Matti Waris | University of Turku (original) (raw)
Papers by Matti Waris
Emerging Infectious Diseases, Jun 1, 2023
Frontiers in Bioengineering and Biotechnology, Mar 30, 2023
SARS-CoV-2 emerged at the end of 2019, and like other novel pathogens causing severe symptoms, WH... more SARS-CoV-2 emerged at the end of 2019, and like other novel pathogens causing severe symptoms, WHO recommended heightened biosafety measures for laboratories working with the virus. The positive-stranded genomic RNA of coronaviruses has been known to be infectious since the 1970s, and overall, all experiments with the possibility of SARS-CoV-2 propagation are carried out in higher containment level laboratories. However, as SARS-CoV-2 RNA has been routinely handled in BSL-2 laboratories, the question of the true nature of RNA infectiousness has risen along with discussion of appropriate biosafety measures. Here, we studied the ability of native SARS-CoV-2 genomic RNA to produce infectious viruses when transfected into permissive cells and discussed the biosafety control measures related to these assays. In transfection assays large quantities of genomic vRNA of SARS-CoV-2 was required for a successful production of infectious viruses. However, the quantity of vRNA alone was not the only factor, and especially when the transfected RNA was derived from infected cells, even small amounts of genomic vRNA was enough for an infection. Virus replication was found to start rapidly after transfection, and infectious viruses were detected in the cell culture media at 24 h posttransfection. In addition, silica membrane-based kits were shown to be as good as traditional TRI-reagent based methods in extracting high-quality, 30 kb-long genomic vRNA. Taken together, our data indicates that all transfection experiments with samples containing genomic SARS-CoV-2 RNA should be categorized as a propagative work and the work should be conducted only in a higher containment BSL-3 laboratory.
Research Square (Research Square), Nov 22, 2022
The burden of seasonal human coronavirus (HCoV) infections in early childhood and adults has not ... more The burden 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-speci c 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, during a one 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.
Microbiology spectrum, Oct 31, 2021
The supply of testing equipment is vital in controlling the spread of SARS-CoV-2. We compared the... more The supply of testing equipment is vital in controlling the spread of SARS-CoV-2. We compared the diagnostic efficacy and tolerability of molded plastic (FinSwab; Valukumpu, Finland) versus flocked nylon (FLOQSwab; Copan, Italy) nasopharyngeal swabs in a clinical setting. Adults (n = 112) with suspected symptomatic COVID-19 infection underwent nasopharyngeal sampling with FinSwab and FLOQSwab from the same nostril at a drive-in coronavirus testing station. In a subset of 36 patients the samples were collected in a randomized order to evaluate the discomfort associated with sampling. SARS-CoV-2 and 16 other respiratory viruses, as well as human b-actin mRNA were analyzed by using reverse transcriptase PCR (RT-PCR) assays. Among the 112 patients (mean age, 38 [standard deviation (SD), 14] years) b-actin mRNA was found in all samples. There was no difference in the b-actin mRNA cycle threshold (C T) values between FinSwab (mean, 22.3; SD, 3.61) and FLOQSwab (mean, 22.1; SD, 3.50; P = 0.46) swabs. There were 31 virus-positive cases (26 rhinovirus, 4 SARS-CoV-2, and 1 coronavirus-OC43), 24 of which were positive in both swabs; 3 rhinovirus positives were only found in the FinSwab, and similarly 4 rhinovirus positives were only found in the FLOQSwab. Rhinovirus C T values were similar between swab types. Of the 36 patients, 22 (61%) tolerated the sampling with the FinSwab better than with the FLOQSwab (P = 0.065). The molded plastic nasopharyngeal swab (FinSwab) was comparable to the standard flocked swab in terms of efficacy for respiratory virus detection and tolerability of sampling. IMPORTANCE We demonstrate that a molded plastic swab is a valid alternative to conventional brush-like swabs in collection of a nasopharyngeal sample for virus diagnostics.
