Transient and durable T cell reactivity after COVID-19.

This study analyzed whole blood samples (n = 56) retrieved from 30 patients at 1 to 21 (median 9) mo after verified COVID-19 to determine the polarity and duration of antigen-specific T cell reactivity against severe acute respiratory syndrome coronavirus 2-derived antigens. Multimeric peptides spanning the entire nucleocapsid protein triggered strikingly synchronous formation of interleukin (IL)-4, IL-12, IL-13, and IL-17 ex vivo until ∼70 d after confirmed infection, whereafter this reactivity was no longer inducible. In contrast, levels of nucleocapsid-induced IL-2 and interferon-γ remained stable and highly correlated at 3 to 21 mo after infection. Similar cytokine dynamics were observed in unvaccinated, convalescent patients using whole-blood samples stimulated with peptides spanning the N-terminal portion of the spike 1 protein. These results unravel two phases of T cell reactivity following natural COVID-19: an early, synchronous response indicating transient presence of multipolar, antigen-specific T helper (TH) cells followed by an equally synchronous and durable TH1-like reactivity reflecting long-lasting T cell memory.

Impact of ADAR-induced editing of minor viral RNA populations on replication and transmission of SARS-CoV-2.

Adenosine deaminases acting on RNA (ADAR) are RNA-editing enzymes that may restrict viral infection. We have utilized deep sequencing to determine adenosine to guanine (A→G) mutations, signifying ADAR activity, in clinical samples retrieved from 93 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients in the early phase of the COVID-19 pandemic. A→G mutations were detected in 0.035% (median) of RNA residues and were predominantly nonsynonymous. These mutations were rarely detected in the major viral population but were abundant in minor viral populations in which A→G was more prevalent than any other mutation (P < 0.001). The A→G substitutions accumulated in the spike protein gene at positions corresponding to amino acids 505 to 510 in the receptor binding motif and at amino acids 650 to 655. The frequency of A→G mutations in minor viral populations was significantly associated with low viral load (P < 0.001). We additionally analyzed A→G mutations in 288,247 SARS-CoV-2 major (consensus) sequences representing the dominant viral population. The A→G mutations observed in minor viral populations in the initial patient cohort were increasingly detected in European consensus sequences between March and June 2020 (P < 0.001) followed by a decline of these mutations in autumn and early winter (P < 0.001). We propose that ADAR-induced deamination of RNA is a significant source of mutated SARS-CoV-2 and hypothesize that the degree of RNA deamination may determine or reflect viral fitness and infectivity.

Shigella and ETEC have replaced rotavirus as main causes of childhood diarrhea in Rwanda after ten years of rotavirus vaccination.

The causes of diarrhea after ten years of rotavirus vaccination in Rwanda were investigated in 496 children with and 298 without diarrhea using a real-time PCR. Rotavirus was detected in 11% of children with diarrhea (OR 2.48, P=0.002). Comparison of population attributable fractions (PAF) show that Shigella (PAF=11%) and ETEC-eltB (PAF=12%) have replaced rotavirus as the main causative agents. The PAF for rotavirus had declined from 41% pre-vaccination to 6.5%, indicating that rotavirus has become one among several similarly important causes of childhood diarrhea in Rwanda. A rotavirus genotype shift to G3P[8] points at the importance of continued genotype surveillance.

Enrichment Reveals Extensive Integration of Hepatitis B Virus DNA in Hepatitis Delta Virus-Infected Patients.

BACKGROUND: Hepatitis B virus (HBV) DNA may become integrated into the human genome of infected human hepatocytes. Expression of integrations can produce the surface antigen (HBsAg) that is required for synthesis of hepatitis D virus (HDV) particles and the abundant subviral particles in the blood of HBV- and HDV-infected subjects. Knowledge about the extent and variation of HBV integrations and impact on chronic HDV is still limited. METHODS: We investigated 50 pieces of liver explant tissue from 5 patients with hepatitis D-induced cirrhosis, using a deep-sequencing strategy targeting HBV RNA. RESULTS: We found that integrations were abundant and highly expressed, with large variation in the number of integration-derived (HBV/human chimeric) reads, both between and within patients. The median number of unique integrations for each patient correlated with serum levels of HBsAg. However, most of the HBV reads represented a few predominant integrations. CONCLUSIONS: The results suggest that HBV DNA integrates in a large proportion of hepatocytes, and that the HBsAg output from these integrations vary >100-fold depending on clone size and expression rate. A small proportion of the integrations seems to determine the serum levels of HBsAg and HDV RNA in HBV/HDV coinfected patients with liver cirrhosis.

