Seropositive Individuals Research Articles

Status of Hepatitis B Virus Surface Antigen (HBsAg) Deposition in Renal Tissue among Glomerulonephritis Patients

Background: Hepatitis B virus (HBV) related glomerulonephritis (GN) may be found in HBV seropositive as well as seronegative patients. HBV may present in the renal tissue of such patients. Objective: The purpose of the present study was to assess status of HBsAg deposition in renal tissue among glomerulonephritis patients. Methodology: This cross-sectional study was conducted in the Department of Nephrology at Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh during the period of July 2015 to June 2016. All diagnosed GN patients both HBV seropositive and seronegative aged more than 18 years of both sexes admitted in the department of Nephrology BSMMU were taken as the study population. Serological tests both HBsAg and anti-HBc (total) were done to identify the HBV seropositive and seronegative individuals by ELISA technique and Chemiluminescense Method respectively. Renal biopsy was done percutaneously through a posterior approach. Immunohistochemistry and one core were preserved in normal saline for direct immunofluorescence (DIF). Both test tubes were sent to find out histological features and presence of HBsAg in renal biopsy tissue in Pathology Department of Bangabandhu Sheikh Mujib Medical University, Dhaka. Results: HBsAg antigen in renal tissue was found in 2 patients among 7 patients who were seropositive for both HBsAg and Anti-HBc antibody (total), 2 patients among 8 patients who were HBsAg seronegative but Anti-HBc (total) seropositive, 2 patients among 38 patients who were seronegative for both HBsAg and Anti-HBc (total). There were no patients in this study who was HBsAg seropositive but Anti HBc (total) seronegative. Total 11.3% (6 patients) of renal biopsy specimens were found to have HBsAg deposits which included 3 cases of Membranoproliferative GN and one of each of Membranous nephropathy, Mesangial proliferative GN and IgA nephropathy. Conclusion: The high rate of HBsAg deposits has been found in renal tissue among GN patients. Bangladesh Journal of Medical Microbiology, January 2022;16(1):14-18

Development of an Affordable ELISA Targeting the SARS-CoV-2 Nucleocapsid and Its Application to Samples from the Ongoing COVID-19 Epidemic in Ghana.

The true nature of the populationspread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in populations is often not fully known as most cases, particularly in Africa, are asymptomatic. Finding the true magnitude of SARS-CoV-2 spread is crucial to provide actionable data about the epidemiological progress of the disease for researchers and policymakers. This study developed and optimized an antibody enzyme-linked immunosorbent assay (ELISA) using recombinant nucleocapsid antigen expressed in-house using a simple bacterial expression system. Nucleocapsid protein from SARS-CoV-2 was expressed and purified from Escherichia coli. Plasma samples used for the assay development were obtained from GhanaianSARS-CoV-2 seropositive individuals during the pandemic, while seronegative controls were plasma samples collectedfrom blood donors before the coronavirus disease 2019 (COVID-19) pandemic. Another set of seronegative controls was collected during the COVID-19 pandemic. Antibody detection andlevels within the samples were validated using commercial kits and Luminex. Analyses were performed using GraphPad Prism, and the sensitivity, specificity and background cut-off were calculated. This low-cost ELISA (£0.96/test) assay has a high prediction of 98.9%, and sensitivity and specificity of 97% and 99%, respectively. The assay was subsequently used to screen plasma from SARS-CoV-2 RT-PCR-positive Ghanaians. The assay showed no significant difference in nucleocapsid antibody levels between symptomatic and asymptomatic, with an increase of the levels over time. This is in line with our previous publication. This study developed a low-cost and transferable assay that enables highly sensitive and specific detection of human anti-SARS-CoV-2 IgG antibodies. This assay can be modified to include additional antigens and used for continuous monitoring of sero-exposure to SARS-CoV-2 in West Africa.