Influenza and Other Respiratory Viruses, May 3, 2021
Among all children, the burden of influenza is greatest on the youngest ones. The rates of influe... more Among all children, the burden of influenza is greatest on the youngest ones. The rates of influenza-associated deaths and hospitalizations are highest among infants during the first 6 months of life, and substantial numbers of infants in this age group present with severe sepsis-like illnesses. 1-6 However, even in the youngest age groups, most infants with influenza are managed as outpatients. 7-9 Prevention of influenza in infants is challenging because influenza vaccines are not licensed for use in children younger than
Emerging Infectious Diseases
Open Forum Infectious Diseases, 2017
Background. Current susceptibility testing recommendations for β-hemolytic streptococci outline t... more Background. Current susceptibility testing recommendations for β-hemolytic streptococci outline testing for clindamycin resistance, including inducible resistance by a positive D-zone phenotype. However, few studies describe the prevalence of clindamycin resistance among invasive GCS and GGS organisms. This study aims to describe the prevalence of clindamycin resistance among GCS/GGS compared with invasive group A streptococci (GAS) during the same period in a large United States health system. Methods. Streptococcus isolates from blood, tissue, and body fluids (n = 298) recorded from January 1, 2013 to May 1, 2017 were audited using SafetySurveillor® software. Members of the anginosus-group streptococci were excluded. Specimens submitted to the clinical microbiology laboratory were grown in 5% CO 2 on colistin-nalidixic-acid agar, Mueller-Hinton 5% sheep blood agar, and chocolate agar. Cultures positive for β-hemolytic streptococci were identified to the species level via MALDI-TOF MS. Disk diffusion D-zone testing was performed with 0.5 McFarland standards using erythromycin (15 μg) and clindamycin (2 μg) disks 12 mm apart on Mueller-Hinton 5% sheep blood agar plates incubated at 35°C in 5% CO 2 for 20-24 hours. Susceptibilities to penicillin, erythromycin, clindamycin, and vancomycin were recorded per current CLSI breakpoints. Results. A total of n = 212 GCS/GGS isolates were tested, of which n = 61 (28.8%) demonstrated clindamycin resistance; 85.2% were clindamycin resistant via a positive D-zone phenotype compared with 14.8% that were constitutively clindamycin resistant. A total of n = 86 GAS isolates were tested, of which n = 9 (10%) demonstrated clindamycin resistance; 44% reported clindamycin resistance via a positive D-zone phenotype compared with 56% which were constitutively clindamycin resistant. Conclusion. Clindamycin resistance among GCS and GGS was present in 24.5% of the isolates tested compared with 10% for GAS. As a proportion of the total number of isolates tested, inducible resistance was 14.5% more frequent among GCS and GGS than was observed for GAS. This study demonstrates a higher proportional level of clindamycin resistance in GCS/GGC compared with GAS infections detected over the same study period. Disclosures. All authors: No reported disclosures.
Annals of Medicine, 2021
Objective: Cytokine release syndrome is suggested to be the most important mechanism triggering a... more Objective: Cytokine release syndrome is suggested to be the most important mechanism triggering acute respiratory distress syndrome and end organ damage in COVID-19. The severity of disease may be measured by different biomarkers. Methods: We studied markers of inflammation and coagulation as recorded in 29 patients on admission to the hospital in order to identify markers of severe COVID-19 and need of ICU. Results: Patients who were eventually admitted to ICU displayed significantly higher serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and procalcitonin. No statistical differences were found between the groups in median levels of lymphocytes, D-dimer or ferritin. Conclusions: IL-6 and CRP were the strongest predictors of severity in hospitalized patients with COVID-19.
Influenza and Other Respiratory Viruses, 2020
BackgroundEvery year, influenza viruses infect millions of children and cause an enormous burden ... more BackgroundEvery year, influenza viruses infect millions of children and cause an enormous burden of disease. Young children are at the highest risk for influenza‐attributable hospitalizations. Nevertheless, most young children are treated as outpatients, and limited data are available on the burden of influenza in these children.MethodsWe carried out a prospective cohort study and followed 431 infants born in June‐August 2017 for 10 months from September 1, 2017, to June 30, 2018. The parents filled out daily symptom diaries and were instructed to bring their child for clinical examination at our study clinic each time the child had fever or any signs or symptoms of respiratory tract infection. During each visit, we obtained nasopharyngeal swab specimens for determination of the viral etiology of the illness.ResultsA total of 55 episodes of laboratory‐confirmed influenza were diagnosed among the 408 actively participating children, which corresponds to an annual incidence rate of 13...