A Capture-Recapture-based Ascertainment Probability Weighting Method for Effect Estimation With Under-ascertained Outcomes.

Outcome under-ascertainment, characterized by the incomplete identification or reporting of cases, poses a substantial challenge in epidemiologic research. While capture-recapture methods can estimate unknown case numbers, their role in estimating exposure effects in observational studies is not well established. This paper presents an ascertainment probability weighting framework that integrates capture-recapture and propensity score weighting. We propose a nonparametric estimator of effects on binary outcomes that combines exposure propensity scores with data from two conditionally independent outcome measurements to simultaneously adjust for confounding and under-ascertainment. Demonstrating its practical application, we apply the method to estimate the relationship between health care work and coronavirus disease 2019 testing in a Swedish region. We find that ascertainment probability weighting greatly influences the estimated association compared to conventional inverse probability weighting, underscoring the importance of accounting for under-ascertainment in studies with limited outcome data coverage. We conclude with practical guidelines for the method's implementation, discussing its strengths, limitations, and suitable scenarios for application.

Hepatitis B virus particles in serum contain minus strand DNA and degraded pregenomic RNA of variable and inverse lengths.

This study utilized digital PCR to quantify HBV RNA and HBV DNA within three regions of the HBV genome. Analysis of 75 serum samples from patients with chronic infection showed that HBV RNA levels were higher in core than in S and X regions (median 7.20 vs. 6.80 and 6.58 log copies/mL; p < .0001), whereas HBV DNA levels showed an inverse gradient (7.71 vs. 7.73 and 7.77 log copies/mL, p < .001). On average 80% of the nucleic acid was DNA by quantification in core. The core DNA/RNA ratio was associated with viral load and genotype. In individual patients, the relations between RNA levels in core, S and X were stable over time (n = 29; p = .006). The results suggest that pregenomic RNA is completely reverse transcribed to minus DNA in ≈75% of the virus particles, whereas the remaining 25% contain both RNA and DNA of lengths that reflect variable progress of the polymerase.

Occult hepatitis B infection in children born to HBeAg-positive women confers a low long-term risk for HBsAg-positive infection.

PURPOSE: Mother-to-child transmission (MTCT) has been the main cause of chronic hepatitis B virus (HBV) infection, particularly in East Asia. Hepatitis B immunoglobulin (HBIG) and vaccination given directly after birth effectively prevents hepatitis B surface antigen (HBsAg)-positive (overt) HBV infection, but occult hepatitis B infection (OBI) may develop despite adequate prophylaxis. The aim of this study was to investigate the long-term outcome in children born to mothers with very high HBV DNA levels with special focus on children discovered in early childhood with OBI. METHODS: One-year and long-term outcome regarding overt and occult HBV infection were analysed in 66 children born to hepatitis B e antigen (HBeAg)-positive mothers, and were compared with one-year outcome in 69 children born to HBeAg-negative mothers. The children were born between 1998 and 2018. RESULTS: Six children born to HBeAg-positive mothers developed overt chronic HBV infection, in two cases after normal pregnancies and despite HBIG and vaccination, but never when nucleotide analogue treatment was given during pregnancy. OBI with HBV DNA detected in serum in the absence of surface antigen (HBsAg) was observed in four children at the age of 1 year. One of them was transiently HBsAg-positive at the age of 7 years. At long-term follow-up, six children had overt chronic infection, one had OBI and six had previous OBI or positive anti-HBc suggesting resolved unidentified infections. CONCLUSION: The results indicate that children born to mothers with high HBV DNA levels have approximately 10% risk to develop OBI despite antiviral treatment, vaccination and HBIG, but that such OBI confers a minimal long-term risk for overt infection, at least in immunocompetent children.

Early unrecognised SARS-CoV-2 introductions shaped the first pandemic wave, Sweden, 2020.