SARS-CoV-2 antibody response duration and neutralization following natural infection

BackgroundThe role of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) neutralizing antibody response from natural infection and vaccination, and the potential determinants of this response are poorly understood. Characterizing this antibody response and the factors associated with neutralization can help inform future prevention efforts and improve clinical outcomes in those infected. ObjectivesThe goals of this study were to prospectively evaluate SARS-CoV-2 antibody levels and the neutralizing antibody responses among naturally infected adults and to determine demographic and behavioral factors independently associated with these responses. MethodsSerum was collected from seropositive individuals at baseline, four-weeks, and three-months following their first study visit to be evaluated for antibody levels. Detection of neutralizing antibodies was performed at baseline. Participant demographic and behavioral information was collected via web questionnaire prior to their first visit. ResultsAt baseline, higher antibody levels were associated with better neutralization capacity, with 83% of participants having detectable neutralizing antibodies. We found an age-dependent effect on antibody level and neutralization capacity with participants over 65 years having significantly higher levels. Ethnicity, heart disease, autoimmune disease, and COVID symptoms were associated with higher antibody levels, but not with increased neutralization capacity. Work environment during the pandemic correlated with increased neutralization capacity, while kidney or liver disease and traveling out of state after February 2020 correlated with decreased neutralization capacity, however neither correlated with antibody levels. ConclusionsOur data show that natural infection by SARS-CoV-2 can induce a humoral response reflected by high antibody levels and neutralization capacity.

Postinfectious and Postvaccinal Humoral Immune Response to SARS-CoV-2 in Adults: Qualitative and Quantitative Assessment

Relevance. Serological studies play an important role in assessing the spread of SARS-CoV-2 and formation of post-infection and post-vaccination immune response.The Aims aim of the study was a comparative assessment of seroprevalence and concentration of antibodies to SARS-CoV-2 at 3–6 months after infection or vaccination.Materials & Methods. For the presence of total IgM and IgG antibodies to RBD fragment of the SARS-CoV-2 S protein, the blood sera of 1331 people aged 18-70 years were examined, of which 334 had COVID-19 3–6 months before the study, 305 did not have COVID-19 and were vaccinated (using Sputnik V, Russia, or Sinopharm, PRC) 3–6 months before the study, 692 people were not ill and were not vaccinated. A quantitative assessment of IgG antibodies to the full-size S-protein of SARS-CoV-2 was performed for 435 samples.Results. The proportion of seropositive individuals 3–6 months after COVID-19 or after vaccination did not differ: 92.5% and 93.8% of the corresponding group had antibodies. Among the non-ill and unvaccinated, 45.7% also had specific antibodies, which indicates a high level of asymptomatic infection with SARS-CoV-2. The group of vaccinated was also examined immediately before the introduction of the vaccine, and 39.7% of them already had specific antibodies due to asymptomatic infection with SARS-CoV-2. The median concentration of antibodies in the group of COVID-19 was statistically significantly higher than in asymptomatically infected (50.9 AE/ml versus 29.1 AE/ml). The largest proportion of seropositive individuals (100.0%) and the highest concentration of antibodies (110 AE/ml) were detected in the group of vaccinated who had pre-existing antibodies.Conclusion. Infection with the SARS-CoV-2 is characterized by a high frequency of subclinical course. Asymptomatic infection induced a weaker immune response compared to symptomatic COVID-19 or vaccination. Hybrid immunity caused by natural infection with SARS-CoV-2 and subsequent vaccination was the most persistent and pronounced.

Therapeutically targeting the consequences of HIV-1-associated gastrointestinal dysbiosis: Implications for neurocognitive and affective alterations

Approximately 50 % of the individuals living with human immunodeficiency virus type 1 (HIV-1) are plagued by debilitating neurocognitive impairments (NCI) and/or affective alterations. Sizeable alterations in the composition of the gut microbiome, or gastrointestinal dysbiosis, may underlie, at least in part, the NCI, apathy, and/or depression observed in this population. Herein, two interrelated aims will be critically addressed, including: 1) the evidence for, and functional implications of, gastrointestinal microbiome dysbiosis in HIV-1 seropositive individuals; and 2) the potential for therapeutically targeting the consequences of this dysbiosis for the treatment of HIV-1-associated NCI and affective alterations. First, gastrointestinal microbiome dysbiosis in HIV-1 seropositive individuals is characterized by decreased alpha (α) diversity, a decreased relative abundance of bacterial species belonging to the Bacteroidetes phylum, and geographic-specific alterations in Bacillota (formerly Firmicutes) spp. Fundamentally, changes in the relative abundance of Bacteroidetes and Bacillota spp. may underlie, at least in part, the deficits in γ-aminobutyric acid and serotonin neurotransmission, as well as prominent synaptodendritic dysfunction, observed in this population. Second, there is compelling evidence for the therapeutic utility of targeting synaptodendritic dysfunction as a method to enhance neurocognitive function and improve motivational dysregulation in HIV-1. Further research is needed to determine whether the therapeutics enhancing synaptic efficacy exert their effects by altering the gut microbiome. Taken together, understanding gastrointestinal microbiome dysbiosis resulting from chronic HIV-1 viral protein exposure may afford insight into the mechanisms underlying HIV-1-associated neurocognitive and/or affective alterations; mechanisms which can be subsequently targeted via novel therapeutics.

