Neutralizing antibodies after the third COVID-19 vaccination in healthcare workers with or without breakthrough infection.

BACKGROUND: Vaccinations against the SARS-CoV-2 are still crucial in combating the ongoing pandemic that has caused more than 700 million infections and claimed almost 7 million lives in the past four years. Omicron (B.1.1.529) variants have incurred mutations that challenge the protection against infection and severe disease by the current vaccines, potentially compromising vaccination efforts. METHODS: We analyzed serum samples taken up to 9 months post third dose from 432 healthcare workers. Enzyme-linked immunosorbent assays (ELISA) and microneutralization tests (MNT) were used to assess the prevalence of vaccine-induced neutralizing antibodies against various SARS-CoV-2 Omicron variants. RESULTS: In this serological analysis we show that SARS-CoV-2 vaccine combinations of BNT162b2, mRNA-1273, and ChAdOx1 mount SARS-CoV-2 binding and neutralizing antibodies with similar kinetics, but with differing neutralization capabilities. The most recent Omicron variants, BQ.1.1 and XBB.1.5, show a significant increase in the ability to escape vaccine and infection-induced antibody responses. Breakthrough infections in thrice vaccinated adults were seen in over 50% of the vaccinees, resulting in a stronger antibody response than without infection. CONCLUSIONS: Different three-dose vaccine combinations seem to induce considerable levels of neutralizing antibodies against most SARS-CoV-2 variants. However, the ability of the newer variants BQ1.1 and XBB 1.5 to escape vaccine-induced neutralizing antibody responses underlines the importance of updating vaccines as new variants emerge.

During the COVID-19 pandemic, mass vaccination efforts against SARS-CoV-2 infection have provided effective protection against the virus and helped reduce the severity of symptoms in infected individuals. However, it is not well established whether the existing vaccines can provide the same protection against new and emerging SARS-CoV-2 variants that develop over time as the virus evolves. In this study, we tested combinations of three-dose COVID-19 vaccines given in random order to protect against all SARS-CoV-2 variants in circulation including the newest being Omicron variants. We demonstrate that more than half of the population who received the three-dose vaccine combinations were infected with SARS-CoV-2 Omicron variants after receiving the last vaccine dose. These findings indicate the need to develop new vaccine candidates against emerging SARS-CoV-2 variants.

Coronavirus spike protein-specific antibodies indicate frequent infections and reinfections in infancy and among BNT162b2-vaccinated healthcare workers.

The prevalence of seasonal human coronavirus (HCoV) infections in early childhood and adults has not been well analyzed in longitudinal serological studies. Here we analyzed the changes in HCoV (229E, HKU1, NL63, OC43, MERS, and SARS-CoV-2) spike-specific antibody levels in follow-up serum specimens of 140 children at the age of 1, 2, and 3 years, and of 113 healthcare workers vaccinated for Covid-19 with BNT162b2-vaccine. IgG antibody levels against six recombinant HCoV spike subunit 1 (S1) proteins were measured by enzyme immunoassay. We show that by the age of three years the cumulative seropositivity for seasonal HCoVs increased to 38-81% depending on virus type. BNT162b2 vaccinations increased anti-SARS-CoV-2 S1 antibodies, but no increase in seasonal coronavirus antibodies associated with vaccinations. In healthcare workers (HCWs), during a 1-year follow-up, diagnostic antibody rises were seen in 5, 4 and 14% of the cases against 229E, NL63 and OC43 viruses, respectively, correlating well with the circulating HCoVs. In 6% of the HCWs, a diagnostic antibody rise was seen against S1 of HKU1, however, these rises coincided with anti-OC43 S1 antibody rises. Rabbit and guinea pig immune sera against HCoV S1 proteins indicated immunological cross-reactivity within alpha-CoV (229E and NL63) and beta-CoV (HKU1 and OC43) genera.

Serological Follow-Up Study Indicates High Seasonal Coronavirus Infection and Reinfection Rates in Early Childhood.