BackgroundDespite the unprecedented measures implemented globally in early 2020 to prevent the spread of SARS-CoV-2, Sweden, as many other countries, experienced a severe first wave during the COVID-19 pandemic.AimWe investigated the introduction and spread of SARS-CoV-2 into Sweden.MethodsWe analysed stored respiratory specimens (n = 1,979), sampled 7 February-2 April 2020, by PCR for SARS-CoV-2 and sequenced PCR-positive specimens. Sequences generated from newly detected cases and stored positive specimens February-June 2020 (n = 954) were combined with sequences (Sweden: n = 730; other countries: n = 129,913) retrieved from other sources for Nextstrain clade assignment and phylogenetic analyses.ResultsTwelve previously unrecognised SARS-CoV-2 cases were identified: the earliest was sampled on 3 March, 1 week before recognised community transmission. We showed an early influx of clades 20A and 20B from Italy (201/328, 61% of cases exposed abroad) and clades 19A and 20C from Austria (61/328, 19%). Clade 20C dominated the first wave (20C: 908/1,684, 54%; 20B: 438/1,684, 26%; 20A: 263/1,684, 16%), and 800 of 1,684 (48%) Swedish sequences formed a country-specific 20C cluster defined by a spike mutation (G24368T). At the regional level, the proportion of clade 20C sequences correlated with an earlier weighted mean date of COVID-19 deaths.ConclusionCommunity transmission in Sweden started when mitigation efforts still focused on preventing influx. This created a transmission advantage for clade 20C, likely introduced from ongoing cryptic spread in Austria. Therefore, pandemic preparedness should have a comprehensive approach, including capacity for large-scale diagnostics to allow early detection of travel-related cases and community transmission.

Induction and subsequent decline of S1-specific T cell reactivity after COVID-19 vaccination.

We analyzed magnitude and duration of SARS-CoV-2-specific T cell responses in healthy, infection-naïve subjects receiving COVID-19 vaccines. Overlapping peptides spanning the N-terminal spike 1 (S1) domain of the spike protein triggered secretion of the T cell-derived cytokine interleukin-2 ex vivo in 94/94 whole blood samples from vaccinated subjects at levels exceeding those recorded in all 45 pre-vaccination samples. S1-specific T cell reactivity was stronger in vaccinated subjects compared with subjects recovering from natural COVID-19 and decayed with an estimated half-life of 134 days in the first six months after the 2nd vaccination. We conclude that COVID-19 vaccination induces robust T cell immunity that subsequently declines. EudraCT 2021-000349-42. https://www.clinicaltrialsregister.eu/ctr-search/search?query=2021-000349-42.

Complex norovirus transmission dynamics at hospital wards revealed by deep sequencing.

Detailed knowledge regarding norovirus transmission within hospitals is limited. We investigated a norovirus hospital outbreak affecting 65 patients at five different wards. PCR showed that 61 (94%) of the patients were infected with genotype II.4 strains. Successful Ion Torrent deep sequencing of GII.4 positive samples from 59 patients followed by phylogenetic analysis revealed that all sequences but two clustered into four distinct clades. Two of the clades belonged to GII.4 Sydney 2012, while the other two belonged to GII.4 New Orleans 2009. One of the clades was predominant at two wards, while two clades were predominant at one ward each. The fourth clade was found in sporadic cases at several wards. Thus, at four out of five wards, variants from one clade were predominant. At one ward, a single clade accounted for all cases, while at three wards the predominant clade accounted for 60%-71% of cases. Analysis of quasispecies variation identified positions that could further discriminate between variants from separate wards. The results illustrate a complex transmission of healthcare-associated norovirus infections and show that sequencing can be used to discriminate between related and unrelated cases.

Rapid Cytokine Release Assays for Analysis of Severe Acute Respiratory Syndrome Coronavirus 2-Specific T Cells in Whole Blood.

BACKGROUND: Waning of immunoglobulin G (IgG) antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) complicates the diagnosis of past infection. The durability of T-cell memory against SARS-CoV-2 remains unclear, and most current T-cell protocols are unsuited for large-scale automation. METHODS: Whole-blood samples from 31 patients with verified past coronavirus disease 2019 (COVID-19) and 46 controls, of whom 40 received COVID-19 vaccine, were stimulated with peptides spanning the nucleocapsid (NC) or spike 1 (S1) regions of SARS-CoV-2 and analyzed for interferon γ in supernatant plasma. Diagnostic accuracy of these assays was evaluated against serum anti-NC and anti-receptor-binding domain S1-IgG. RESULTS: Induction of interferon γ in whole blood by NC or S1 peptides diagnosed past COVID-19 with high accuracy (area under the receiver operating characteristic curve, 0.93 and 0.95, respectively). In accordance with previous studies, NC-IgG levels rapidly waned with only 5 of 17 patients (29%) remaining seropositive >180 days after infection. By contrast, NC peptide-induced T-cell memory responses remained in 13 of 17 study participants (76%) >180 days after infection (P = .01 for comparison with NC-IgG; McNemar test). After 2 vaccine doses, all 18 donors exhibited S1-specific T-cell memory. CONCLUSIONS: Cytokine release assays for the monitoring of T-cell memory in whole blood may be useful for evaluating complications following unverified past COVID-19 and for long-term assessment of vaccine-induced T-cell immunity. CLINICAL TRIALS REGISTRATION: EudraCT 2021-000349-42.

