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Anti‐severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) seroprevalence is used to estimate the proportion of individuals within a population previously infected, to track viral transmission, and to monitor naturally and vaccine‐induced immune protection. However, in sub‐Saharan African settings, antibodies induced by higher exposure to pathogens may increase unspecific seroreactivity to SARS‐CoV‐2 antigens, resulting in false positive responses. To investigate the level and type of unspecific seroreactivitiy to SARS‐CoV‐2 in Africa, we measured immunoglobulin G (IgG), IgA, and IgM to a broad panel of antigens from different pathogens by Luminex in 602 plasma samples from African and European subjects differing in coronavirus disease 2019, malaria, and other exposures. Seroreactivity to SARS‐CoV‐2 antigens was higher in prepandemic African than in European samples and positively correlated with antibodies against human coronaviruses, helminths, protozoa, and especially Plasmodium falciparum. African subjects presented higher levels of autoantibodies, a surrogate of polyreactivity, which correlated with P. falciparum and SARS‐CoV‐2 antibodies. Finally, we found an improved sensitivity in the IgG assay in African samples when using urea as a chaotropic agent. In conclusion, our data suggest that polyreactive antibodies induced mostly by malaria are important mediators of the unspecific anti‐SARS‐CoV‐2 responses, and that the use of dissociating agents in immunoassays could be useful for more accurate estimates of SARS‐CoV‐2 seroprevalence in African settings. [ABSTRACT FROM AUTHOR]

Background: Soil-transmitted helminths (STH), Schistosoma spp. and Plasmodium falciparum are parasites of major public health importance and co-endemic in many sub-Saharan African countries. Management of these infections requires detection and treatment of infected people and evaluation of large-scale measures implemented. Diagnostic tools are available but their low sensitivity, especially for low intensity helminth infections, leaves room for improvement. Antibody serology could be a useful approach thanks to its potential to detect both current infection and past exposure. Methodology: We evaluated total IgE responses and specific-IgG levels to 9 antigens from STH, 2 from Schistosoma spp., and 16 from P. falciparum, as potential markers of current infection in a population of children and adults from Southern Mozambique (N = 715). Antibody responses were measured by quantitative suspension array Luminex technology and their performance was evaluated by ROC curve analysis using microscopic and molecular detection of infections as reference. Principal findings: IgG against the combination of EXP1, AMA1 and MSP2 (P. falciparum) in children and NIE (Strongyloides stercoralis) in adults and children had the highest accuracies (AUC = 0.942 and AUC = 0.872, respectively) as markers of current infection. IgG against the combination of MEA and Sm25 (Schistosoma spp.) were also reliable markers of current infection (AUC = 0.779). In addition, IgG seropositivity against 20 out of the 27 antigens in the panel differentiated the seropositive endemic population from the non-endemic population, suggesting a possible role as markers of exposure although sensitivity could not be assessed. Conclusions: We provided evidence for the utility of antibody serology to detect current infection with parasites causing tropical diseases in endemic populations. In addition, most of the markers have potential good specificity as markers of exposure. We also showed the feasibility of measuring antibody serology with a platform that allows the integration of control and elimination programs for different pathogens. Author summary: Parasitic worms and Plasmodium falciparum, the causal agent of malaria, are among the most relevant parasitic diseases of our time and efforts are under way for their control and, ultimately, elimination. An accurate diagnosis is relevant for case management, but also allows calculating the prevalence and evaluating the effectiveness of treatment and control measures. Unfortunately, current diagnostic methods for parasitic worms are not optimal and many infections remain undetected. As for P. falciparum, current diagnostic techniques are satisfactory but do not allow for ascertaining exposure, which is relevant for evaluating control measures. Here we investigated the utility of measuring antibodies to these parasites as a diagnostic method. Our results indicate that it is possible to detect current infection with parasitic worms and P. falciparum using antibody detection with a moderate to high accuracy. We also show that antibodies against the antigens in this study have potential as markers of exposure. Importantly, we used a platform that allows for the simultaneous detection of immunoglobulins to different parasites, which would be extremely useful as a tool to integrate control and elimination programs for several pathogens. [ABSTRACT FROM AUTHOR]