Seasonal human coronaviruses (HCoVs) cause respiratory infections, especially in children. Currently, the knowledge on early childhood seasonal coronavirus infections and the duration of antibody levels following the first infections is limited. Here we analyzed serological follow-up samples to estimate the rate of primary infection and reinfection(s) caused by seasonal coronaviruses in early childhood. Serum specimens were collected from 140 children at ages of 13, 24, and 36 months (1, 2, and 3 years), and IgG antibody levels against recombinant HCoV nucleoproteins (N) were measured by enzyme immunoassay (EIA). Altogether, 84% (118/140) of the children were seropositive for at least one seasonal coronavirus N by the age of 3 years. Cumulative seroprevalences for HCoVs 229E, HKU1, NL63, and OC43 increased by age, and they were 45%, 27%, 70%, and 44%, respectively, at the age of 3 years. Increased antibody levels between yearly samples indicated reinfections by 229E, NL63, and OC43 viruses in 20-48% of previously seropositive children by the age of 3 years. Antibody levels declined 54-73% or 31-77% during the year after seropositivity in children initially seropositive at 1 or 2 years of age, respectively, in case there was no reinfection. The correlation of 229E and NL63, and OC43 and HKU1 EIA results, suggested potential cross-reactivity between the N specific antibodies inside the coronavirus genera. The data shows that seasonal coronavirus infections and reinfections are common in early childhood and the antibody levels decline relatively rapidly. IMPORTANCE The rapid spread of COVID-19 requires better knowledge on the rate of coronavirus infections and coronavirus specific antibody responses in different population groups. In this work we analyzed changes in seasonal human coronavirus specific antibodies in young children participating in a prospective 3-year serological follow-up study. We show that based on seropositivity and changes in serum coronavirus antibody levels, coronavirus infections and reinfections are common in early childhood and the antibodies elicited by the infection decline relatively rapidly. These observations provide further information on the characteristics of humoral immune responses of coronavirus infections in children.

Primary Site of Coxsackievirus B Replication in the Small Intestines: No Proof of Peyer's Patches Involvement.

BACKGROUND: Enterovirus (EV) infections are associated with a broad range of diseases. Since the first experimental infection of primates with poliovirus (PV), tonsils and the Peyer's patches (PPs) have been believed to be the primary replication sites of EVs. Our aim was to localize different viral markers in the small intestines (SI) of coxsackievirus B (CVB) orally and intraperitoneally (i.p.) infected mice. METHODS: Transverse sections of SIs of both infected and control male outbred mice were collected at different intervals post-infection (p.i) and analyzed for presence of interferon-alpha (IFN-α) and viral protein VP1 by immunohistochemistry and in situ hybridization (ISH). Fluorescent marker, eGFP, was identified in cryosections of mice infected with eGFP-CVB3. RESULTS: In the infected SIs, we observed enlarged germinating centers (GCs) in the PPs; IFN-α was detected in the PPs and mucosal layer of the SIs. However, VP1, viral RNA and the eGFP were absent in the GCs of PPs at all stages of infection irrespective of the virus strains used. CONCLUSIONS: Virus was present in the epithelial cells but not in GCs of the PPs of the murine SIs. Our results do not support the hypothesis of EV replication in the PP especially in the GCs.

COVID-19 mRNA vaccine induced antibody responses against three SARS-CoV-2 variants.

As SARS-CoV-2 has been circulating for over a year, dozens of vaccine candidates are under development or in clinical use. The BNT162b2 mRNA COVID-19 vaccine induces spike protein-specific neutralizing antibodies associated with protective immunity. The emergence of the B.1.1.7 and B.1.351 variants has raised concerns of reduced vaccine efficacy and increased re-infection rates. Here we show, that after the second dose, the sera of BNT162b2-vaccinated health care workers (n = 180) effectively neutralize the SARS-CoV-2 variant with the D614G substitution and the B.1.1.7 variant, whereas the neutralization of the B.1.351 variant is five-fold reduced. Despite the reduction, 92% of the seronegative vaccinees have a neutralization titre of >20 for the B.1.351 variant indicating some protection. The vaccinees' neutralization titres exceeded those of recovered non-hospitalized COVID-19 patients. Our work provides evidence that the second dose of the BNT162b2 vaccine induces cross-neutralization of at least some of the circulating SARS-CoV-2 variants.

Monoclonal antibody against VP0 recognizes a broad range of human parechoviruses.