Quantification of Viral RNA in Multiple Pieces of Explant Liver Tissue Shows Distinct Focal Differences in Hepatitis B Infection.

Hepatitis B virus (HBV) DNA and RNA were quantified by digital PCR assays in 20-30 tissue pieces from each of 4 liver explants with cirrhosis caused by HBV. The within-patient variability of HBV RNA levels between pieces was up to a 1000-fold. Core RNA and S RNA levels were similar and correlated strongly when replication was high, supporting that transcription was from covalently closed circular DNA (cccDNA). By contrast, enhanced expression of S RNA relative to cccDNA and core RNA in patients with medium-high or low replication supports that HBV surface antigen (HBsAg) can be expressed mainly from integrated HBV DNA in such patients.

Abundance of Noncircular Intrahepatic Hepatitis B Virus DNA May Reflect Frequent Integration Into Human DNA in Chronically Infected Patients.

BACKGROUND: Hepatitis B virus (HBV) integration has implications for cancer development and surface antigen (HBsAg) production, but methods to quantify integrations are lacking. The aim of this study was to develop a droplet digital PCR (ddPCR) assay discriminating between circular and integrated HBV DNA, and to relate the distribution between the two forms to other HBV markers. METHODS: ddPCR with primers spanning the typical linearization breakpoint in the HBV genome allowed for quantification of the absolute copy numbers of total and circular HBV DNA, and calculation of linear HBV DNA. RESULTS: Analysis of 70 liver biopsies from patients with chronic HBV infection revealed that the fraction of linear HBV DNA, which includes integrations, was higher in HBeAg-negative patients than HBeAg-positive. The ratio between HBsAg and HBV DNA levels in serum correlated with the intrahepatic proportion of linear HBV DNA. Furthermore, ddPCR experiments on serum samples and experiments with nuclease indicated the contribution of encapsidated double-stranded linear DNA and replication intermediates to be limited. CONCLUSIONS: The degree of integration of intrahepatic HBV DNA in the HBeAg-negative stage may be higher than previously anticipated, and integrated DNA may explain the persistence of high HBsAg serum levels in patients with low HBV DNA levels.

Pneumococcal concentration and serotype distribution in preschool children with radiologically confirmed pneumonia compared to healthy controls prior to introduction of pneumococcal vaccination in Zanzibar: an observational study.

BACKGROUND: The World Health Organization recommends pneumococcal vaccination (PCV) in the first year of life. We investigated pneumococcal serotypes in children with clinical or radiologically confirmed pneumonia and healthy controls prior to PCV13 vaccine introduction in Zanzibar. METHODS: Children (n = 677) with non-severe acute febrile illness aged 2-59 months presenting to a health centre in Zanzibar, Tanzania April-July 2011 were included. Nasopharyngeal swabs collected at enrolment were analysed by real-time PCR to detect and quantify pneumococcal serotypes in patients (n = 648) and in healthy asymptomatic community controls (n = 161). Children with clinical signs of pneumonia according to the Integrated Management of Childhood illness guidelines ("IMCI pneumonia") were subjected to a chest-X-ray. Consolidation on chest X-ray was considered "radiological pneumonia". RESULTS: Pneumococcal DNA was detected in the nasopharynx of 562/809 (69%) children (70% in patients and 64% in healthy controls), with no significant difference in proportions between patients with or without presence of fever, malnutrition, IMCI pneumonia or radiological pneumonia. The mean pneumococcal concentration was similar in children with and without radiological pneumonia (Ct value 26.3 versus 27.0, respectively, p = 0.3115). At least one serotype could be determined in 423 (75%) participants positive for pneumococci of which 33% had multiple serotypes detected. A total of 23 different serotypes were identified. One serotype (19F) was more common in children with fever (86/648, 13%) than in healthy controls (12/161, 7%), (p = 0.043). Logistic regression adjusting for age and gender showed that serotype 9A/V [aOR = 10.9 (CI 2.0-60.0, p = 0.006)] and 14 [aOR = 3.9 (CI 1.4-11.0, p = 0.012)] were associated with radiological pneumonia. The serotypes included in the PCV13 vaccine were found in 376 (89%) of the 423 serotype positive participants. CONCLUSION: The PCV13 vaccine introduced in 2012 targets a great majority of the identified serotypes. Infections with multiple serotypes are common. PCR-determined concentrations of pneumococci in nasopharynx were not associated with radiologically confirmed pneumonia. Trial registration Clinicaltrials.gov (NCT01094431).

