Performance of the ImmuView and BinaxNOW assays for the detection of urine and cerebrospinal fluid Streptococcus pneumoniae and Legionella pneumophila serogroup 1 antigen in patients with Legionnaires' disease or pneumococcal pneumonia and meningitis.

The performances of the ImmuView Streptococcus pneumoniae (Sp) and Legionella pneumophila (Lp) urinary antigen test were compared to that of the BinaxNOW Sp and Lp assays, using frozen urine from 166 patients with Legionnaires' disease (LD) and 59 patients with pneumococcal pneumonia. Thirty Sp-positive or contrived cerebrospinal fluids (CSF) were also tested. Test specimens were collected and tested at different sites, with each site testing unique specimens by technologists blinded to expected results. No significant differences in test concordances were detected for the ImmuView and BinaxNOW assays for the Sp or Lp targets for urine from patients with pneumococcal pneumonia or LD when performance from both sites were combined. At one of two test sites the ImmuView Lp assay was more sensitive than the BinaxNOW assay, with no correlation between test performance and Lp serogroup 1 monoclonal type. Urines from six of seven patients with LD caused by Legionella spp. bacteria other than Lp serogroup 1 were negative in both assays. Both tests had equivalent performance for Sp-positive CSF. The clinical sensitivities for pneumococcal pneumonia were 88.1 and 94.4% for the ImmuView and Binax assays, and 87.6 and 84.2% for the Lp assays, respectively. Test specificities for pneumococcal pneumonia were 96.2 and 97.0% for the ImmuView and Binax assays, and 99.6 and 99.1% for the Lp assays. Both assays were highly specific for Sp in pediatric urines from children with nasopharyngeal colonization by the bacterium. ImmuView and BinaxNOW assay performance was equivalent in these studies

Prevalence of SARS-CoV-2 antibodies in Denmark: nationwide, population-based seroepidemiological study.

Seroprevalence studies have proven an important tool to monitor the progression of the coronavirus disease 2019 (COVID-19) pandemic. We present results of consecutive population-based seroprevalence surveys performed in Denmark in 2020. In spring, late summer and autumn/winter of 2020, invitation letters including a questionnaire covering symptoms were sent to representative samples of the population above 12 years and to parents of children below 18 years in the sample. Blood samples were analysed for total Ig and seroprevalence estimates per population segment were calculated and compared to other surveillance parameters. Based on 34 081 participants (participation rate 33%), seroprevalence estimates increased from 1.2% (95%CI: 0.3-1.9%) in May to 4.1% (95%CI: 3.1-4.9%) in December 2020. Seroprevalence estimates were roughly three times higher in those aged 12-29 years compared to 65 + and higher in metropolitan municipalities. By December 2020, 1.5% of the population had tested positive by RT-PCR. Infected individuals in older age groups were hospitalised several fold more often than in younger. Amongst seropositives, loss of taste/smell were the more specific symptoms, 32-56% did not report any symptoms. In more than half of seroconverted families, we did not see evidence of transmission between generations. Seroprevalence increased during 2020; adolescents were primarily infected in the autumn/winter. Denmark has a high per capita test rate; roughly one undiagnosed infection of SARS-CoV-2 were estimated to occur for each diagnosed case. Approximately half were asymptomatically infected. The epidemic appears to have progressed relatively modestly during 2020 in Denmark

Differences in epitope-specific antibodies to pertussis toxin after infection and acellular vaccinations

Objectives: Pertussis toxin (PT) is a component of all acellular pertussis vaccines. PT must be detoxified to be included in acellular vaccines, which results in conformational changes in the functional epitopes of PTs. Therefore, induced epitope-specific antibodies to PT may vary after vaccinations or natural infections, and this information could reveal biomarkers implicated for protection and successful immunisation. Methods: Pertussis toxin epitope-specific antibodies in sera from 152 vaccinated children and 72 serologically confirmed patients were tested with a blocking ELISA, based on monoclonal antibodies that target protective PT epitopes. Results: All study groups induced considerable antibody titres to subunit 1 (S1). Of interest, S3 7E10-specific antibodies were present in patients, but not after vaccinations (P < 0.001). The impact of glutaraldehyde treatment of PT was visible on epitope 1D7 (S1), whereas epitopes 1B7 (S1) and 10D (S1) were more preserved. Antibodies to these epitopes were higher after three primary vaccine doses than after a single booster dose. Conclusion: The high amount of 7E10-specific antibodies in patients suggests this epitope might be functionally relevant in protection. The overall characteristics of epitope-specific antibodies are influenced by infection or vaccination background, by the used detoxification method of PT and by the amount of the toxin used in immunisation. </div