Parechoviruses (PeVs) are common viruses that cause mild gastrointestinal or respiratory symptoms to severe central nervous system infections. In infants, parechovirus infection is one of the leading causes of life-threatening viral disease. High-quality antibodies with broad binding specificities are essential to improve accurate parechovirus diagnosis in diagnostic laboratories. Such antibodies have potential in the development of rapid antigen detection assay against PeVs. In the present study, VP4 and VP2 genes from human parechovirus A1 (PeV-A1) were cloned and VP0 fusion protein produced to develop monoclonal antibodies against PeVs. Two pan-parechovirus antibodies, one IgG and one IgM isotype, were isolated. The properties of IgG1/κ monoclonal (designated as Mab-PAR-1) was studied further. Mab-PAR-1 was shown to be functional in western blot against denatured recombinant protein and viral particles. In immunofluorescence assay, the antibody tested positive for nineteen PeV-A1 isolates while showing no cross-reactivity to fourteen entero- and rhinovirus types. In addition, Mab-PAR-1 showed positive reactivity against five other cultivable parechovirus types 2-6. A unique Mab-PAR-1 epitope located in the junction of the three capsid proteins VP0, VP1, and VP3 was identified using a peptide library screen. This study demonstrates that PeV-A1-VP0 protein is functional antigen for developing monoclonal antibody for diagnosis of broad range of parechovirus infections.

A Combination of N and S Antigens With IgA and IgG Measurement Strengthens the Accuracy of SARS-CoV-2 Serodiagnostics.

BACKGROUND: Primary diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is based on detection of virus RNA in nasopharyngeal swab samples. In addition, analysis of humoral immunity against SARS-CoV-2 has an important role in viral diagnostics and seroprevalence estimates. METHODS: We developed and optimized an enzyme immunoassays (EIA) using SARS-CoV-2 nucleoprotein (N), S1 and receptor binding domain (RBD) of the viral spike protein, and N proteins from SARS, Middle East respiratory syndrome (MERS), and 4 low-pathogenic human CoVs. Neutralizing antibody activity was compared with SARS-CoV-2 IgG, IgA, and IgM EIA results. RESULTS: The sensitivity of EIA for detecting immune response in COVID-19 patients (n = 101) was 77% in the acute phase and 100% in the convalescent phase of SARS-CoV-2 infection when N and RBD were used as antigens in IgG and IgA specific EIAs. SARS-CoV-2 infection significantly increased humoral immune responses against the 229E and NL63 N proteins. S1 and RBD-based EIA results had a strong correlation with microneutralization test results. CONCLUSIONS: The data indicate a combination of SARS-CoV-2 S1 or RBD and N proteins and analysis of IgG and IgA immunoglobulin classes in sera provide an excellent basis for specific and sensitive serological diagnostics of COVID-19.

No Association Between Ljungan Virus Seropositivity and the Beta-cell Damaging Process in the Finnish Type 1 Diabetes Prediction and Prevention Study Cohort.

BACKGROUND: Ljungan virus (LV) has not confirmed to associate with any human disease, but a possible connection with type 1 diabetes has been suggested. LV is a rodent-borne picornavirus that induces a diabetes-like condition in rodents. Approximately 30% of adults and 60% of children are seropositive in Finland. The Finnish Type 1 Diabetes Prediction and Prevention study enabled the use of very well characterized sample panels from children seroconverted to positivity for multiple islet autoantibodies during their prospective observation from birth; in addition, samples from age, sex, human leukocyte antigen (HLA), and residence area matched control children. METHODS: We analyzed LV IgG seroprevalence in 102 case children (65 had also developed type 1 diabetes), in addition to nondiabetic control children. LV and human parechovirus (HPeV) immunofluorescence assays were used to analyze LV and HPeV-specific IgG from 102 plasma samples taken at the time of islet autoantibody appearance and from 204 samples from the matched control children. RESULTS: Altogether 46.1% of the case and 50.7% of the control children were positive for LV IgG (odds ratio 0.8; 95% confidence interval, 0.47-1.36; P = 0.416) and 67.6% versus 79.8% were positive for HPeV IgG, respectively (odds ratio 0.49, 0.27-0.9, P = 0.023). CONCLUSIONS: Thus, no risk associations between LV or HPeV-specific IgG and islet autoimmunity were observed. However, a trend for significantly higher prevalence of HPeV antibodies in control children (P = 0.023) suggests a possible protective association of this virus with islet autoimmunity.

Detection of enteroviruses in stools precedes islet autoimmunity by several months: possible evidence for slowly operating mechanisms in virus-induced autoimmunity.

