Browsing by Subject "serology"

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  • Rusanen, Juuso; Kareinen, Lauri; Levanov, Lev; Mero, Sointu Maarit; Pakkanen, Sari Hannele; Kantele, Anu; Amanat, Fatima; Krammer, Florian; Hedman, Klaus; Vapalahti, Olli; Hepojoki, Jussi (2021)
    Accurate and rapid diagnostic tools are needed for management of the ongoing coronavirus disease 2019 (COVID-19) pandemic. Antibody tests enable detection of individuals past the initial phase of infection and help examine vaccine responses. The major targets of human antibody response in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are the spike glycoprotein (SP) and nucleocapsid protein (NP). We have developed a rapid homogenous approach for antibody detection termed LFRET (protein L-based time-resolved Forster resonance energy transfer immunoassay). In LFRET, fluorophore-labeled protein L and antigen are brought to close proximity by antigen-specific patient immunoglobulins of any isotype, resulting in TR-FRET signal. We set up LFRET assays for antibodies against SP and NP and evaluated their diagnostic performance using a panel of 77 serum/plasma samples from 44 individuals with COVID-19 and 52 negative controls. Moreover, using a previously described SP and a novel NP construct, we set up enzyme linked immunosorbent assays (ELISAs) for antibodies against SARS-CoV-2 SP and NP. We then compared the LFRET assays with these ELISAs and with a SARS-CoV-2 microneutralization test (MNT). We found the LFRET assays to parallel ELISAs in sensitivity (90-95% vs. 90-100%) and specificity (100% vs. 94-100%). In identifying individuals with or without a detectable neutralizing antibody response, LFRET outperformed ELISA in specificity (91-96% vs. 82-87%), while demonstrating an equal sensitivity (98%). In conclusion, this study demonstrates the applicability of LFRET, a 10-min "mix and read" assay, to detection of SARS-CoV-2 antibodies.
  • Jalkanen, Pinja; Pasternack, Arja; Maljanen, Sari; Melen, Krister; Kolehmainen, Pekka; Huttunen, Moona; Lundberg, Rickard; Tripathi, Lav; Khan, Hira; Ritvos, Mikael A.; Naves, Rauno; Haveri, Anu; Österlund, Pamela; Kuivanen, Suvi; Jääskeläinen, Anne J.; Kurkela, Satu; Lappalainen, Maija; Rantasärkkä, Kaisa; Vuorinen, Tytti; Hytönen, Jukka; Waris, Matti; Tauriainen, Sisko; Ritvos, Olli; Kakkola, Laura; Julkunen, Ilkka (2021)
    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), Si 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. Si and RBD-based EIA results had a strong correlation with microneutralization test results. Conclusions. The data indicate a combination of SARS-CoV-2 Si 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.
  • Vaisanen, Elina; Paloniemi, Minna; Kuisma, Inka; Lithovius, Väinö; Kumar, Arun; Franssila, Rauli; Ahmed, Kamruddin; Delwart, Eric; Vesikari, Timo; Hedman, Klaus; Soderlund-Venermo, Maria (2016)
    Two human parvoviruses were recently discovered by metagenomics in Africa, bufavirus (BuV) in 2012 and tusavirus (TuV) in 2014. These viruses have been studied exclusively by PCR in stool and detected only in patients with diarrhoea, although at low prevalence. Three genotypes of BuV have been identified. We detected, by in-house EIA, BuV1-3 IgG antibodies in 7/228 children (3.1%) and 10/180 adults (5.6%), whereas TuV IgG was found in one child (0.4%). All children and 91% of the adults were Finnish, yet interestingly 3/6 adults of Indian origin were BuV-IgG positive. By competition EIA, no cross-reactivity between the BuVs was detected, indicating that the BuV genotypes represent distinct serotypes. Furthermore, we analysed by BuV qPCR stool and nasal swab samples from 955 children with gastroenteritis, respiratory illness, or both, and found BuV DNA in three stools (0.3%) and for the first time in a nasal swab (0.1%). This is the first study documenting the presence of BuV and TuV antibodies in humans. Although the seroprevalences of both viruses were low in Finland, our results indicate that BuV infections might be widespread in Asia. The BuV-specific humoral immune responses appeared to be strong and long-lasting, pointing to systemic infection in humans.