Anti-dense fine speckled 70 (DFS70) autoantibodies: correlates and increasing prevalence in the United States.

Recent studies report high-titer anti-dense fine speckled 70 (DFS70) autoantibodies in persons with inflammatory conditions, but the clinical significance remains unclear. Our goals were to estimate anti-DFS70 autoantibody prevalence, identify correlates, and assess time trends. Serum antinuclear antibodies (ANA) were measured by indirect immunofluorescence assay on HEp-2 cells in 13,519 participants ≥12 years old from three time periods (1988-1991, 1999-2004, 2011-2012) of the National Health and Nutrition Examination Survey. ANA-positive participants with dense fine speckled staining were evaluated for anti-DFS70 antibodies by enzyme-linked immunosorbent assay. We used logistic models adjusted for survey-design variables to estimate period-specific anti-DFS70 antibody prevalence in the US, and we further adjusted for sex, age, and race/ethnicity to identify correlates and assess time trends. Women were more likely than men (odds ratio (OR)=2.97), black persons were less likely than white persons (OR=0.60), and active smokers were less likely than nonsmokers (OR=0.28) to have anti-DFS70 antibodies. The prevalence of anti-DFS70 antibodies increased from 1.6% in 1988-1991 to 2.5% in 1999-2004 to 4.0% in 2011-2012, which corresponds to 3.2 million, 5.8 million, and 10.4 million seropositive individuals, respectively. This increasing time trend in the US population (P<0.0001) was modified in some subgroups and was not explained by concurrent changes in tobacco smoke exposure. Some, but not all, anti-DFS70 antibody correlates and time trends resembled those reported for total ANA. More research is needed to elucidate anti-DFS70 antibody triggers, their pathologic or potentially protective influences on disease, and their possible clinical implications.

NK Cells from Human Cytomegalovirus-Seropositive Individuals Have a Distinct Metabolic Profile That Correlates with Elevated mTOR Signaling.

CMV can elicit adaptive immune features in both mouse and human NK cells. Mouse Ly49H+ NK cells expand 100- to 1000-fold in response to mouse CMV infection and persist for months after exposure. Human NKG2C+ NK cells also expand after human CMV (HCMV) infection and persist for months. The clonal expansion of adaptive NK cells is likely an energy-intensive process, and the metabolic requirements that support adaptive NK cell expansion and persistence remain largely uncharacterized. We previously reported that NK cells from HCMV-seropositive donors had increased maximum capacity for both glycolysis and mitochondrial oxidative phosphorylation relative to NK cells from HCMV-seronegative donors. In this article, we report an extension of this work in which we analyzed the metabolomes of NK cells from HCMV-seropositive donors with NKG2C+ expansions and NK cells from HCMV seronegative donors without such expansions. NK cells from HCMV+ donors exhibited striking elevations in purine and pyrimidine deoxyribonucleotides, along with moderate increases in plasma membrane components. Mechanistic target of rapamycin (mTOR) is a serine/threonine protein kinase that, as a part of mTOR complex 1 (mTORC1), bridges nutrient signaling to metabolic processes necessary for cell growth. Signaling through mTORC1 induces both nucleotide and lipid synthesis. We observed elevated mTORC1 signaling on activation in both NKG2C- and NKG2C+ NK cells from HCMV+ donors relative to those from HCMV- donors, demonstrating a correlation between higher mTORC1 activity and synthesis of key metabolites for cell growth and division.

SARS-CoV-2 seroprevalence among blood donors in Uganda: 2019-2022.