AIMS/HYPOTHESIS: This case-control study was nested in a prospective birth cohort to evaluate whether the presence of enteroviruses in stools was associated with the appearance of islet autoimmunity in the Type 1 Diabetes Prediction and Prevention study in Finland. METHODS: Altogether, 1673 longitudinal stool samples from 129 case children who turned positive for multiple islet autoantibodies and 3108 stool samples from 282 matched control children were screened for the presence of enterovirus RNA using RT-PCR. Viral genotype was detected by sequencing. RESULTS: Case children had more enterovirus infections than control children (0.8 vs 0.6 infections per child). Time-dependent analysis indicated that this excess of infections occurred more than 1 year before the first detection of islet autoantibodies (6.3 vs 2.1 infections per 10 follow-up years). No such difference was seen in infections occurring less than 1 year before islet autoantibody seroconversion or after seroconversion. The most frequent enterovirus types included coxsackievirus A4 (28% of genotyped viruses), coxsackievirus A2 (14%) and coxsackievirus A16 (11%). CONCLUSIONS/INTERPRETATION: The results suggest that enterovirus infections diagnosed by detecting viral RNA in stools are associated with the development of islet autoimmunity with a time lag of several months.

Intertypic recombination of human parechovirus 4 isolated from infants with sepsis-like disease.

BACKGROUND: Human parechoviruses (HPeVs) (family Picornaviridae), are common pathogens in young children. Despite their high prevalence, research on their genetic identity, diversity and evolution have remained scarce. OBJECTIVES: Complete coding regions of three previously reported HPeV-4 isolates from Finnish children with sepsis-like disease were sequenced in order to elucidate the phylogenetic relationships and potential recombination events during the evolution of these isolates. STUDY DESIGN: The isolated viruses were sequenced and aligned with all HPeV complete genome sequences available in GenBank. Phylogenetic trees were constructed and similarity plot and bootscanning methods were used for recombination analysis. RESULTS: The three HPeV-4 isolates had 99.8% nucleotide sequence similarity. The phylogenetic analysis indicated that capsid-encoding sequences of these HPeV-4 isolates were closely related to other HPeV-4 strains (80.7-94.7% nucleotide similarity), whereas their non-structural region genes 2A to 3C clustered together with several HPeV-1 and HPeV-3 strains, in addition to the HPeV-4 strain K251176-02 (isolated 2002 in the Netherlands), but not with other HPeV-4 strains. However, in 3D-encoding sequence the Finnish HPeV-4 isolates did not cluster with the strain HPeV-4/K251176-02, but instead, formed a distinct group together with several HPeV-1 and HPeV-3 strains. Similarity plot and Bootscan analyses further confirmed intertypic recombination events in the evolution of the Finnish HPeV-4 isolates. CONCLUSION: Intertypic recombination event(s) have occurred during the evolution of HPeV-4 isolates from children with sepsis-like disease. However, due to the low number of parechovirus complete genomes available, the precise recombination partners could not be detected. The results suggest frequent intratypic recombination among parechoviruses.

Human Parechovirus 1 Infection Occurs via αVß1 Integrin.

Human parechovirus 1 (HPeV-1) (family Picornaviridae) is a global cause of pediatric respiratory and CNS infections for which there is no treatment. Although biochemical and in vitro studies have suggested that HPeV-1 binds to αVß1, αVß3 and αVß6 integrin receptor(s), the actual cellular receptors required for infectious entry of HPeV-1 remain unknown. In this paper we analyzed the expression profiles of αVß1, αVß3, αVß6 and α5ß1 in susceptible cell lines (A549, HeLa and SW480) to identify which integrin receptors support HPeV-1 internalization and/or replication cycle. We demonstrate by antibody blocking assay, immunofluorescence microscopy and RT-qPCR that HPeV-1 internalizes and replicates in cell lines that express αVß1 integrin but not αVß3 or αVß6 integrins. To further study the role of ß1 integrin, we used a mouse cell line, GE11-KO, which is deficient in ß1 expression, and its derivate GE11-ß1 in which human integrin ß1 subunit is overexpressed. HPeV-1 (Harris strain) and three clinical HPeV-1 isolates did not internalize into GE11-KO whereas GE11-ß1 supported the internalization process. An integrin ß1-activating antibody, TS2/16, enhanced HPeV-1 infectivity, but infection occurred in the absence of visible receptor clustering. HPeV-1 also co-localized with ß1 integrin on the cell surface, and HPeV-1 and ß1 integrin co-endocytosed into the cells. In conclusion, our results demonstrate that in some cell lines the cellular entry of HPeV-1 is primarily mediated by the active form of αVß1 integrin without visible receptor clustering.