Upper Respiratory Tract Levels of Severe Acute Respiratory Syndrome Coronavirus 2 RNA and Duration of Viral RNA Shedding Do Not Differ Between Patients With Mild and Severe/Critical Coronavirus Disease 2019.

This study reports longitudinal viral RNA loads from the nasopharynx/throat in patients with mild and severe/critical coronavirus disease 2019 (COVID-19). We also investigated whether the duration of symptoms correlated with the duration of viral RNA shedding. A total of 56 patients were included. The highest viral loads occurred early after onset of symptoms. Neither the viral RNA loads in the upper respiratory tract nor the time to viral RNA clearance differed between patients with mild or severe/critical disease. There was a moderate correlation between number of days with symptoms and number of days with viral RNA shedding in patients with mild COVID-19.

Clinical outcomes in cancer patients with COVID-19 in Sweden.

BACKGROUND: The results of studies on the relationship between cancer and COVID-19 have been conflicting and therefore further studies are needed. We aimed to examine the incidence of COVID-19 among patients at one of the largest oncology departments in Sweden, and to evaluate and identify risk factors for poor outcomes, hospital care and death, associated with COVID-19 among cancer patients. MATERIAL AND METHODS: This retrospective study included cancer patients at a single center who tested positive for SARS-CoV-2 by PCR either in hospital, primary health care center or commercial laboratory between 1 March and 14 August 2020. Clinical and demographic data were collected from the medical records. Logistic regression analysis was used to identify variables that associated the primary outcomes of need for hospital care and death within 30 days of positive test. RESULTS: Of 10,774 patients from the Department of Oncology at Sahlgrenska University Hospital, 135 tested positive for SARS-CoV-2 (1.3%). Twenty-eight patients were excluded from further the data collection since they did not meet the inclusion criteria. Altogether, 107 cancer patients were included and the case fatality rate (CFR) was 12% (13) within 30 days of confirmed SARS-CoV-2 infection by PCR. Increasing years of age (OR 1.10; CI 95% 1.03-1.18), palliative treatment intent (OR 15.7; CI 95% 1.8-135.8), and transition to end-of-life care (OR 52.0; CI 95% 3.7-735.6) were associated with increased odds of death within 30 days. Male sex was associated with needing hospital care (OR 3.7; CI 95% 1.50-9.1). CONCLUSION: As in the general population, male sex was found to be at greater risk of needing hospital care for COVID-19, with terminal cancer disease, and older age increasing the odds of fatality. Compared to the general population, slightly more cancer patients had COVID-19. The CFR was within the lower range of others reported in cancer patients.

High-risk human papillomavirus in patients with oral leukoplakia and oral squamous cell carcinoma-A multi-centre study in Sweden, Brazil and Romania.

OBJECTIVES: Although causal associations between oral leukoplakia (OL), oral squamous cell carcinoma (OSCC) and high-risk human papillomavirus (HR-HPV) have been speculated upon in several reports, conclusive evidence has not been presented. This study investigates whether the number of cases of HR-HPV in OL has increased over time and whether the prevalence of HR-HPV-positive OL differs in various parts of the world. PATIENTS AND METHODS: A total of 432 patients with OL from Sweden, Brazil and Romania were analysed. Patients were divided into historical (1992-2002) and contemporary (2011-2017) cohorts from the respective countries. Seventeen patients with OL developed oral squamous cell carcinoma (OSCC). A real-time PCR assay, targeting HPV sub-types 6,11,16,18,31,33,35,39,45,52,56,58 and 59, was performed to detect HR-HPV in patients with OL. RESULTS: In the Swedish and Romanian cohorts, none of the investigated HPV sub-types were detected. In the Brazilian cohorts, five patients with OL (3%) were positive for HR-HPV, including four patients from the contemporary cohort (HPV 16, 31, 33) and one from the historical cohort (HPV 11). All the cases of OL that transformed into OSCC were HR-HPV-negative, as were the corresponding tumours. CONCLUSIONS: In summary, the prevalence of HR-HPV in OL is low in all the tested countries, and the incidence has not changed over time. HR-HPV in OL does not seem to be a driver of oncogenesis.

Variations among Viruses in Influent Water and Effluent Water at a Wastewater Plant over One Year as Assessed by Quantitative PCR and Metagenomics.