The true burden of COVID-19 in low- and middle-income countries remains poorly characterized, especially in Africa. Even prior to the availability of SARS-CoV-2 vaccines, countries in Africa had lower numbers of reported COVID-19 related hospitalizations and deaths than other regions globally. Ugandan blood donors were evaluated between October 2019 and April 2022 for IgG antibodies to SARS-CoV-2 nucleocapsid (N), spike (S), and five variants of the S protein using multiplexed electrochemiluminescence immunoassays (MesoScale Diagnostics, Rockville, MD). Seropositivity for N and S was assigned using manufacturer-provided cutoffs and trends in seroprevalence were estimated by quarter. Statistically significant associations between N and S antibody seropositivity and donor characteristics in November-December 2021 were assessed by chi-square tests. A total of 5393 blood unit samples from donors were evaluated. N and S seropositivity increased throughout the pandemic to 82.6% in January-April 2022. Among seropositive individuals, N and S antibody levels increased ≥9-fold over the study period. In November-December 2021, seropositivity to N and S antibody was higher among repeat donors (61.3%) compared with new donors (55.1%; p = .043) and among donors from Kampala (capital city of Uganda) compared with rural regions (p = .007). Seropositivity to S antibody was significantly lower among HIV-seropositive individuals (58.8% vs. 84.9%; p = .009). Despite previously reported low numbers of COVID-19 cases and related deaths in Uganda, high SARS-CoV-2 seroprevalence and increasing antibody levels among blood donors indicated that the country experienced high levels of infection over the course of the pandemic.

Chagas disease in the Brazilian Northeast: understanding health and living conditions in a population with a historical transmission risk in the rural area

Chagas disease (CD) is considered a neglected disease by the World Health Organization and requires priority from the health authorities of the American continent. In Brazil, few data are available to evaluate the real situation of endemic areas for CD, mainly in the Northeast region. Thus, the objective of the study was to evaluate the living conditions, clinical aspects and prevalence of infection in inhabitants of rural areas endemic to CD. Blood was collected and submitted to diagnostic ELISA and indirect immunofluorescence techniques. A questionnaire covering sociodemographic information and knowledge related to CD was applied, and general clinical evaluation and swallowing assessment were performed. Twenty-four (7.04%) seropositive individuals were identified, of whom 83.3% were women with most in the age range of 30-60 years old. The majority of the population has a low level of education. Regarding the risk variables for CD, an association was noted between the presence of kissing bugs (OR 9.8) and contact/manipulation (OR 20.2), transfusion (OR 10.6), and sugarcane juice intake (OR 5.1). Was possible to detect changes in swallowing. The present study revealed the existence of a population seropositive for CD without follow-up for their health condition. In addition, some of these patients present changes in swallowing that may be related to the chronic phase. Although no infected children were identified, the area may be considered at risk due to the environmental and socioeconomic conditions of its population and the presence of infected vectors previously found in the area.

Seroprevalence and clinical characteristics of SARS-CoV-2 infection in children with cystic fibrosis.

People with cystic fibrosis (PwCF) have chronic lung disease and may be at increased risk of coronavirus disease 2019 (COVID-19)-related morbidity and mortality. This study aimed to determine seroprevalence and clinical characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children with cystic fibrosis (CF), and to assess antibody responses following SARS-CoV-2 infection or vaccination. Children and adolescents with CF followed at Seattle Children's Hospital were enrolled between July 20, 2020 and February 28, 2021. SARS-CoV-2 serostatus was determined on enrollment at 6 and 11 months (±2 months) for nucleocapsid and spike IgG. Participants completed intake and weekly surveys inquiring about SARS-CoV-2 exposures, viral/respiratory illnesses, and symptoms. Of 125 PwCF enrolled, 14 (11%) had positive SARS-CoV-2 antibodies consistent with recent or past infection. Seropositive participants were more likely to identify as Hispanic (29% vs. 8%, p = 0.04) and have pulmonary exacerbations requiring oral antibiotics in the year prior (71% vs. 41%, p = 0.04). Five seropositive individuals (35.7%) were asymptomatic, while six (42.9%) reported mild symptoms, primarily cough and nasal congestion. Antispike protein IgG levels were approximately 10-fold higher in participants following vaccination compared with participants who had natural infection alone (p < 0.0001) and resembled levels previously reported in the general population. A majority of PwCF have mild or no symptoms of SARS-CoV-2 making it difficult to distinguish from baseline respiratory symptoms. Hispanic PwCF may be disproportionately impacted, consistent with racial and ethnic COVID-19 disparities among the general US population. Vaccination in PwCF generated antibody responses similar to those previously reported in the general population.