Clinical and Translational Allergy, 2019
Background Rhinovirus A and C infections are important contributors to asthma induction and exace... more Background Rhinovirus A and C infections are important contributors to asthma induction and exacerbations. No data exist on the interaction of local immune responses in rhinovirus infection. Therefore, we aimed to determine the tonsillar immune responses according to rhinovirus A, B and C infections. Methods We collected tonsillar samples, nasopharyngeal aspirates and peripheral blood from 42 rhinovirus positive tonsillectomy patients. Fifteen respiratory viruses or their types were investigated from nasopharynx and tonsil tissue, and rhinovirus species were typed. The expression of 10 cytokines and 4 transcription factors (IFN-α, IFN-β, IFN-γ, IL-10, IL-13, IL-17, IL-28, IL-29, IL-37, TGF-β, FOXP3, GATA3, RORC2 and Tbet) were studied from tonsil tissue by quantitative PCR. A standard questionnaire of respiratory symptoms and health was filled by the patient or his/her guardian. The patients were divided into three groups by the determination of rhinovirus species. Results Overall, ...
The Journal of Infectious Diseases, 2019
Human bocavirus 1 (HBoV1) can persist in nasopharynx and tonsils. Using HBoV1 serology, reverse-t... more Human bocavirus 1 (HBoV1) can persist in nasopharynx and tonsils. Using HBoV1 serology, reverse-transcription polymerase chain reaction (PCR) for detecting messenger RNA (mRNA) and quantitative PCR for HBoV1 genome load count, we studied to what extent the HBoV1 DNA loads in nasopharynx correlate with acute infection markers. Tonsillar tissue, nasopharyngeal aspirate, and serum were obtained from 188 elective adeno-/tonsillectomy patients. Relatively high loads of HBoV1 DNA were detected in the nasopharynx of 14 (7%) primarily asymptomatic subjects with negative mRNA and/or serodiagnostic results. Quantitative HBoV1 DNA PCR may have lower specificity than HBoV1 mRNA detection for diagnosing symptomatic infection.
Epidemiology and Infection, 2016
SUMMARYChildren encounter repeated respiratory tract infections during their early life. We condu... more SUMMARYChildren encounter repeated respiratory tract infections during their early life. We conducted a prospective clinical and serological follow-up study to estimate the respiratory syncytial virus (RSV) primary infection and reinfection rates in early childhood. Sera were collected from 291 healthy children at the ages of 13, 24 and 36 months and antibody levels against RSV antigens were determined by enzyme immunoassay. The RT–PCR method was also used for identifying the possible presence of RSV in symptomatic patients. At ages 1, 2 and 3 years, 37%, 68% and 86%, respectively, of studied children were seropositive for RSV. In children seropositive at age 1 year, RSV reinfection rate was at least 37%. Only one of reinfected children showed evidence for a third reinfection by age 3 years. Of children who turned RSV seropositive between ages 1 and 2 years, the reinfection rate was 32% during the third year of life. The mean antibody levels at primary infection were very similar in...
Pediatric Allergy and Immunology, 2010
Acute wheezing in children is almost exclusively associated with respiratory viral infections (1)... more Acute wheezing in children is almost exclusively associated with respiratory viral infections (1). Respiratory syncytial virus (RSV) dominates in infants. Otherwise, respiratory picornaviruses, mainly human rhinovirus (HRV) but also enteroviruses, are the most common viral findings. Human bocavirus (HBoV) has also been a common viral agent in this patient group with the prevalence of up to 19% (1, 2). Rhinovirus has gained interest during recent years because it has been recognized as an important risk factor for asthma among young wheezing children (3-7). The susceptibility to this common cold virus appears to be linked to atopy-related factors (6, 8, 9). The link between RSV or other viral infections and atopy has not been fully established (6, 8, 9). The past studies have not detected several recently discovered viruses.
Clinical Microbiology and Infection, 2013
The shedding of human rhinovirus (HRV) after an acute, naturally acquired infection has not been ... more The shedding of human rhinovirus (HRV) after an acute, naturally acquired infection has not been described in detail. We determined the duration of HRV shedding in immunocompetent children and adults, and in patients with primary hypogammaglobulinaemia. Subjects with symptoms of respiratory tract infection, and their household contacts, were screened for HRV by reverse transcription PCR. They were followed by serial, self-collected nasal swab specimens until negative for HRV or infected by another HRV type. We followed 62 HRV infections in 54 subjects. The mean (95% CI) duration of HRV shedding was 11.4 (8.2-14.7) days in children, 10.1 (7.4-12.9) days in adults, and 40.9 (26.4-55.4) days in patients with hypogammaglobulinaemia (p <0.001). The duration of respiratory tract symptoms correlated with the duration of virus shedding (p 0.002). A new infection by another HRV type soon after the first episode was common. We conclude that the shedding times of HRV are relatively short in otherwise healthy individuals. In contrast, prolonged shedding over 28 days is frequent in patients with hypogammaglobulinaemia despite immunoglobulin replacement therapy.
