Diagnostic significance of immunoglobulin G avidity in symptomatic and asymptomatic West Nile virus infection
Rev. Soc. Bras. Med. Trop
;
51(5): 591-595, Sept.-Oct. 2018. tab, graf
Article
in English
| LILACS
| ID: biblio-957467
ABSTRACT
Abstract INTRODUCTION West Nile virus (WNV) immunoglobulin M (IgM) antibodies have been shown to persist for up to 500 days in certain patients. To evaluate the usefulness of immunoglobulin G (IgG) avidity assessment in the diagnosis of WNV infection, we analyzed 54 WNV IgM- and/or IgG-positive serum samples from 39 patients with neuroinvasive disease and 15 asymptomatic cases tested during a seroprevalence investigation. METHODS Serological tests (WNV IgM/IgG antibody detection, IgG avidity) were performed using commercially available enzyme-linked immunosorbent assays. RESULTS WNV IgM antibodies were detected in 47 (87%) samples. Acute/recent WNV infection was confirmed based on low/borderline avidity index (AI) in 44 IgM-positive samples (93.6%). In three IgM-positive samples (6.4%), high IgG AIs were detected, thus indicating persisting IgM antibodies from previous infections. All IgM-negative samples showed high AIs. Patients with WNV neuroinvasive disease tested within 30 days showed low AIs. In six patients tested 34-50 days after disease onset, AI was borderline (42%-60%), suggesting earlier WNV IgG maturation. Samples with the highest IgM values were associated with the lowest AIs (Spearman's rho coefficient -0.767, p < 0.001). CONCLUSIONS Our results indicate that IgG avidity differentiates current/recent WNV infection from persistent IgM seropositivity from the previous WNV transmission season both in patients with WNV neuroinvasive disease and in asymptomatic persons. A strong negative correlation between IgM antibody levels and AI indicates that in cases with very high IgM levels, determination of IgG avidity may not be necessary. As many patients showed rapid avidity maturation, low IgG avidity is indicative of WNV infection within the previous month.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
West Nile Fever
/
West Nile virus
/
Immunoglobulin G
/
Antibodies, Viral
/
Antibody Affinity
Type of study:
Diagnostic study
Limits:
Humans
Language:
English
Journal:
Rev. Soc. Bras. Med. Trop
Journal subject:
Tropical Medicine
Year:
2018
Type:
Article
Affiliation country:
Croatia
/
Italy
Institution/Affiliation country:
Andrija Stampar Teaching Institute of Public Health/HR
/
Clinical Hospital Centre Osijek/HR
/
County Hospital Cakovec/HR
/
Croatian Institute of Public Health/HR
/
Croatian Veterinary Institute/HR
/
General Hospital "Dr Josip Bencevic"/HR
/
General Hospital Varazdin/HR
/
Istituto Zooprofilattico Sperimentale "G. Caporale"/IT
/
Regional Institute Split/HR
/
University of Zagreb/HR
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