BACKGROUND: Emerging evidence links ambient air pollution with coronavirus 2019 (COVID-19) disease, an association that is methodologically challenging to investigate. OBJECTIVES: We examined the association between long-term exposure to air pollution with SARS-CoV-2 infection measured through antibody response, level of antibody response among those infected, and COVID-19 disease. METHODS: We contacted 9,605 adult participants from a population-based cohort study in Catalonia between June and November 2020; most participants were between 40 and 65 years of age. We drew blood samples from 4,103 participants and measured immunoglobulin M (IgM), IgA, and IgG antibodies against five viral target antigens to establish infection to the virus and levels of antibody response among those infected. We defined COVID-19 disease using self-reported hospital admission, prior positive diagnostic test, or more than three self-reported COVID-19 symptoms after contact with a COVID-19 case. We estimated prepandemic (2018–2019) exposure to fine particulate matter [PM with an aerodynamic diameter of =2.5 lm (PM2.5)], nitrogen dioxide (NO2), black carbon (BC), and ozone (O3) at the residential address using hybrid land-use regression models. We calculated log-binomial risk ratios (RRs), adjusting for individual- and area-level covariates. RESULTS: Among those tested for SARS-CoV-2 antibodies, 743 (18.1%) were seropositive. Air pollution levels were not statistically significantly associated with SARS-CoV-2 infection: Adjusted RRs per interquartile range were 1.07 (95% CI: 0.97, 1.18) for NO2, 1.04 (95% CI: 0.94, 1.14) for PM2.5, 1.00 (95% CI: 0.92, 1.09) for BC, and 0.97 (95% CI: 0.89, 1.06) for O3. Among infected participants, exposure to NO2 and PM2.5 were positively associated with IgG levels for all viral target antigens. Among all participants, 481 (5.0%) had COVID-19 disease. Air pollution levels were associated with COVID-19 disease: adjusted RRs = 1.14 (95% CI: 1.00, 1.29) for NO2 and 1.17 (95% CI: 1.03, 1.32) for PM2.5. Exposure to O3 was associated with a slightly decreased risk (RR = 0.92; 95% CI: 0.83, 1.03). Associations of air pollution with COVID-19 disease were more pronounced for severe COVID-19, with RRs = 1.26 (95% CI: 0.89, 1.79) for NO2 and 1.51 (95% CI: 1.06, 2.16) for PM2.5. DISCUSSION: Exposure to air pollution was associated with a higher risk of COVID-19 disease and level of antibody response among infected but not with SARS-CoV-2 infection. [ABSTRACT FROM AUTHOR]

Serological diagnostic of the severe respiratory distress syndrome coronavirus 2 (SARS-CoV-2) is a valuable tool for the determination of immunity and surveillance of exposure to the virus. In the context of an ongoing pandemic, it is essential to externally validate widely used tests to assure correct diagnostics and epidemiological estimations. We evaluated the performance of the COVID-19 ELISA IgG and the COVID-19 ELISA IgM/A (Vircell, S.L.) against a highly specific and sensitive in-house Luminex immunoassay in a set of samples from pregnant women and cord blood. The agreement between both assays was moderate to high for IgG but low for IgM/A. Considering seropositivity by either IgG and/or IgM/A, the technical performance of the ELISA was highly imbalanced, with 96% sensitivity at the expense of 22% specificity. As for the clinical performance, the negative predictive value reached 87% while the positive predictive value was 51%. Our results stress the need for highly specific and sensitive assays and external validation of diagnostic tests with different sets of samples to avoid the clinical, epidemiological and personal disturbances derived from serological misdiagnosis. [ABSTRACT FROM AUTHOR]

Development of SARS-CoV-2 reagents was partially supported by the NIAID Centers of Excellence for Influenza Research and Surveillance (CEIRS) contract HHSN272201400008C. The Funding section now reads: "This study was partially funded by the KidsCorona Child and Mother COVID-19 OpenData and Biobank Initiative from Hospital Sant Joan de Déu (Stavros Niarchos Foundation, Santander Foundation and others), LaCaixa Foundation, Sant Pau Research Institute, ISGlobal and Fundació Privada Daniel Bravo Andreu, Barcelona, Spain. The original article can be found online at https://doi.org/10.1038/s41598-021-98296-y. [Extracted from the article]