Bone Marrow Transplantation, 2013
Among the immunocompetent, infections with parvovirus B19 (B19V) and human bocavirus (HBoV) 1 ran... more Among the immunocompetent, infections with parvovirus B19 (B19V) and human bocavirus (HBoV) 1 range clinically from asymptomatic to severe, while following allogeneic hematopoietic SCT (HSCT) B19V can cause a persistent severe illness. The epidemiology and clinical impact of HBoV1 and the other emerging parvovirus 4 (PARV4) among immunocompromised patients have not been established. To determine the occurrence and clinical spectrum of B19V, PARV4 and HBoV1 infections, we performed a longitudinal molecular surveillance among 53 allogeneic HSCT recipients for pre-and post-HSCT DNAemias of these parvoviruses. Quantitative real-time PCR showed B19V DNA in sera of 16 (30%) patients, at mean levels of 4.6 Â 10 3 , 9.9 Â 10 7 , 1.1 Â 10 10 and 1.6 Â 10 2 B19V DNA copies/mL pre-HSCT (9/53), and at 1 (6/53), 2 (4/53) and 3 months (1/25) post HSCT, respectively. However, no clinical manifestation correlated with the presence of B19V viremia. All B19V sequences were of genotype 1. None of the sera investigated contained PARV4 or HBoV1 DNAs. Our data demonstrate B19V viremia to be frequent among pediatric allogeneic HSCT recipients, yet without apparent clinical correlates. PARV4 or HBoV1 viremias were not seen in these immunocompromised patients.
Allergy, 2014
Background: The relationships between tonsillar immune responses, and viral infection and allergy... more Background: The relationships between tonsillar immune responses, and viral infection and allergy are incompletely known. Objective: To study intratonsillar/nasopharyngeal virus detections and in vivo expressions of T-cell-and innate immune response-specific cytokines, transcription factors, and type I/II/III interferons in human tonsils.
Emerging Infectious Diseases, Jun 1, 2023
Frontiers in Bioengineering and Biotechnology, Mar 30, 2023
SARS-CoV-2 emerged at the end of 2019, and like other novel pathogens causing severe symptoms, WH... more SARS-CoV-2 emerged at the end of 2019, and like other novel pathogens causing severe symptoms, WHO recommended heightened biosafety measures for laboratories working with the virus. The positive-stranded genomic RNA of coronaviruses has been known to be infectious since the 1970s, and overall, all experiments with the possibility of SARS-CoV-2 propagation are carried out in higher containment level laboratories. However, as SARS-CoV-2 RNA has been routinely handled in BSL-2 laboratories, the question of the true nature of RNA infectiousness has risen along with discussion of appropriate biosafety measures. Here, we studied the ability of native SARS-CoV-2 genomic RNA to produce infectious viruses when transfected into permissive cells and discussed the biosafety control measures related to these assays. In transfection assays large quantities of genomic vRNA of SARS-CoV-2 was required for a successful production of infectious viruses. However, the quantity of vRNA alone was not the only factor, and especially when the transfected RNA was derived from infected cells, even small amounts of genomic vRNA was enough for an infection. Virus replication was found to start rapidly after transfection, and infectious viruses were detected in the cell culture media at 24 h posttransfection. In addition, silica membrane-based kits were shown to be as good as traditional TRI-reagent based methods in extracting high-quality, 30 kb-long genomic vRNA. Taken together, our data indicates that all transfection experiments with samples containing genomic SARS-CoV-2 RNA should be categorized as a propagative work and the work should be conducted only in a higher containment BSL-3 laboratory.
Research Square (Research Square), Nov 22, 2022
The burden of seasonal human coronavirus (HCoV) infections in early childhood and adults has not ... more The burden 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-speci c 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, during a one 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.