Influent wastewater and effluent wastewater at the Rya treatment plant in Gothenburg, Sweden, were continuously monitored for enteric viruses by quantitative PCR (qPCR) during 1 year. Viruses in effluent wastewater were also identified by next-generation sequencing (NGS) in samples collected during spring, early summer, and winter. Samples of incoming wastewater were collected every second week. Seasonal variations in viral concentrations in incoming wastewater were found for noroviruses GII, sapovirus, rotavirus, parechovirus, and astrovirus. Norovirus GI and GIV and Aichi virus were present in various amounts during most weeks throughout the year, while hepatitis A virus, enterovirus, and adenovirus were identified less frequently. Fluctuations in viral concentrations in incoming wastewater were related to the number of diagnosed patients. The viruses were also detected in treated wastewater, however, with a 3- to 6-log10 reduction in concentration. Seven different hepatitis E virus (HEV) strains were identified in the effluents. Five of these strains belonged to genotype 3 and have been isolated in Sweden from swine, wild boars, and humans and in drinking water. The other two strains were divergent and had not been identified previously. They were similar to strains infecting rats and humans. Surveillance of enteric viruses in wastewater is a tool for early detection and follow-up of gastroenteritis outbreaks in society and for the identification of new viruses that can cause infection in humans.IMPORTANCE Both influent wastewater and treated wastewater at a wastewater treatment plant (WWTP) contain a high variety of human viral pathogens with seasonal variability when followed for 1 year. The peak of the amount of 11 different viruses in the inlet wastewater preceded the peak of the number of diagnosed patients by 2 to 4 weeks. The treatment of wastewater reduced viral concentrations by 3 to 6 log10 Despite the treatment of wastewater, up to 5 log10 virus particles per liter were released from into the surrounding river. Hepatitis E virus (HEV) strains previously identified in drinking water and two new strains, similar to those infecting rats and humans, were identified in the treated wastewater released from the WWTP.

Deep sequencing of liver explant transcriptomes reveals extensive expression from integrated hepatitis B virus DNA.

Hepatitis B virus (HBV) is a major cause of hepatocellular carcinoma (HCC). Integration of HBV DNA into the human genome may contribute to oncogenesis and to the production of the hepatitis B surface antigen (HBsAg). Whether integrations contribute to HBsAg levels in the blood is poorly known. Here, we characterize the HBV RNA profile of HBV integrations in liver tissue in patients with chronic HBV infection, with or without concurrent hepatitis D infection, by transcriptome deep sequencing. Transcriptomes were determined in liver tissue by deep sequencing providing 200 million reads per sample. Integration points were identified using a bioinformatic pipeline. Explanted liver tissue from five patients with end-stage liver disease caused by HBV or HBV/HDV was studied along with publicly available transcriptomes from 21 patients. Almost all HBV RNA profiles were devoid of reads in the core and the 3' redundancy (nt 1830-1927) regions, and contained a large number of chimeric viral/human reads. Hence, HBV transcripts from integrated HBV DNA rather than from covalently closed circular HBV DNA (cccDNA) predominated in late-stage HBV infection, in particular in cases with hepatitis D virus co-infection. The findings support the suggestion that integrated HBV DNA can be a significant source of HBsAg in humans.

Pollen exposure weakens innate defense against respiratory viruses.

BACKGROUND: Hundreds of plant species release their pollen into the air every year during early spring. During that period, pollen allergic as well as non-allergic patients frequently present to doctors with severe respiratory tract infections. Our objective was therefore to assess whether pollen may interfere with antiviral immunity. METHODS: We combined data from real-life human exposure cohorts, a mouse model and human cell culture to test our hypothesis. RESULTS: Pollen significantly diminished interferon-λ and pro-inflammatory chemokine responses of airway epithelia to rhinovirus and viral mimics and decreased nuclear translocation of interferon regulatory factors. In mice infected with respiratory syncytial virus, co-exposure to pollen caused attenuated antiviral gene expression and increased pulmonary viral titers. In non-allergic human volunteers, nasal symptoms were positively correlated with airborne birch pollen abundance, and nasal birch pollen challenge led to downregulation of type I and -III interferons in nasal mucosa. In a large patient cohort, numbers of rhinoviruspositive cases were correlated with airborne birch pollen concentrations. CONCLUSION: The ability of pollen to suppress innate antiviral immunity, independent of allergy, suggests that high-risk population groups should avoid extensive outdoor activities when pollen and respiratory virus seasons coincide.