Human parechovirus type 3 and 4 associated with severe infections in young children.

BACKGROUND: The symptoms observed in children with human parechovirus (HPeV) infection vary widely from asymptomatic or mild gastrointestinal infections to more severe central nervous system infections and sepsis-like disease. Many of the disease associations are, however, only suggestive. In this study, we examined the connection between HPeV and acute otitis media, lower respiratory infections and suspected central nervous system infections. METHODS: An HPeV specific real-time reverese transcriptase polymerase chain reaction was used to detect HPeV RNA. We analyzed altogether 200 middle-ear fluid samples, 192 nasopharyngeal aspirates, 79 cerebrospinal fluid specimens and 50 serum and 5 fecal or fecal culture samples. Positive samples were typed by sequencing the VP1 region. RESULTS: Seven (8%) of 85 children with suspected central nervous system infections were positive for HPeV. Of these, 4 (all in autumn 2012 and from children <3 months of age) were typed to be HPeV4, whereas 1 child had HPeV3. HPeV4 was detected from stool, serum and cerebrospinal fluid. The children with acute otitis media tested HPeV positive in 2.5% episodes. In the lower respiratory cases, HPeV was absent. CONCLUSIONS: The findings reported in this study suggest that HPeV4 can cause sepsis-like disease in young infants and be present in cerebrospinal fluid. Furthermore, this report shows that HPeV findings in children with more severe symptoms occur also in Finland.

Virus antibody survey in different European populations indicates risk association between coxsackievirus B1 and type 1 diabetes.

Enteroviruses (EVs) have been connected to type 1 diabetes in various studies. The current study evaluates the association between specific EV subtypes and type 1 diabetes by measuring type-specific antibodies against the group B coxsackieviruses (CVBs), which have been linked to diabetes in previous surveys. Altogether, 249 children with newly diagnosed type 1 diabetes and 249 control children matched according to sampling time, sex, age, and country were recruited in Finland, Sweden, England, France, and Greece between 2001 and 2005 (mean age 9 years; 55% male). Antibodies against CVB1 were more frequent among diabetic children than among control children (odds ratio 1.7 [95% CI 1.0-2.9]), whereas other CVB types did not differ between the groups. CVB1-associated risk was not related to HLA genotype, age, or sex. Finnish children had a lower frequency of CVB antibodies than children in other countries. The results support previous studies that suggested an association between CVBs and type 1 diabetes, highlighting the possible role of CVB1 as a diabetogenic virus type.

Immunological changes and increased expression of myxovirus resistance protein a in thyroid tissue of patients with recent onset and untreated Graves' disease.

BACKGROUND: Few studies have systematically examined the immune cells that infiltrate thyroid tissue at the time of the onset of Graves' disease (GD). The role of viruses in the pathogenesis of autoimmune thyroid diseases is controversial. The present study analyzed inflammatory responses with respect to signs of virus infection. METHODS: Thyroid tissue was obtained from 22 patients with newly diagnosed and untreated GD, 24 patients with chronic GD, and 24 controls. Inflammation was assessed by immunostaining for CD4+ and CD8+ T cells, plasma cells (CD138+), and plasmacytoid dendritic cells (PDCs). The production of interferon-inducible myxovirus resistance protein A (MxA) was analyzed as a sign of virus infection. RESULTS: The degree of thyroid inflammation and fibrosis was significantly higher in both patient groups compared with that in controls. The number of CD4+ T cells and plasma cells (activated B cells) was significantly higher in both patient groups. CD8+ cells were only present in patients with chronic disease. MxA expression and the number of PDCs increased only in patients with newly diagnosed GD. There was a strong positive correlation between the number of PDCs and the number of MxA+ leucocytes. CONCLUSION: The increase in CD8+ T cells during the chronic stage of GD suggests that they may play a role in progression of the autoimmune process from early to chronic thyroiditis. Upregulation of MxA expression during the early stages of the disease, and the positive correlation between the number of PDCs and the number of MxA+ leucocytes, suggests that activated PDCs secrete type I IFNs at the lesion site, possibly in response to viral infection.

