Dengue virus seroprevalence study in Bangphae district, Ratchaburi, Thailand: A cohort study in 2012-2015

Background To determine the seroprevalence and transmission dynamics of dengue virus (DENV), age-stratified longitudinal serological surveys were conducted in Bangphae district, Ratchaburi province, Thailand, for 3 years between April 2012 and April 2015. Methodology The surveys enrolled 2012 healthy children and adults between 1 and 55 years-of-age, and a longitudinal serosurvey of six repeated bleeds of the same cohort of individuals was conducted every 8 months for the first 2 years (M0, M8, M16) and every half a year (M24, M30, M36) for the rest of the study period. All samples were tested using in-house indirect sandwich dengue IgG ELISA to determine DENV antibody titer, and 640 paired samples which showed rising of DENV IgG titers in paired serum were further tested using in-house neutralization assay, Plaque Reduction Neutralization Test (PRNT50). Principal findings When compared against the gold standard based on the results of PRNT50, sensitivity and specificity of indirect ELISA were found to be both about 85%. The overall DENV IgG positivity determined by ELISA was 74.3% in 2012 and increased to 79.4% by the final sample collection in 2015. In our study sample, more than 98% of subjects older than 25 years were found to be seropositive. Among 518 IgG negative subjects at enrollment, the seroconversion rates were measured in paired bleeds; the rates (between successive visits, approximately 6 months) ranged between 4.8% (between M16 and M24) and 14.7% (between M0 and M8). The dominant serotype of primary DENV infection cases based on seroconversion was identified from the PRNT results and it was DENV-2. Conclusions Our study documented high levels of seroprevalence and rate of transmission. Given the importance of the serostatus and disease burden in consideration for dengue vaccine introduction, our data could be used in decision-making on implementation of various dengue control and preventive measures.

Serum anti-Spike antibody titers before and after heterologous booster with mRNA-1273 SARS-CoV-2 vaccine following two doses of inactivated whole-virus CoronaVac vaccine

Background: The inactivated whole-virus vaccine CoronaVac (SinoVac) is the COVID-19 vaccine most administered worldwide. However, data on its immunogenicity and reactogenicity to heterologous boosting with mRNA vaccines are lacking. Methods: In a cohort of hospital staff in Jakarta, Indonesia, who received two-dose CoronaVac six months prior (median 190 days, IQR165-232), we measured anti-Spike IgG titers on paired serum samples taken before and 28 days after a 100μg mRNA-1273 (Moderna) booster. We performed correlations and multivariable ordinal regressions. Findings: Among 304 participants, the median age was 31 years (range 21-59), 235 (77.3%) were women, 197 (64.8%) had one or more previous SARS-CoV-2 infections (including 155 [51.0%] who had a post-CoronaVac breakthrough infection. Pre-boost IgG titers correlated negatively with the time since the latest documented virus exposure (either by the second CoronaVac or SARS-CoV-2-infection whichever most recent). Previous SARS-CoV-2 infection and a longer time interval between second vaccine and mRNA-1273 boost were associated with a higher pre-boost IgG titer. Post-booster, the median IgG titer increased 9.3-fold, from 250 (IQR32-1389) to 2313 (IQR1226-4324) binding antibody units (BAU/mL) (p<0.001). All participants, including seven whose pre-boost IgG was below assay detection limits, became seropositive and all reached a substantial post-boost titer (≥364 BAU/mL). Post-boost IgG was not associated with pre-boost titer or previous SARS-CoV-2 infection. Booster reactogenicity was acceptable, with 7.9% of participants experiencing short-lived impairment of activities of daily living (ADL). Interpretation: A heterologous, high-dose mRNA-1273 booster after two-dose CoronaVac was highly immunogenic and safe, including in those most in need of improved immunity. Funding: Wellcome Trust, UK Keywords SARS-CoV-2; COVID-19; inactivated vaccine; CoronaVac; mRNA-1273; antibodies