Microbiology spectrum, Oct 31, 2021
The supply of testing equipment is vital in controlling the spread of SARS-CoV-2. We compared the... more The supply of testing equipment is vital in controlling the spread of SARS-CoV-2. We compared the diagnostic efficacy and tolerability of molded plastic (FinSwab; Valukumpu, Finland) versus flocked nylon (FLOQSwab; Copan, Italy) nasopharyngeal swabs in a clinical setting. Adults (n = 112) with suspected symptomatic COVID-19 infection underwent nasopharyngeal sampling with FinSwab and FLOQSwab from the same nostril at a drive-in coronavirus testing station. In a subset of 36 patients the samples were collected in a randomized order to evaluate the discomfort associated with sampling. SARS-CoV-2 and 16 other respiratory viruses, as well as human b-actin mRNA were analyzed by using reverse transcriptase PCR (RT-PCR) assays. Among the 112 patients (mean age, 38 [standard deviation (SD), 14] years) b-actin mRNA was found in all samples. There was no difference in the b-actin mRNA cycle threshold (C T) values between FinSwab (mean, 22.3; SD, 3.61) and FLOQSwab (mean, 22.1; SD, 3.50; P = 0.46) swabs. There were 31 virus-positive cases (26 rhinovirus, 4 SARS-CoV-2, and 1 coronavirus-OC43), 24 of which were positive in both swabs; 3 rhinovirus positives were only found in the FinSwab, and similarly 4 rhinovirus positives were only found in the FLOQSwab. Rhinovirus C T values were similar between swab types. Of the 36 patients, 22 (61%) tolerated the sampling with the FinSwab better than with the FLOQSwab (P = 0.065). The molded plastic nasopharyngeal swab (FinSwab) was comparable to the standard flocked swab in terms of efficacy for respiratory virus detection and tolerability of sampling. IMPORTANCE We demonstrate that a molded plastic swab is a valid alternative to conventional brush-like swabs in collection of a nasopharyngeal sample for virus diagnostics.
Influenza and Other Respiratory Viruses, May 3, 2021
Among all children, the burden of influenza is greatest on the youngest ones. The rates of influe... more Among all children, the burden of influenza is greatest on the youngest ones. The rates of influenza-associated deaths and hospitalizations are highest among infants during the first 6 months of life, and substantial numbers of infants in this age group present with severe sepsis-like illnesses. 1-6 However, even in the youngest age groups, most infants with influenza are managed as outpatients. 7-9 Prevention of influenza in infants is challenging because influenza vaccines are not licensed for use in children younger than
Emerging Infectious Diseases
Open Forum Infectious Diseases, 2017
Background. Current susceptibility testing recommendations for β-hemolytic streptococci outline t... more Background. Current susceptibility testing recommendations for β-hemolytic streptococci outline testing for clindamycin resistance, including inducible resistance by a positive D-zone phenotype. However, few studies describe the prevalence of clindamycin resistance among invasive GCS and GGS organisms. This study aims to describe the prevalence of clindamycin resistance among GCS/GGS compared with invasive group A streptococci (GAS) during the same period in a large United States health system. Methods. Streptococcus isolates from blood, tissue, and body fluids (n = 298) recorded from January 1, 2013 to May 1, 2017 were audited using SafetySurveillor® software. Members of the anginosus-group streptococci were excluded. Specimens submitted to the clinical microbiology laboratory were grown in 5% CO 2 on colistin-nalidixic-acid agar, Mueller-Hinton 5% sheep blood agar, and chocolate agar. Cultures positive for β-hemolytic streptococci were identified to the species level via MALDI-TOF MS. Disk diffusion D-zone testing was performed with 0.5 McFarland standards using erythromycin (15 μg) and clindamycin (2 μg) disks 12 mm apart on Mueller-Hinton 5% sheep blood agar plates incubated at 35°C in 5% CO 2 for 20-24 hours. Susceptibilities to penicillin, erythromycin, clindamycin, and vancomycin were recorded per current CLSI breakpoints. Results. A total of n = 212 GCS/GGS isolates were tested, of which n = 61 (28.8%) demonstrated clindamycin resistance; 85.2% were clindamycin resistant via a positive D-zone phenotype compared with 14.8% that were constitutively clindamycin resistant. A total of n = 86 GAS isolates were tested, of which n = 9 (10%) demonstrated clindamycin resistance; 44% reported clindamycin resistance via a positive D-zone phenotype compared with 56% which were constitutively clindamycin resistant. Conclusion. Clindamycin resistance among GCS and GGS was present in 24.5% of the isolates tested compared with 10% for GAS. As a proportion of the total number of isolates tested, inducible resistance was 14.5% more frequent among GCS and GGS than was observed for GAS. This study demonstrates a higher proportional level of clindamycin resistance in GCS/GGC compared with GAS infections detected over the same study period. Disclosures. All authors: No reported disclosures.