WS18.06 The impact of cytomegalovirus on airway epithelial gene expression

Introduction: The pathogenicity of cytomegalovirus (CMV) has predominantly been recognized in immunosuppressed populations & newborns. However, a recent study in persons with CF observed that CMV seropositive individuals died from lung disease 8 years sooner than those who were seronegative. Further, CMV DNA was identified in those individuals’ sputum (Parkins 2019, ERJ). This observation aligns with increasing evidence associating CMV infection with worse outcomes in many inflammatory conditions, and a higher overall mortality. To date, models of CMV infection of human bronchial epithelial (HBE) cells have not been established, limiting our ability to study its impact in CF airways.

Microglia proliferation underlies synaptic dysfunction in the prefrontal cortex: implications for the pathogenesis of HIV-1-associated neurocognitive and affective alterations.

Microglia, which are productively infected by HIV-1, are critical for brain development and maturation, as well as synaptic plasticity. The pathophysiology of HIV-infected microglia and their role in the pathogenesis of HIV-1-associated neurocognitive and affective alterations, however, remains understudied. Three complementary aims were undertaken to critically address this knowledge gap. First, the expression of HIV-1 mRNA in the dorsolateral prefrontal cortex of postmortem HIV-1 seropositive individuals with HAND was investigated. Utilization of immunostaining and/orRNAscope multiplex fluorescent assays revealed prominent HIV-1 mRNA in microglia of postmortem HIV-1 seropositive individuals with HAND. Second, measures of microglia proliferation and neuronal damage were evaluated in chimeric HIV (EcoHIV) rats. Eight weeks after EcoHIV inoculation, enhanced microglial proliferation was observed in the medial prefrontal cortex (mPFC) of EcoHIV rats, evidenced by an increased number of cells co-localized with both Iba1 + and Ki67 + relative to control animals. Neuronal damage in EcoHIV infected rats was evidenced by pronounced decreases in both synaptophysin and postsynaptic density protein 95 (PSD-95), markers of presynaptic and postsynaptic damage, respectively. Third, regression analyses were conducted to evaluate whether microglia proliferation mechanistically underlies neuronal damage in EcoHIV and control animals. Indeed, microglia proliferation accounted for 42-68.6% of the variance in synaptic dysfunction. Collectively, microglia proliferation induced by chronic HIV-1 viral protein exposure may underlie the profound synaptodendritic alterations in HIV-1. Understanding how microglia are involved in the pathogenesis of HAND and HIV-1-associated affective disorders affords a key target for the development of novel therapeutics.

Sexually Transmitted Infections and Risk of Epithelial Ovarian Cancer: Results From the Finnish Maternity Cohort.

Sexually transmitted infections, specifically Chlamydia trachomatis (CT), may be associated with epithelial ovarian cancer (EOC) risk. The association between CT and EOC subtypes is unclear. Our aim was to investigate whether history of CT and other infections (Mycoplasma genitalium [MG], herpes simplex virus type 2 [HSV-2], and human papillomavirus [HPV]) are associated with EOC risk by histotype. We measured antibodies (Abs) to CT, MG, HSV-2, and HPV-16/18 in serum samples in a nested case-control study in the Finnish Maternity Cohort (N = 484 cases 1:1 matched to controls). Logistic regression was used to calculate relative risks (RRs) and 95% confidence intervals (CIs) in seropositive versus seronegative individuals in all cases, as well as serous (n = 249), clear cell and endometrioid (n = 91), and mucinous (n = 144) EOC. CT seropositivity was not associated with EOC risk (eg, CT pGP3-Ab: RR, 0.92 [95% CI, .72-1.19]), regardless of disease subtype. We observed a positive association between MG seropositivity and mucinous EOC (RR, 1.66 [95% CI, 1.09-2.54]; P for heterogeneity by histotype ≤ .001), but not other subtypes. No associations were observed with seropositivity to multiple STIs. CT infection was not associated with EOC risk, with associations observed only for MG and mucinous EOC. Mechanisms linking MG to mucinous EOC remain to be elucidated.