Salivary Ferritin Changes in Patients with COVID-19

High ferritin serum levels can be found in patients with macrophage activation syndrome, and increased serum ferritin due to cytokine storm have been reported in severe COVID-19 patients. Saliva is being increasingly used in COVID-19 tests as a diagnostic sample for virus detection and quantification. This study aimed to evaluate the possible changes in ferritin in saliva in COVID-19 patients. In addition, the effects of different inactivation SARS-CoV-2 treatments in ferritin measurements in saliva, the correlation between ferritin in saliva and serum, and the possible effects of correction of ferritin values by total protein were assessed. Ferritin was measured in saliva from healthy (n = 30) and COVID-19 (n = 65) patients with severe, (n = 18) or mild (n = 47) disease, depending on the need for nasal flow oxygen or assisted respiration. Ferritin was also measured in paired serum and saliva samples (n = 32) from healthy and COVID-19 patients. The evaluated inactivation protocols did not affect the assay’s results except the addition of 0.5% SDS. Significantly higher ferritin was found in the saliva of COVID-19 patients (median; 25–75th percentile) (27.75; 9.77–52.2 µg/L), compared with healthy controls (4.21; 2.6–8.08 µg/L). Individuals with severe COVID-19 showed higher ferritin values in saliva (48.7; 18.7–53.9) than mild ones (15.5; 5.28–41.3 µg/L). Significant correlation (r = 0.425; p < 0.001) was found between serum and saliva in ferritin. Ferritin levels were higher in COVID-19 patients in serum and saliva, and the highest values were found in those patients presenting severe symptomatology. In conclusion, ferritin in saliva has the potential to be a biomarker to evaluate severity in patients with COVID-19.

Evaluation of SARS-CoV-2 Antibody Point of Care Devices in the Laboratory and Clinical Setting

SARS-CoV-2 Antibody tests have been marketed to diagnose previous SARS-CoV-2 infection and as a test of immune status. There is a lack of evidence on the performance and clinical utility of these tests. We aimed to carry out an evaluation of 14 point of care (POC) SARS-CoV-2 antibody tests. Serum from participants with previous RT-PCR (Real-Time Polymerase chain reaction) confirmed SARS-CoV-2 infection and pre-pandemic controls were used to determine specificity and sensitivity of each POC device. Changes in sensitivity with increasing time from infection were determined on a cohort of participants. Corresponding neutralising antibody status was measured to establish whether the detection of antibodies by the POC device correlated with immune status. Paired capillary and serum samples were collected to ascertain whether POC devices performed comparably on capillary samples. Sensitivity and specificity varied between the POC devices and in general did not meet the manufacturers reported performance characteristics signifying the importance of independent evaluation of these tests. The sensitivity peaked at >20 days following symptoms onset however sensitivity of 3 POC devices evaluated at extended time points showed that sensitivity declined with time and this was particularly marked at >140 days post infection onset. This is relevant if the tests are to be used for sero-prevelence studies. Neutralising antibody data showed positive antibody results on POC devices did not necessarily confer high neutralising antibody titres and these POC devices cannot be used to determine immune status to the SARS-CoV-2 virus. Comparison of paired serum and capillary results showed that there was a decline in sensitivity using capillary blood. This has implications in the utility of the test as they are designed to be used on capillary blood by the general population.

Efficient mucosal antibody response to SARS-CoV-2 vaccination is induced in previously infected individuals

Mucosal immune responses are critical to prevent respiratory infections but it is unclear to what extent antigen specific mucosal secretory IgA (SIgA) antibodies are induced by mRNA vaccination in humans. We analyzed, therefore, paired serum and saliva samples from study participants with and without COVID-19 at multiple timepoints before and after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination. Our results suggest that the level of mucosal SIgA responses induced by mRNA vaccination depend on pre-existing immunity. Indeed, vaccination induced only a weak mucosal SIgA response in individuals without pre-existing mucosal antibody responses to SARS-CoV-2 while SIgA induction after vaccination was efficient in COVID-19 survivors. Our data indicate that vaccinated seropositive individuals were able to swiftly induce relatively high anti-spike SIgA responses by boosting pre-existing mucosal immunity. In contrast, seronegative individuals did not have pre-existing anti-SARS-CoV-2 or cross-reacting anti-HCoV SIgA antibodies prior to vaccination, and, thus, little or no anti-SARS-CoV-2 SIgA antibodies were induced by vaccination in these individuals.