Annals of Medicine, 2021
Objective: Cytokine release syndrome is suggested to be the most important mechanism triggering a... more Objective: Cytokine release syndrome is suggested to be the most important mechanism triggering acute respiratory distress syndrome and end organ damage in COVID-19. The severity of disease may be measured by different biomarkers. Methods: We studied markers of inflammation and coagulation as recorded in 29 patients on admission to the hospital in order to identify markers of severe COVID-19 and need of ICU. Results: Patients who were eventually admitted to ICU displayed significantly higher serum levels of interleukin-6 (IL-6), C-reactive protein (CRP), and procalcitonin. No statistical differences were found between the groups in median levels of lymphocytes, D-dimer or ferritin. Conclusions: IL-6 and CRP were the strongest predictors of severity in hospitalized patients with COVID-19.
Influenza and Other Respiratory Viruses, 2020
BackgroundEvery year, influenza viruses infect millions of children and cause an enormous burden ... more BackgroundEvery year, influenza viruses infect millions of children and cause an enormous burden of disease. Young children are at the highest risk for influenza‐attributable hospitalizations. Nevertheless, most young children are treated as outpatients, and limited data are available on the burden of influenza in these children.MethodsWe carried out a prospective cohort study and followed 431 infants born in June‐August 2017 for 10 months from September 1, 2017, to June 30, 2018. The parents filled out daily symptom diaries and were instructed to bring their child for clinical examination at our study clinic each time the child had fever or any signs or symptoms of respiratory tract infection. During each visit, we obtained nasopharyngeal swab specimens for determination of the viral etiology of the illness.ResultsA total of 55 episodes of laboratory‐confirmed influenza were diagnosed among the 408 actively participating children, which corresponds to an annual incidence rate of 13...
Clinical and Translational Allergy, 2019
Background Rhinovirus A and C infections are important contributors to asthma induction and exace... more Background Rhinovirus A and C infections are important contributors to asthma induction and exacerbations. No data exist on the interaction of local immune responses in rhinovirus infection. Therefore, we aimed to determine the tonsillar immune responses according to rhinovirus A, B and C infections. Methods We collected tonsillar samples, nasopharyngeal aspirates and peripheral blood from 42 rhinovirus positive tonsillectomy patients. Fifteen respiratory viruses or their types were investigated from nasopharynx and tonsil tissue, and rhinovirus species were typed. The expression of 10 cytokines and 4 transcription factors (IFN-α, IFN-β, IFN-γ, IL-10, IL-13, IL-17, IL-28, IL-29, IL-37, TGF-β, FOXP3, GATA3, RORC2 and Tbet) were studied from tonsil tissue by quantitative PCR. A standard questionnaire of respiratory symptoms and health was filled by the patient or his/her guardian. The patients were divided into three groups by the determination of rhinovirus species. Results Overall, ...
The Journal of Infectious Diseases, 2019
Human bocavirus 1 (HBoV1) can persist in nasopharynx and tonsils. Using HBoV1 serology, reverse-t... more Human bocavirus 1 (HBoV1) can persist in nasopharynx and tonsils. Using HBoV1 serology, reverse-transcription polymerase chain reaction (PCR) for detecting messenger RNA (mRNA) and quantitative PCR for HBoV1 genome load count, we studied to what extent the HBoV1 DNA loads in nasopharynx correlate with acute infection markers. Tonsillar tissue, nasopharyngeal aspirate, and serum were obtained from 188 elective adeno-/tonsillectomy patients. Relatively high loads of HBoV1 DNA were detected in the nasopharynx of 14 (7%) primarily asymptomatic subjects with negative mRNA and/or serodiagnostic results. Quantitative HBoV1 DNA PCR may have lower specificity than HBoV1 mRNA detection for diagnosing symptomatic infection.
