where the peptide (F, function) is attached to a negatively charged hydrophilic spacer (S) linked to a dioleoylphosphatidyl ethanolamine residue (L, lipid) to create a function-spacer-lipid construct (FSL). These FSLs were easily and controllably incorporated into erythrocytes for serologic testing or in a lipid bilayer deposited on a polystyrene microplate for use in an enzyme immunoassays (EIA). The third method, also an EIA, used polyacrylamide conjugated peptides (peptide-PAA) prepared by controlled condensation of the cysteine residue of the peptide with the maleimide-derived PAA polymer which were immobilized on polystyrene microplates by physisorption of the polymer. In this work, we describe the synthesis of the PAA and FSL peptide bioconjugates, design of test systems, and comparison of the bioassays results, and discuss potential reasons for higher performance of the FSL conjugates, particularly in the erythrocyte-based serologic assay.

Efficacy of vitamin C vaginal tablets as prophylaxis for recurrent bacterial vaginosis: a randomised, double-blind, placebo-controlled clinical trial.

BACKGROUND: The aetiology of bacterial vaginosis (BV) is still unclear but it is currently considered to be a synergistic polymicrobial syndrome. BV can often arise as a chronic or recurrent disease. The reason for such recurrences is not well elucidated. Previous studies have suggested that vaginal vitamin C may be a useful treatment in reducing recurrence rate, by increasing vaginal acidification and thereby making up for the decrease in hydrogen peroxide that results from a reduction in the number of lactobacilli present. Based on the above-mentioned consideration, a study was performed that aimed to evaluate the effect of vitamin C in the prophylaxis of BV relapses. METHODS: This was a randomised, double-blind, placebo-controlled, parallel-group clinical trial. One hundred and forty-two women, after having been cured from a recent episode of BV by either metronidazole or clindamycin, were randomised to receive vitamin C (74 patients) or placebo (68 patients) as prophylaxis for six monthly cycles, starting within 24 hours of the determination of 'BV cure'. The patients applied one vaginal tablet once a day for 6 consecutive days per month after menses. RESULTS: The rate of BV recurrence during the first 3 months was considerably lower in the vitamin C group (6.8%) than in the placebo (14.7%) group. Considering a 6-month treatment period, the recurrence rate in the vitamin C group (16.2%) was significantly lower (P = 0.024) than in the placebo group (32.4%). Moreover, at the same time point, the survival analysis of Kaplan Meyer was significant in favour of the vitamin C group compared with the placebo group (P = 0.029). CONCLUSIONS: The study showed that regular use of 250 mg ascorbic acid vaginal tablets on 6 days per month for 6 months after successful treatment of bacterial vaginosis halves the risk of recurrence from 32.4% to 16.2% (P = 0.024).