Myelin Oligodendrocyte Glycoprotein-Immunoglobulin G in the CSF

Background and ObjectiveTo investigate the clinical relevance of CSF myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG) testing in a large multicenter cohort.MethodsIn this multicenter cohort study, paired serum-CSF samples from 474 patients with suspected inflammatory demyelinating disease (IDD) from 11 referral hospitals were included. After serum screening, patients were grouped into seropositive myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD, 31), aquaporin-4-IgG-positive neuromyelitis optica spectrum disorder (AQP4-IgG + NMOSD, 60), other IDDs (217), multiple sclerosis (MS, 45), and non-IDDs (121). We then screened CSF for MOG-IgG and compared the clinical and serologic characteristics of patients uniquely positive for MOG-IgG in the CSF to seropositive patients with MOGAD.ResultsNineteen patients with seropositive MOGAD (61.3%), 9 with other IDDs (CSF MOG + IDD, 4.1%), 4 with MS (8.9%), but none with AQP4-IgG + NMOSD nor with non-IDDs tested positive in the CSF for MOG-IgG. The clinical, pathologic, and prognostic features of patients uniquely positive for CSF MOG-IgG, with a non-MS phenotype, were comparable with those of seropositive MOGAD. Intrathecal MOG-IgG synthesis, observed from the onset of disease, was shown in 12 patients: 4 of 28 who were seropositive and 8 who were uniquely CSF positive, all of whom had involvement of either brain or spinal cord. Both CSF MOG-IgG titer and corrected CSF/serum MOG-IgG index, but not serum MOG-IgG titer, were associated with disability, CSF pleocytosis, and level of CSF proteins.DiscussionCSF MOG-IgG is found in IDD other than MS and also in MS. In IDD other than MS, the CSF MOG-IgG positivity can support the diagnosis of MOGAD. The synthesis of MOG-IgG in the CNS of patients with MOGAD can be detected from the onset of the disease and is associated with the severity of the disease.Classification of EvidenceThis study provides Class II evidence that the presence of CSF MOG-IgG can improve the diagnosis of MOGAD in the absence of an MS phenotype, and intrathecal synthesis of MOG-IgG was associated with increased disability.

Neutralization of Dengue Virus Serotypes by Sera from Dengue-Infected Individuals Is Preferentially Directed to Heterologous Serotypes and Not against the Autologous Serotype Present in Acute Infection

Sequential infections of humans by the four different dengue serotypes (DENV-1–4) lead to neutralizing antibodies with group, cross, and type specificity. Virus neutralization of serotypes showed monotypic but mostly multitypic neutralization profiles due to multiple virus exposures. We have studied neutralization to heterologous, reference DENV serotypes using paired sera collected between days 6 and 37 after onset of fever. The DENV-primed neutralization profile of the first serum sample, which was monitored by a foci reduction neutralization test (FRNT), was boosted but the neutralization profile stayed unchanged in the second serum sample. In 45 of 47 paired serum samples, the predominant neutralization was directed against DENV serotypes distinct from the infecting serotype. Homologous neutralization studies using sera and viruses from the same area, 33 secondary sera from DENV-1 infected Cambodian patients and eight virus isolates from Cambodia, showed that the FRNT assay accurately predicted the lack of a predominant antibody response against the infecting DENV-1 serotype in contrast to FRNT results using the WHO set of DENV viruses. This report provides evidence that DENV-primed multitypic neutralizing antibody profiles were mainly boosted and stayed unchanged after secondary infection and that DENV neutralization was predominantly directed to heterologous DENV but not against the infecting homologous serotype.