First two cases of neonatal human parechovirus 4 infection with manifestation of suspected sepsis, Finland.

Human parechoviruses are a family of viruses closely related to enteroviruses, and associated with neonatal sepsis-like syndrome, respiratory symptoms and gastrointestinal infection. Here we present clinical details of two neonatal sepsis cases suspected to be caused by HPeV4 infection. The patients were hospitalized in October, 2012. No other causative agents were detected.

Evidence of Ljungan virus specific antibodies in humans and rodents, Finland.

Ljungan virus (LV, genus Parechovirus, family Picornaviridae) is considered currently to be a rodent-borne virus. Despite suggested human disease associations, its zoonotic potential remains unclear. To date, LV antibody prevalence in both humans and rodents has not been studied. In this study, two different LV immunofluorescence assays (LV IFAs) were developed with LV genotypes 1 (LV strain 87-012G) and 2 (LV strain 145SLG), and cross-neutralization and -reaction studies were carried out with LV strain 145SLG. Finally, a panel of 37 Finnish sera was screened for anti-LV antibodies using two different LV IFAs (LV 145SLG and LV 87-012G) and a neutralization (NT) assay (LV 145SLG), and 50 samples from Myodes glareolus by LV IFA (LV 145SLG). The LV seroprevalence study showed 38% and 18% positivity in humans and M. glareolus, respectively. LV IFAs and NT assays were compared, and the results were in good agreement. The data are the first evidence of humans and rodents coming into contact with LV in Finland. Additional studies are required in order to acquire a better understanding of the prevalence, epidemiological patterns and possible disease association of LV infections.

Is alcoholic pancreatitis associated with enteroviral infection?

AIM: To investigate whether enteroviral infection might trigger acute pancreatitis in patients made susceptible due to high alcohol consumption. METHODS: Patients with alcohol-induced acute pancreatitis were analyzed for signs of simultaneous or preceding enteroviral infection. We studied the serum samples of 40 patients hospitalized for alcohol-induced acute pancreatitis and 40 controls recruited from an alcohol detoxification center. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect enterovirus RNA and diagnose acute viremia. Immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) enteroviral antibodies were measured using enzyme immunoassay to detect subacute and previous infections. The samples were considered positive when the antibody titers were ≥ 15 IU. Furthermore, using RT-PCR, we studied pancreatic biopsy samples obtained during surgery from nine patients with chronic pancreatitis, one patient with acute pancreatitis and ten control patients with pancreatic carcinoma for evidence of persisting enteroviral RNA in the pancreatic tissue. RESULTS: No enterovirus RNA indicating acute viremia was detected by RT-PCR in the serum samples of any patient or control. A high incidence of positive antibody titers was observed in both study groups: IgM antibodies had positive titers in 5/40 (13%) vs 4/40 (10%), P = 0.723; IgG in 15/40 (38%) vs 19/40 (48%), P = 0.366; and IgA in 25/40 (63%) vs 33/40 (83%), P = 0.045, patients and controls, respectively. Ten (25%) patients had severe pancreatitis and two (5%) required treatment in intensive care. The median length of hospitalization was 7 d (range: 3-47 d). The severity of acute pancreatitis or the length of hospitalization was not associated with enteroviral IgM, IgG or IgA antibodies. Five pancreatic biopsy samples tested positive with RT-PCR, three (8%) in the control group and two (5%) in the patient group (P = 0.64). CONCLUSION: The rate of enteroviral infection is not increased in patients with alcohol-induced acute pancreatitis when compared to alcoholics with similar high alcohol use.

Human parechovirus seroprevalence in Finland and the Netherlands.