It was carried out a comparative study about the levels of elicited antibodies in mice by three serial batches of vaccines that had been produced in the Plant of Production of the Finlay Institute with a commercial vaccine ("Typhim Vi" from the Pasteur-Merieux Laboratories), through an immunoenzymatic test (ELISA of indirect type); it was obtained as result that there was not significant statistical differences between the levels of elicited antibodies by the vaccine batches produced in the Finlay Institute and the batch of reference vaccine. It was appreciated a significant increase of the levels of antibodies at 28 days in the vaccinated mice at compare with the controls, achieving a 100% of seroconversion for each one of the evaluated batches. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa constitutes one of the opportunistic pathogenic agents with higher frequency of isolation in the different infectious processes; so it is recognized as a great health problem worldwide. As neither a high-effective medicine nor available vaccines exist against this bacterium, a therapy with commercial polyvalent immunoglobulins is used which combined with antibiotics help to eliminate the infection, although preparations available at the market do not contain concentrations of specific antibodies sufficiently high against a certain microorganism. In this work, evaluation of an anti Pseudomonas aeruginosa immunoglobulin for therapeutic use was carried out in an animal model by a challenge assay with a virulent strain. Dose and administration route as well as the prophylactic or therapeutic value of the antibodies were evaluated. This gammaglobulin turned out to be protective in animals showing a survival of about 75?% compared to the non- protected control group. The carrier state can be also eliminated in infected individuals. [ABSTRACT FROM AUTHOR]

The epidemiological markers (sero-groups, sero-types, sub-types, immuno-types) of 429 invasive strains isolated in Cuba during 20 years (1982-2002) were investigated. Based on the behavior of the Meningococcal Disease (MD) incidence in the investigated period, the strains were distributed in two stages: epidemic and post-epidemic. The epidemic stage involved 279 strains isolated between 1982 and 1992 and the postepidemic one included 150 isolations carried out between 1993 and 2002. All of them were seeded in Mueller Hinton Agar with fetal bovine serum (5%) and incubated for 24-48 hours, 37 0C, in humid atmosphere with 5% of C02. The identification of sex, species and sero-group was performed using conventional methods; characterization of sero/sub-types and immuno-types was carried out using the immuno-enzimatic test (ELISA) of whole cells with monoclonal antibodies. Serogroup B (97,90%) prevailed in both stages: epidemic (96.77%) and post-epidemic (100%). However, sero-group C (1.43%) and non-grouping strains (1,8%) were only observed in the isolations of the epidemic stage. The other prevailing markers were: serotype 4 (86.48%), subtype P1.19,15 (78.32%), immuno-type L3,7,9 (90.2%) which showed similar figures in both periods. Phenotype B:4:P1.19,15: L3,7,9 (69,69%) prevailed, although, in the post-epidemic stage (77.34%), the percentage was higher than that of the epidemic one (65.66%) (p<0.05). A higher diversity of phenotypic associations was also observed in the strains of this period. Results obtained from this phenotypic characterization of Neisseria meningitidis strains isolated from ill persons provide valuable data to the study, prevention and succesful control of the MD in Cuba. [ABSTRACT FROM AUTHOR]

The objetive of the present work was to carry out a study the kinetics of neutralizing antibodies in Beagle dogs immunizated with cell culture rabies vaccine. For the assays, 20 animals 6 month old of the both sex were ditributed in 4 groups. The animales were immunizated with two types of rabies vaccine: A suckling mouse brain inactivated with ultraviolet-light irradiation and two batches (0595 and 0695)of a tissue culture vaccine, elaborated with a viral suspension of Pasteur Virus (PV) strain grown in BHK-21 cell culture and inactivated with 2-Bromoetilamina. The first group received the suckling mouse brain vaccine, the second and the third groups received cell culture batch 0695 and batch 0695 respectively and the fourth was the control group. The animals were immunized intamuscularly with a single dose of 2 mL. Blood was collected in days 0, 7, 14, 21, 28, 180, 360 and analyzed by seroneutralization in mice. Dogs of the first group showed 40% seropositivity at the end of the test, whereas dogs of the second and groups showed 80% of seropositivity. The results demonstrated the high immunizing power of the cell culture vaccine. [ABSTRACT FROM AUTHOR]