Comparing the performance of dengue virus IgG and IgG-capture enzyme-linked immunosorbent assays in seroprevalence study

BackgroundDengue virus (DENV) is the leading cause of arboviral diseases in humans worldwide. Currently Dengvaxia, the first dengue vaccine licensed in 20 countries, was recommended for DENV seropositive individuals aged 9–45 years. Studying dengue seroprevalence can improve our understanding of the epidemiology and transmission dynamics of DENV, and facilitate future intervention strategies and assessment of vaccine efficacy. Several DENV envelope protein-based serological tests including IgG and IgG-capture enzyme-linked immunosorbent assays (ELISAs) have been employed in seroprevalence studies. Previously DENV IgG-capture ELISA was reported to distinguish primary and secondary DENV infections during early convalescence, however, its performance over time and in seroprevalence study remains understudied.MethodsIn this study, we used well-documented neutralization test- or reverse-transcription-polymerase-chain reaction-confirmed serum/plasma samples including DENV-naïve, primary and secondary DENV, primary West Nile virus, primary Zika virus, and Zika with previous DENV infection panels to compare the performance of three ELISAs.ResultsThe sensitivity of the InBios IgG ELISA was higher than that of InBios IgG-capture and SD IgG-capture ELISAs. The sensitivity of IgG-capture ELISAs was higher for secondary than primary DENV infection panel. Within the secondary DENV infection panel, the sensitivity of InBios IgG-capture ELISA decreased from 77.8% at < 6 months to 41.7% at 1–1.5 years, 28.6% at 2–15 years and 0% at > 20 years (p < 0.001, Cochran-Armitage test for trend), whereas that of IgG ELISA remains 100%. A similar trend was observed for SD IgG-capture ELISA.ConclusionsOur findings demonstrate higher sensitivity of DENV IgG ELISA than IgG-capture ELISA in seroprevalence study and interpretation of DENV IgG-capture ELISA should take sampling time and primary or secondary DENV infection into consideration.

Robust specific RBD responses and neutralizing antibodies after ChAdOx1 nCoV-19 and CoronaVac vaccination in SARS-CoV-2- seropositive individuals.

The pandemic unleashed by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 500 million people worldwide and caused more than 6 million deaths. Cellular and humoral immunity induced by infection or immunization are key factors in controlling the viral burden and avoiding the recurrence of coronavirus disease. The duration and effectiveness of immunity after infection is relevant to pandemic policy interventions, including the timing of vaccine boosters. We sought to evaluate longitudinal binding and functional antibodies against SARS-CoV-2 receptor-binding domain in police officers and health care workers with a history of coronavirus disease 2019 and compare with SARS-CoV-2-naive individuals after vaccination with adenovirus-based ChAdOx1 nCoV-19 (AstraZeneca-Fiocruz) or the inactivated CoronaVac vaccine (Sinovac-Butantan Institute). A total of 208 participants were vaccinated. Of these, 126 (60.57%) received the ChAdOx1 nCoV-19 vaccine and 82 (39.42%) received the CoronaVac vaccine. Prevaccination and postvaccination blood was collected, and the amount of anti-SARS-CoV-2 IgG and the neutralizing ability of the antibodies to block the interaction between angiotensin-converting enzyme 2 and receptor-binding domain were determined. Subjects with preexisting SARS-CoV-2 immunity and who received a single dose of ChAdOx1 nCoV-19 or CoronaVac have similar or superior antibody levels when compared with levels in seronegative individuals even after 2 doses of the vaccine. Neutralizing antibody titers of seropositive individuals were higher with a single dose of either ChAdOx1 nCoV-19 or CoronaVac compared with those of seronegative individuals. After 2 doses, both groups reached a plateau response. Our data reinforce the importance of vaccine boosters to increase specific binding and neutralizing SARS-CoV-2 antibodies.

Single cell transcriptomes from HCMV +donors reveal a unique NKG2C Highsubset that represents true memory NK cells

Abstract Infection with human cytomegalovirus (HCMV) can result in severe morbidity and mortality to the developing fetus and immunocompromised individuals. Natural killer (NK) cells are cytotoxic lymphocytes that are required to manage and control HCMV infections. The NKG2C receptor expressed by NK cells recognizes and responds to infected cells expressing HLA-E loaded with HCMV UL40-derived peptide. These responding NKG2C +NK cells have been referred to as ‘adaptive NK’ because they possess features of adaptive immunity and are found at greater percentages in HCMV seropositive individuals. The molecular mechanisms by which adaptive NK cells are generated and their transcriptomic signatures remain unknown. To investigate this, we obtained healthy adult spleens from four HCMV +and four HCMV −donors and their NK cells were sorted and captured for single-cell RNA-sequencing (scRNA-seq). Donor median age was 59 [IQR 48.5–56.5], 50% (n=4) were female, 50% (n=2) of females were HCMV seropositive and 50% (n=2) of females were HCMV seronegative. Using scRNA-seq, we observed elevated expression and cell numbers of NKG2C in HCMV +donors when compared to HCMV-donors. We identified a distinct population of NKG2C +adaptive NK cells displaying elevated levels of CD52, B3GAT1, FCGR3A, CD3E, and IL7R. In addition, our developmental trajectory analysis of adaptive NKG2C +NK cells revealed a unique branchpoint of true memory NK cells expressing elevated levels of NKG2C and IL7R. Here, we demonstrate that HCMV infection can induce the formation of adaptive NKG2C +NK cells that display a unique transcriptional and developmental profile. These findings have the potential to influence the future application of adaptive NK cells in cellular immunotherapies. This work is supported by the National Center for Advancing Translational Sciences, National Institutes of Health, through grant number TL1TR001437