BACKGROUND: Human parechoviruses (HPeVs) are RNA viruses associated with mild gastrointestinal and respiratory infections in children, but may also cause neonatal sepsis and CNS infections in infants. While the prevalence of HPeVs is known mostly among hospitalized populations, the knowledge of HPeV seroprevalence in the general population is poor. OBJECTIVES: The aim of this study was to identify and compare the HPeV1-6 seroprevalence in Finnish and Dutch populations. STUDY DESIGN: A type specific microneutralization assay was set up for detecting neutralizing antibodies (nABs) against HPeV types 1-6. Altogether 616 serum samples from Finnish and Dutch population were analyzed for antibodies against HPeVs. The samples were collected from Finnish children aged 1, 5 or 10 years, Finnish adults, 0- to 5-year-old Dutch children, Dutch women of childbearing age and Dutch HIV-positive men. RESULTS: In both adult populations, seropositivity was high against HPeV1 (99% in Finnish and 92% in Dutch samples) and HPeV2 (86% and 95%). Against HPeV4, the seropositivity was similar (62% and 60%). In Dutch adults, nABs against HPeV5 and 6 (75% and 74%) were detected more often than in Finnish adults (35% and 57%, respectively). In contrast, seropositivity against HPeV3 was as low as 13% in the Finnish and 10% in the Dutch adults. The seroprevalence of all HPeV types increased with age. CONCLUSIONS: The seroprevalence of HPeVs is high in Finnish and Dutch populations and HPeV type 2 and types 4-6 are significantly more prevalent compared to earlier reports. The seroprevalence of antibodies observed against HPeV3 was low.

Detection of enterovirus in the thyroid tissue of patients with graves' disease.

The etiology and pathogenesis of Graves' disease (GD) are still unknown, although it is thought that both genetic and environmental factors are important. Some indirect evidence implies that a viral infection may be a possible etiologic factor in autoimmunity. The main objective of this study was to examine direct evidence of the presence of enteroviruses (EVs) in the thyroid tissue of patients with GD. Thyroid tissue from 22 patients with newly diagnosed GD was obtained by core needle biopsy, while tissue from 24 patients with chronic GD and 24 control subjects without any autoimmune thyroid diseases was collected during neck surgery. Formalin-fixed, paraffin-embedded thyroid tissue samples were examined for the presence of enterovirus capsid protein using immunohistochemistry and for enterovirus RNA using in situ hybridization. Enterovirus capsid protein was detected in 17 (37%) patients and in 4 (17%) control subjects (P = 0.103). Enterovirus RNA was identified in thyroid tissue from nine (20%) patients, but in none of the control subjects (P = 0.016). Eight (90%) of the nine virus RNA positive patients were also positive for enterovirus protein. This is the first study to analyze thyroid tissue for EVs, including patients with untreated, newly diagnosed GD. The results suggest that EVs are more frequently present in thyroid tissue of patients than controls. Further studies are indicated to explore this association to find out if a low-grade chronic enteroviral infection might be involved in the pathogenesis of GD and if this could offer new therapeutic and preventive opportunities.

Inflammation and increased myxovirus resistance protein A expression in thyroid tissue in the early stages of Hashimoto's thyroiditis.

BACKGROUND: The role of viruses as environmental triggers for Hashimoto's thyroiditis (HT) is controversial. Thyroid epithelial cells express a variety of molecules involved in antiviral responses. This study combined histological, immunological, and virological tests to describe changes in tissue from patients with newly diagnosed and untreated HT. To study the early events, patients with positive thyroid peroxidase antibodies (TPO-Ab) and normal thyroid function were also included. This stage was defined as "prethyroiditis." METHODS: Thyroid tissue was collected from 47 patients with high titers of TPO-Ab and from 24 controls. Seventeen patients had prethyroiditis, 17 had subclinical hypothyroidism, and 13 had overt hypothyroidism. The interferon (IFN)-α/ß-inducible myxovirus resistance protein 1 (myxovirus resistance protein A; MxA) was used as a surrogate marker for type I IFN expression. Inflammation, expression of MxA, and the presence of the enteroviralcapsid protein (VP1) were characterized by immunohistochemistry. The presence of enterovirus (EV) RNA was examined by in situ hybridization. RESULTS: The density of CD4+ T cells was increased in all three patient groups, while CD8+ T cells were increased only in patients with overt hypothyroidism. The density of plasma cells increased as the disease progressed. The density of plasmacytoid dendritic cells and the expression of MxA were significantly increased in all patient groups compared with controls (p<0.01). EV RNA was present in 11% of HT patients, but in none of the control subjects, whereas the enteroviral protein was detected in 19% and 16%, respectively. CONCLUSION: The inflammatory reaction in the thyroid gland is a very early event in the pathogenesis of HT. The increased expression of MxA in the inflamed tissue suggests that type I IFN plays a role in disease development. Whether this is virus-dependent needs to be explored in further studies.