Evaluation of Two Serological Assays for Diagnosing Zika Virus Infection

Zika virus (ZIKV) emerged and spread rapidly in South American countries during 2015. Efforts to diagnose ZIKV infection using serological tools were challenging in dengue-endemic areas because of antigenic similarities between both viruses. Here, we assessed the performance of an in-house developed IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and the plaque reduction neutralization test (PRNT) to diagnose ZIKV infection. Acute and convalescent paired serum samples from 51 patients who presented with clinical symptoms suggestive of an arbovirus illness in dengue-endemic areas of Honduras, Venezuela, Colombia and Peru were used in the assessment. Samples were tested for ZIKV, dengue and chikungunya virus using a variety of laboratory techniques. The results for the ZIKV-RNA screening and seroconversion detected by the microneutralization test were used to construct a composite reference standard. The overall sensitivity and specificity for the MAC-ELISA were 93.5% and 100.0%, respectively. Contrastingly, the overall sensitivity and specificity for the PRNT were 96.8% and 95.0%, respectively. Restricting the analysis according to IgM or neutralizing antibodies against dengue, the performances of both serological assays were adequate. The findings of this study reveal that the MAC-ELISA and PRNT would provide initial reliable laboratory diagnostic assays for ZIKV infection in dengue-endemic areas.

Simultaneous Quantification and Speciation of Trace Metals in Paired Serum and CSF Samples by Size Exclusion Chromatography–Inductively Coupled Plasma–Dynamic Reaction Cell–Mass Spectrometry (SEC-DRC-ICP-MS)

Background: Transition metals play a crucial role in brain metabolism: since they exist in different oxidation states they are involved in ROS generation, but they are also co-factors of enzymes in cellular energy metabolism or oxidative defense. Methods: Paired serum and cerebrospinal fluid (CSF) samples were analyzed for iron, zinc, copper and manganese as well as for speciation using SEC-ICP-DRC-MS. Brain extracts from Mn-exposed rats were additionally analyzed with SEC-ICP-DRC-MS. Results: The concentration patterns of transition metal size fractions were correlated between serum and CSF: Total element concentrations were significantly lower in CSF. Fe-ferritin was decreased in CSF whereas a LMW Fe fraction was relatively increased. The 400–600 kDa Zn fraction and the Cu-ceruloplasmin fraction were decreased in CSF, by contrast the 40–80 kDa fraction, containing Cu- and Zn-albumin, relatively increased. For manganese, the α-2-macroglobulin fraction showed significantly lower concentration in CSF, whereas the citrate Mn fraction was enriched. Results from the rat brain extracts supported the findings from human paired serum and CSF samples. Conclusions: Transition metals are strictly controlled at neural barriers (NB) of neurologic healthy patients. High molecular weight species are down-concentrated along NB, however, the Mn-citrate fraction seems to be less controlled, which may be problematic under environmental load.

Serological detection of SARS-CoV-2 IgG using a commercially available enzyme immunoassays on dried blood spots collected from patients

Serological testing for SARS-CoV-2 antibodies provides important research and diagnostic information relating to COVID-19 immune response and surveillance. A major challenge when addressing protection post- infection or vaccination is the difficulty of specimen collection from infants and children. Dried blood spots (DBS) collected by finger prick or heel prick are a minimally invasive sample collection alternative previously used to detect antibodies to other viruses. In this study we evaluated DBS for the detection of SARS-CoV-2 antibodies on three commercially available enzyme (EIA) and chemiluminescent (CLIA) immunoassays by analysing paired DBS and serum samples collected from 54 subjects. We demonstrate that testing of DBS samples was highly sensitive and specific, and quantitative results strongly correlated with those of paired serum. These results suggest that DBS derived blood is a viable alternative to plasma or serum for use in EIAs and CLIAs, and has particular utility as a minimally invasive collection tool for COVID-19 serological testing of infants and children.