Optimization and evaluation of a live virus SARS-CoV-2 neutralization assay

Virus neutralization assays provide a means to quantitate functional antibody responses that block virus infection. These assays are instrumental in defining vaccine and therapeutic antibody potency, immune evasion by viral variants, and post-infection immunity. Here we describe the development, optimization and evaluation of a live virus microneutralization assay specific for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this assay, SARS-CoV-2 clinical isolates are pre-incubated with serial diluted antibody and added to Vero E6 cells. Replicating virus is quantitated by enzyme-linked immunosorbent assay (ELISA) targeting the SARS-CoV-2 nucleocapsid protein and the standardized 50% virus inhibition titer calculated. We evaluated critical test parameters that include virus titration, assay linearity, number of cells, viral dose, incubation period post-inoculation, and normalization methods. Virus titration at 96 hours was determined optimal to account for different growth kinetics of clinical isolates. Nucleocapsid protein levels directly correlated with virus inoculum, with the strongest correlation at 24 hours post-inoculation. Variance was minimized by infecting a cell monolayer, rather than a cell suspension. Neutralization titers modestly decreased with increasing numbers of Vero E6 cells and virus amount. Application of two different normalization models effectively reduced the intermediate precision coefficient of variance to <16.5%. The SARS-CoV-2 microneutralization assay described and evaluated here is based on the influenza virus microneutralization assay described by WHO, and are proposed as a standard assay for comparing neutralization investigations

Long-term detection of SARS-CoV-2 antibodies after infection and risk of re-infection

OBJECTIVES: To evaluate long-term sensitivity for detection of total antibodies against SARS-CoV-2 METHODS: From week 41, 2020, through week 26, 2021, all Danish blood donations were tested for SARS-CoV-2 antibodies with the Wantai assay. The results were linked with polymerase chain reaction (PCR) test results from the Danish Microbiological Database (MiBa). RESULTS: During the study period, 105,646 non-vaccinated Danish blood donors were tested for SARS-CoV-2 antibodies, and 3,806 (3.6%) had a positive PCR test before the blood donation. Among the donors with a positive PCR test, 94.2% subsequently also had a positive antibody test. The time between the positive PCR test and the antibody test was up to 15 months and there was no evidence of a decline in proportion with detectable antibodies over time. A negative serological result test was associated with a higher incidence of re-infection (Incidence Rate Ratio = 0.102 (95% confidence interval (CI): 0.039–0.262)). CONCLUSION: Among healthy blood donors, 94.2% developed SARS-CoV-2 antibodies after infection, and a lack of detectable antibodies was associated with re-infection

Risk of heart failure among individuals tested for Borrelia burgdorferi sensu lato antibodies, and serum Borrelia burgdorferi sensu lato seropositive individuals; a nationwide population-based, registry-based matched cohort study

BACKGROUND: Lyme borreliosis is a tick-borne disease caused by the bacterium Borrelia burgdorferi (Bb) sensu lato complex. Previous studies have suggested an association between Lyme borreliosis and heart failure, which have been suggested to be a possible manifestation of Lyme carditis. We aimed to investigate the risk of heart failure among individuals tested for serum Bb antibodies, and serum Bb seropositive individuals.METHODS: We performed a matched nationwide cohort study (Denmark, 1993-2020) and included 52,200 Bb seropositive individuals, and two age- and sex-matched comparison cohorts: 1) 104,400 Bb seronegative comparison cohort members, and 2) 261,000 population controls. We investigated the risk associated with 1) being tested for serum Bb antibodies, and 2) being Bb seropositive. Outcomes were: 1) a composite of heart failure, cardiomyopathy, and/or myocarditis diagnosis, and 2) redemption of cardiovascular medicine used for treatment of heart failure. We calculated short-term odds ratios (aOR) (within 1 month) and long-term hazard rates (aHR) (after 1 month) adjusted for age, sex, diabetes, pre-existing heart failure, and kidney disease.RESULTS: Compared with the population controls, individuals tested for Bb antibodies, regardless of the test result, had increased short-term risk of heart failure, cardiomyopathy, and myocarditis (aOR 8.3, 95 %CI: 6.7-10.2), and both increased short- and long-term risk of redemption of cardiovascular medicine (aOR 4.3, 95 %CI: 3.8-4.8, aHR 1.13, 95 % CI: 1.11-1.15). The Bb seropositive individuals had no increased short- or long-term risk of any outcome compared with Bb seronegative comparison cohort members.CONCLUSIONS: In conclusion, Bb antibody tests seemed to be performed in the diagnostic work-up of heart failure, but Bb seropositivity was not associated with heart failure.</p