Epidemiology and Infection, 2016
SUMMARYChildren encounter repeated respiratory tract infections during their early life. We condu... more SUMMARYChildren encounter repeated respiratory tract infections during their early life. We conducted a prospective clinical and serological follow-up study to estimate the respiratory syncytial virus (RSV) primary infection and reinfection rates in early childhood. Sera were collected from 291 healthy children at the ages of 13, 24 and 36 months and antibody levels against RSV antigens were determined by enzyme immunoassay. The RT–PCR method was also used for identifying the possible presence of RSV in symptomatic patients. At ages 1, 2 and 3 years, 37%, 68% and 86%, respectively, of studied children were seropositive for RSV. In children seropositive at age 1 year, RSV reinfection rate was at least 37%. Only one of reinfected children showed evidence for a third reinfection by age 3 years. Of children who turned RSV seropositive between ages 1 and 2 years, the reinfection rate was 32% during the third year of life. The mean antibody levels at primary infection were very similar in...
Pediatric Allergy and Immunology, 2010
Acute wheezing in children is almost exclusively associated with respiratory viral infections (1)... more Acute wheezing in children is almost exclusively associated with respiratory viral infections (1). Respiratory syncytial virus (RSV) dominates in infants. Otherwise, respiratory picornaviruses, mainly human rhinovirus (HRV) but also enteroviruses, are the most common viral findings. Human bocavirus (HBoV) has also been a common viral agent in this patient group with the prevalence of up to 19% (1, 2). Rhinovirus has gained interest during recent years because it has been recognized as an important risk factor for asthma among young wheezing children (3-7). The susceptibility to this common cold virus appears to be linked to atopy-related factors (6, 8, 9). The link between RSV or other viral infections and atopy has not been fully established (6, 8, 9). The past studies have not detected several recently discovered viruses.
Clinical Microbiology and Infection, 2013
The shedding of human rhinovirus (HRV) after an acute, naturally acquired infection has not been ... more The shedding of human rhinovirus (HRV) after an acute, naturally acquired infection has not been described in detail. We determined the duration of HRV shedding in immunocompetent children and adults, and in patients with primary hypogammaglobulinaemia. Subjects with symptoms of respiratory tract infection, and their household contacts, were screened for HRV by reverse transcription PCR. They were followed by serial, self-collected nasal swab specimens until negative for HRV or infected by another HRV type. We followed 62 HRV infections in 54 subjects. The mean (95% CI) duration of HRV shedding was 11.4 (8.2-14.7) days in children, 10.1 (7.4-12.9) days in adults, and 40.9 (26.4-55.4) days in patients with hypogammaglobulinaemia (p <0.001). The duration of respiratory tract symptoms correlated with the duration of virus shedding (p 0.002). A new infection by another HRV type soon after the first episode was common. We conclude that the shedding times of HRV are relatively short in otherwise healthy individuals. In contrast, prolonged shedding over 28 days is frequent in patients with hypogammaglobulinaemia despite immunoglobulin replacement therapy.
Bone Marrow Transplantation, 2013
Among the immunocompetent, infections with parvovirus B19 (B19V) and human bocavirus (HBoV) 1 ran... more Among the immunocompetent, infections with parvovirus B19 (B19V) and human bocavirus (HBoV) 1 range clinically from asymptomatic to severe, while following allogeneic hematopoietic SCT (HSCT) B19V can cause a persistent severe illness. The epidemiology and clinical impact of HBoV1 and the other emerging parvovirus 4 (PARV4) among immunocompromised patients have not been established. To determine the occurrence and clinical spectrum of B19V, PARV4 and HBoV1 infections, we performed a longitudinal molecular surveillance among 53 allogeneic HSCT recipients for pre-and post-HSCT DNAemias of these parvoviruses. Quantitative real-time PCR showed B19V DNA in sera of 16 (30%) patients, at mean levels of 4.6 Â 10 3 , 9.9 Â 10 7 , 1.1 Â 10 10 and 1.6 Â 10 2 B19V DNA copies/mL pre-HSCT (9/53), and at 1 (6/53), 2 (4/53) and 3 months (1/25) post HSCT, respectively. However, no clinical manifestation correlated with the presence of B19V viremia. All B19V sequences were of genotype 1. None of the sera investigated contained PARV4 or HBoV1 DNAs. Our data demonstrate B19V viremia to be frequent among pediatric allogeneic HSCT recipients, yet without apparent clinical correlates. PARV4 or HBoV1 viremias were not seen in these immunocompromised patients.
Allergy, 2014
Background: The relationships between tonsillar immune responses, and viral infection and allergy... more Background: The relationships between tonsillar immune responses, and viral infection and allergy are incompletely known. Objective: To study intratonsillar/nasopharyngeal virus detections and in vivo expressions of T-cell-and innate immune response-specific cytokines, transcription factors, and type I/II/III interferons in human tonsils.