SARS-CoV-2 infection- induced seroprevalence among children and associated risk factors during the pre- and omicron-dominant wave, from January 2021 through December 2022, Thailand: A longitudinal study.

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection can be asymptomatic in young children. Therefore, the true rate of infection is likely underestimated. Few data are available on the rate of infections in young children, and studies on SARS-CoV-2 seroprevalence among children during the omicron wave are limited. We assessed the SARS-CoV-2 infection-induced seroprevalence among children and estimated the associated risk factors for seropositivity. A longitudinal serological survey was conducted from January 2021 through December 2022. The inclusion criteria were healthy children between 5 and 7 years old and their parents or legal guardians provided written informed consent. Samples were tested for anti-nucleocapsid (N) IgG and anti-receptor binding domain (RBD) IgG using a chemiluminescent microparticle immunoassay (CMIA), and total anti-RBD immunoglobulin (Ig) was detected using an electrochemiluminescence immunoassay (ECLIA). The vaccination and SARS-CoV-2 infection history were collected. In all, 457 serum samples were obtained from 241 annually followed-up children in this longitudinal serological survey. Of these, 201 participants provided samples at two serial time points-during the pre-omicron and omicron-dominant wave. Overall, seroprevalence induced by SARS-CoV-2 infection increased from 9.1% (22/241) during the pre-omicron to 48.8% (98/201) during the omicron wave. Amongst seropositive individuals, the infection-induced seropositivity was lower in vaccinated participants with two doses of BNT162b2 than in the unvaccinated participants (26.4% vs. 56%; OR, 0.28; 95%CI: 0.14-0.58). Nevertheless, the ratio of seropositive cases per recalled infection was 1.63 during the omicron dominant wave. The overall seroprevalence induced by infection, vaccination, and hybrid immunity was 77.1% (155/201) between January and December 2022. We report an increase in infection-induced seroprevalence among children during the omicron wave. These findings highlight that a seroprevalence survey can help determine the true rate of infection, particularly in asymptomatic infection, and optimize public health policies and vaccine strategies in the pediatric population.

Spotted fever group rickettsiae and Anaplasma phagocytophilum in Borrelia burgdorferi sensu lato seropositive individuals with or without Lyme disease: A retrospective analysis

BackgroundThe Ixodes ricinus tick is the main vector of Borrelia burgdorferi and tick-borne encephalitis virus in Switzerland. Spotted fever group Rickettsiae (SFG) and Anaplasma phagocytophilum have been detected in Swiss ticks, however, information about the extent and clinical presentation of these infections in humans is scant. MethodsIndirect fluorescent antibody tests for SFG rickettsiae and Anaplasma phagocytophilum were performed on serum samples of 121 Borrelia burgdorferi seropositive patients with and without Lyme disease and 43 negative controls. ResultsOut of 121 Borrelia burgdorferi seropositive individuals, 65 (53.7%) were seropositive for IgG and 15 (12.4%) for IgM antibodies to SFG rickettsiae. IgM antibodies were detected more frequently in early-than in late-stage of Lyme disease (12 out of 51 and 2 out of 49; respectively; p ​= ​0.0078). Significantly higher IgG antibody titers against SFG rickettsiae were found in patients with late-stage compared to patients with early-stage Lyme disease (mean titer 1:261 and 1:129, respectively; p ​= ​0.038). This difference was even more pronounced in patients with acrodermatitis chronica atrophicans compared to patients with early stage of Lyme disease (mean titer 1:337 and 1:129, respectively; p ​= ​0.009).In patients presenting with fatigue, headache and myalgia, the prevalence of IgG antibodies against SFG rickettsiae was significantly higher (7 out of 11; 63.6%) than in Borrelia burgdorferi seropositive individuals without clinical illness (1 out of 10; 10%; p ​= ​0.024). IgG antibodies to Anaplasma phagocytophilum were detected in 12 out of 121 individuals (9.9%), no IgM antibodies were found. ConclusionInfections with SFG rickettsiae and Anaplasma phagocytophilum are underdiagnosed and should be ruled out after a tick bite. Further studies are needed to elucidate the possible causative role of SFG rickettsiae for myalgia, headache and long-lasting fatigue after a tick bite and to determine the necessity for an antibiotic treatment.

