Antibody Responses to SARS-CoV-2 Infection—Comparative Determination of Seroprevalence in Two High-Throughput Assays versus a Sensitive Spike Protein ELISA

Robust assay development for SARS-CoV-2 serological testing requires assessment of asymptomatic and non-hospitalised individuals to determine if assays are sensitive to mild antibody responses. Our study evaluated the performance characteristics of two high-throughput SARS-CoV-2 IgG nucleocapsid assays (Abbott Architect and Roche) and The Binding Site (TBS) Anti-Spike IgG/A/M ELISA kit in samples from healthcare workers (HCWs). The 252 samples were collected from multi-site NHS trusts and analysed for SARS-CoV-2 serology. Assay performance was evaluated between these three platforms and ROC curves were used to redefine the Abbott threshold. Concordance between Abbott and TBS was 66%. Any discrepant results were analysed using Roche, which showed 100% concordance with TBS. Analysis conducted in HCWs within 58 days post-PCR result demonstrated 100% sensitivity for both Abbott and Roche. Longitudinal analysis for >100 days post-PCR led to sensitivity of 77.2% and 100% for Abbott and Roche, respectively. A redefined Abbott threshold (0.64) increased sensitivity to 90%, producing results comparable to TBS and Roche. The manufacturer’s threshold set by Abbott contributes to lower sensitivity and elevated false-negative occurrences. Abbott performance improved upon re-optimisation of the cut-off threshold. Our findings provided evidence that TBS can be used as bespoke alternative for SARS-CoV-2 serology analysis where high-throughput platforms are not feasible on site.

Development of Dermatological Ointment based on Aloe arborescens juice

The purpose of this study is to select the optimal ointment base for the creation of a soft dosage form, to develop methods for standardizing dermatological ointment based on Aloe arborescens juice and to study antibacterial activity. The choice of the optimal ointment base, ensuring the maximum therapeutic effect of the ointment, was made. Ointments were prepared in accordance with the physical-chemical properties of the components of the basics. The criterion for evaluating the effectiveness of the used ointment bases was the degree of release of the active substances (anthracene derivatives). During the studies, antimicrobial activity was determined in the in vitro experiment. The comparative determination of the antimicrobial activity of ointment bases and juice of Aloe arborescens was performed by direct diffusion into agar. To develop the method of quantitative determination, the absorption spectra of Aloe arborescens juice and ointment extraction with 60% ethyl alcohol were studied. The optical density of the solution on the spectrophotometer at a wavelength of 396nm was measured. The quantitative content of the total active substances in the ointment, calculated on barbaloin was determined by using UV spectrophotometry.

ANTI-MALARIAL EFFECTS OF FIVE TRADITIONAL NIGERIAN MEDICINAL PLANT EXTRACTS ON PLASMODIUM BERGHEI-INFECTED RATS

This work focusses on comparative determination of the effects of plant extracts: bitter leaf (BL), sour lime (SL), grape (G), pawpaw (PP) and unripe pineapple (UPA) in female rats induced into malaria with Plasmodium berghei. Thirty female rats weighing 120-160 g were allotted into five groups (n=6). Group A (negative control) were infected but not treated. Animals in Groups B–E which were infected were given 500 mg/kg body weight (BW) of malanter DS (reference antimalarial drug), 500 mg/kg BW of BL, 250 mg/kg BW each of SL and BL as well as 250 mg/kg BW each of G, PP and UPA. Treatment was done orally once daily for 14 days after which a few related analyses were carried out. Before treatment, parasitemia count of animals in groups B-E was substantially (p<0.05) higher when juxtaposed with group A. AST and ALT activities was substantively (p<0.05) elevated in group B-E when matched with group A. Plasmodium berghei induction notably (p<0.05) lowered white blood cell (WBC) and monocyte (Mono) levels at all groups. After 7 days of treatment, the extracts and drug which appreciably (p<0.05) lowered plasmodium count, RBC, WBC, PCV, Hb, Plat, Lymph, Mono, Granul levels did not meaningfully (p>0.05) affect the activities of ALP, AST and ALT. After 14 days of treatment, the extracts and drug exceptionally (p<0.05) reduced plasmodium count, WBC and ALP activity at all groups. These results give suggestive evidence that the plant extracts either singly or combined, could be a promising anti-plasmodial candidate.

PECULIARITIES OF SARS-COV-2 NUCLEOCAPSID IN CHILDREN DURING THE COVID-19 EPIDEMIC OF 2020

The aim of the study is to summarize the results of a study of seroprevalence of children to SARS-CoV-3, obtained during the implementation of the Rospotrebnadzor program to assess seroprevalence to the NC antigen SARS-CoV-2 of the population of 26 regions of the Russian Federation, conducted during the COVID-19 epidemic in 2020. Research methods: the study of seroprevalence in 26 model territories of the Russian Federation was carried out according to a unified methodology developed by Rospotrebnadzor with the participation of the St. Petersburg Pasteur Institute of Epidemiology and Microbiology. The method provided for the formation of a group of volunteers in a model federative entity, including children aged 1–17 years, in which the presence of antibodies to the SARS-CoV-2 nucleocapsid was determined in venous blood plasma by the enzyme-linked immunosorbent assay (ELISA). The examination of volunteers was carried out in 3 stages: June-August, September-October, December. Results: the study found that in most of the areas surveyed, children had a higher level of seroprevalence than adults. It is shown that high seroprevalence is accompanied by statistically significant decrease in morbidity (p0.05). The analysis of seroprevalence at all three stages revealed at least 3 variants of its dynamics: 1) continuous growth of seroprevalence in parallel with the development of the epidemic process; 2) an episodic change in the periods of increase and decrease in the level of seroprevalence; 3) a continuous decrease in seroprevalence at the level of the epidemic process. Comparative determination of seroconversion levels in three age groups – 1–6, 7–13 and 14–17 years – revealed no statistically significant differences between these age groups have been identified. Conclusion: children aged 1–17 years in most of the surveyed territories of the Russian Federation have a higher seroprevalence to SARS-CoV2 than adults. The increase in seroprevalence in children is accompanied by a decrease in the incidence of COVID-19.