This review summarizes the status of resolving the problem of false positive serologic results (FPSR) in Brucella serology, compiles our knowledge on the molecular background of the problem, and highlights some prospects for its resolution. The molecular basis of the FPSRs is reviewed through analyzing the components of the cell wall of Gram-negative bacteria, especially the surface lipopolysaccharide (LPS) with details related to brucellae. After evaluating the efforts that have been made to solve target specificity problems of serologic tests, the following conclusions can be drawn: (i) resolving the FPSR problem requires a deeper understanding than we currently possess, both of Brucella immunology and of the current serology tests; (ii) the practical solutions will be as expensive as the related research; and (iii) the root cause of FPSRs is the application of the same type of antigen (S-type LPS) in the currently approved tests. Thus, new approaches are necessary to resolve the problems stemming from FPSR. Such approaches suggested by this paper are: (i) the application of antigens from R-type bacteria; or (ii) the further development of specific brucellin-based skin tests; or (iii) the application of microbial cell-free DNA as analyte, whose approach is detailed in this paper.

We aimed to estimate the proportion of the population infected with SARS-CoV-2 in the first year of the pandemic. The study population consisted of outpatient adults with mild or no COVID-19 symptoms and was divided into subpopulations with different levels of exposure. Among the subpopulation without known previous COVID-19 contacts, 4143 patients were investigated. Of the subpopulation with known COVID-19 contacts, 594 patients were investigated. IgG- and IgA-seroprevalence and RT-PCR positivity were determined in context with COVID-19 symptoms. Our results suggested no significant age-related differences between participants for IgG positivity but indicated that COVID-19 symptoms occurred most frequently in people aged between 20 and 29 years. Depending on the study population, 23.4–74.0% PCR-positive people (who were symptomless SARS-CoV-2 carriers at the time of the investigation) were identified. It was also observed that 72.7% of the patients remained seronegative for 30 days or more after their first PCR-positive results. This study hoped to contribute to the scientific understanding of the significance of asymptomatic and mild infections in the long persistence of the pandemic.

We aimed to estimate the proportion of the population infected with SARS-CoV-2 in the first year of the pandemic. The study population consisted of outpatient adults with mild or no COVID-19 symptoms, and was divided into subpopulations with different levels of exposures. Of the subpopulation without known previous COVID-19 contacts 4143, of the subpopulation with known COVID-19 contacts 594 persons were investigated. IgG- and IgA-seroprevalence and RT-PCR positivity were determined in context with COVID-19 symptoms. We hope to have contributed to the understanding of the significance of the asymptomatic and mild infections in the long persistence of the pandemic.

False-positive serologic results (FPSRs) of brucellosis occur from time to time in various livestock with all the consequences (quarantine, compulsory slaughter, etc.) that follow true-positive laboratory results. A method based on the Polyacrylamide Gel Electrophoresis/Western Blot of a protein panel for resolving the FPSRs in the diagnosis of brucellosis was developed. Within the context of limited positive serum sample availability in Europe, the method successfully discriminates Brucella-positive sera from samples containing antibodies raised against infections caused by other Gram-negative bacteria causing FPSRs. An average CV% of 1.36 was determined for both repeatability and reproducibility for the whole separation mw range, and the test achieved 1.00 Diagnostic Sensitivity and 1.00 Diagnostic Specificity. The method with pre-prepared WB panels provides a rapid (less than 3 h), easily standardizable, and validatable alternative to existing confirmation methods. The whole WB process of the Brucella proteins and the subsequent densitometry can be accomplished with commercially available equipment, ready-to-use reagents, and open-source software, providing cost-effectiveness. The results of this study could attract broader attention, since molecular species in the 35.0–75.0 kDa range can serve as antigens in Brucella serology and the same fraction can be considered in the development of synthetic Brucella vaccines.