Naturally acquired antibody response to Plasmodium falciparum and Plasmodium vivax among indigenous Orang Asli communities in Peninsular Malaysia.

Malaria remains a public health problem in many parts of the world. In Malaysia, the significant progress towards the national elimination programme and effective disease notification on malaria has resulted in zero indigenous human malaria cases since 2018. However, the country still needs to determine the extent of malaria exposure and transmission patterns, particularly in high-risk populations. In this study, a serological method was used to measure transmission levels of Plasmodium falciparum and Plasmodium vivax among indigenous Orang Asli communities in Kelantan, Peninsular Malaysia. A community-based cross-sectional survey was conducted in three Orang Asli communities (i.e., Pos Bihai, Pos Gob, and Pos Kuala Betis) in Kelantan from June to July 2019. Antibody responses to malaria were assessed by enzyme-linked immunosorbent assay (ELISA) using two P. falciparum (PfAMA-1 and PfMSP-119) and two P. vivax (PvAMA-1 and PvMSP-119) antigens. Age-adjusted antibody responses were analysed using a reversible catalytic model to calculate seroconversion rates (SCRs). Multiple logistic regression was used to investigate factors associated with malaria exposure. The overall malaria seroprevalence was 38.8% for PfAMA-1, 36.4% for PfMSP-119, 2.2% for PvAMA-1, and 9.3% for PvMSP-119. Between study areas, the proportion of seropositivity for any P. falciparum and P. vivax antigens was significantly highest in Pos Kuala Betis with 34.7% (p < 0.001) and 13.6% (p < 0.001), respectively. For all parasite antigens except for PvAMA-1, the proportion of seropositive individuals significantly increased with age (all p < 0.001). Based on the SCR, there was a higher level of P. falciparum transmission than P. vivax in the study area. Multivariate regression analyses showed that living in Pos Kuala Betis was associated with both P. falciparum (adjusted odds ratio [aOR] 5.6, p < 0.001) and P. vivax (aOR 2.1, p < 0.001) seropositivities. Significant associations were also found between age and seropositivity to P. falciparum and P. vivax antigens. Analysis of community-based serological data helps describe the level of transmission, heterogeneity, and factors associated with malaria exposure among indigenous communities in Peninsular Malaysia. This approach could be an important adjunct tool for malaria monitoring and surveillance in low malaria transmission settings in the country.

Detection of humoral and cellular immune response to anti-SARS-CoV-2 BNT162b2 vaccine in breastfeeding women and naïve and previously infected individuals

This study explored humoral and cellular responses to anti-SARS-CoV-2 BNT162b2 mRNA vaccine in breastfeeding women and naïve and seropositive individuals in the first six months after vaccination.Sixty-one volunteers vaccinated with two doses of the BNT162b2 mRNA vaccine were enrolled in the study. In-house developed ELISA was used for the quantification of SARS-CoV-2 RBD-specific antibodies. Cell surface marker expression and intracellular IFN-γ analysis were carried out by flow cytometry. The concentrations of IFN-γ, IL-6 and TNF were determined by ELISA. A significant rise in anti-RBD IgG antibody levels was observed 14 days after the first vaccine dose (p < 0.0001) in serum and milk. The expression of CD28 on CD4+ T cells was significantly higher compared to baseline (p < 0.05). There was a significant increase (p ≤ 0.05) in B cell lymphocyte subset after revaccination, and increased percentage of CD80+ B cells. The expression of IFN-γ in peripheral blood lymphocytes, CD3+ T cells and serum was significantly increased (p < 0.05). No significant difference in immune response was observed between breastfeeding women and other study participants. The anti-SARS-CoV-2 BNT162b2 mRNA vaccine-induced measurable and durable immune response in breastfeeding women and in naïve and previously infected individuals.