  • Felin, E.; Jukola, E.; Raulo, S.; Fredriksson-Ahomaa, M. (2015)
    The seroprevalence of Salmonella spp., pathogenic Yersinia spp., Toxoplasma gondii and Trichinella spp. was studied in 1353 finishing pigs from 259 farms that were allocated according to farm types: large fattening farms (1000 pig places), small fattening farms (<1000 pig places) and farrow-to-finish farms. The antibodies were analysed with commercial ELISA kits in meat juice samples that were collected at Finnish slaughterhouses. Salmonella antibodies were rare (3% of pigs, 14% of farms) when the cut-off optical density (OD) value 0.2 was used. Antibodies to pathogenic Yersinia spp. and T.gondii were detected in 57% of pigs and 85% of farms (OD 0.3) and in 3% of pigs and 9% of farms (OD 0.15), respectively. No antibodies to Trichinella spp. were detected (OD 0.3). The European Food Safety Authority (EFSA) considers Salmonella spp., Yersinia enterocolitica, T.gondii and Trichinella spp. as the most relevant biological hazards in the context of meat inspection of pigs. The seroprevalence of these important zoonotic pathogens was low in Finland, except that of Yersinia. The seroprevalence of Toxoplasma was significantly higher in pigs originating from small-scale fattening farms (P<0.05). Strong positive correlation was observed at the animal level between Salmonella and Yersinia seropositivity and between Salmonella and Toxoplasma seropositivity (P<0.05). We suggest that these results reflect the level and importance of biosecurity measures applied on the farms. Meat juice serology at slaughter is a useful tool for targeting measures to control these pathogens. The information obtained from analyses should be used as part of the food chain information (FCI).
  • Ivaska, Lotta E.; Christensen, Andreas; Waris, Matti; Puhakka, Tuomo; Vuorinen, Tytti; Allander, Tobias; Söderlund-Venermo, Maria; Jartti, Tuomas (2019)
    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.
  • Ylonen, Venla; Lindfors, Katri; Repo, Marleena; Huhtala, Heini; Fuchs, Valma; Saavalainen, Päivi; Musikka, Alex; Laurila, Kaija; Kaukinen, Katri; Kurppa, Kalle (2020)
    Non-biopsy diagnosis of celiac disease is possible in children with anti-transglutaminase 2 antibodies (TGA) > 10x the upper limit of normal (ULN) and positive anti-endomysial antibodies (EMA). Similar criteria have been suggested for adults, but evidence with different TGA assays is scarce. We compared the performance of four TGA tests in the diagnosis of celiac disease in cohorts with diverse pre-test probabilities. Serum samples from 836 adults with either clinical suspicion or family risk of celiac disease were tested with four commercial TGA assays, EmA and celiac disease-associated genetics. The diagnosis was set based on duodenal lesion or, in some cases, using special methods. 137 (57%) patients with clinical suspicion and 85 (14%) of those with family risk had celiac disease. Positive predictive value (PPV) for 10xULN was 100% in each TGA test. The first non-diagnostic investigations were encountered with ULN 1.0x-5.1x in the clinical cohort and 1.3x-4.9x in the family cohort, respectively. Using the assays' own cut-offs (1xULN) the PPVs ranged 84-100%. Serology-based diagnosis of celiac disease was accurate in adults using different commercial kits and pre-test probabilities using 10xULN. The results also suggest that the ULN threshold for biopsy-omitting approach could be lower.
  • Rantsi, Tiina; Öhman, Hanna; Puolakkainen, Mirja; Bloigu, Aini; Paavonen, Jorma; Surcel, Heljä-Marja; Tiitinen, Aila; Joki-Korpela, Päivi (2018)
    Problem: The accuracy of Chlamydia trachomatis antibody test in predicting tubal factor infertility (TFI) is limited, and more accurate methods are needed. Cell-mediated immune response (CMI) is crucial in the resolution of pathogen, but it may play an important role in the pathogenesis of C trachomatis-associated tubal damage. We studied whether combining the markers of C trachomatis-induced CMI to humoral immune response improves the accuracy of serology in TFI prediction. Method of study: Our prospective study consists of 258 subfertile women, of whom 22 (8.5%) had TFI. Women with other causes for subfertility served as a reference group. Serum C trachomatis major outer membrane protein (MOMP) and chlamydial heat-shock protein 60 (cHSP60) IgG antibodies were measured by ELISA. CMI was studied by lymphocyte proliferation assay in vitro. Results: Serological markers were more prevalent in women with TFI than in other subfertile women (40.9% vs 12.3% for MOMP IgG and 27.3% vs 10.2% for cHSP60 IgG). The best test combination for TFI was C. trachomatis MOMP and cHSP60 antibody with an accuracy of 90.3%, sensitivity of 22.7% and specificity of 96.6%. Positive post-test probability of this combination was 54.2%, and negative post-test probability was 12.4%. Adding of the markers of CMI did not significantly improve the accuracy of serology in TFI prediction. Conclusion: The accuracy of TFI prediction increases when the combination of C trachomatis MOMP and cHSP60 antibody tests is used. C trachomatis-induced CMI was common in our study population, but the markers of CMI did not predict TFI.
  • Ziemele, Inga; Xu, Man; Vilmane, Anda; Rasa-Dzelzkaleja, Santa; Hedman, Klaus; Söderlund-Venermo, Maria; Gardovska, Dace; Nora-Krukld, Zaiga; Murovska, Modra (2019)