[Detection of low-avidity IgG antibodies in the diagnosis of primary acute infection by hepatitis C virus].
BACKGROUND
Differential diagnosis of the acute primary infection by hepatitis C virus (HCV) from reactivations and reinfections presents specific problems, especially among patients with impaired humoral immunity. the IgG avidity assay might contribute to resolve these problems.


METHODS
A simple modification of a commercial enzyme immunoassay, allowing evaluation of the avidity of IgG antibody to HCV, was developed and evaluated on a part of 37 serum samples from 14 patients with acute primary infection or reinfection by HCV and 12 samples from 12 seropositive patients lacking evidence of acute infection Eight of the former 14 had impaired ability for antibody response.


RESULTS
The method rendered high percentages of reduction of the antibody signal in samples from acute primary infections taken within two months from onset and significantly lower percentages in samples from reinfections or patients without evidence of acute infection (mean value: 90 degrees C Vs 43% and 25%, respectively. The mean duration of the low-avidity IgG antibody was around six months, but showed wide variations depending on the patient.


CONCLUSIONS
Detection of low-avidity IgG antibody to HCV is easy to perform and may help the study of the HCV infection in some patients. Every method should, however, be carefully validated before using with diagnostic purposes.
León
P
P
Servicio de Microbiología Diagnóstica, Instituto de Salud Carlos III, Majadahonda, Madrid.
López
J A
JA
de Ory
F
F
Elola
C
C
Echevarría
J M
JM
D000208:Acute Disease; D000915:Antibody Affinity; D003937:Diagnosis, Differential; D016174:Hepacivirus / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D006526:Hepatitis C / Q000175:diagnosis* / Q000276:immunology; D018937:Hepatitis C Antibodies / Q000097:blood* / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D012367:RNA, Viral / Q000097:blood; D012008:Recurrence; D014766:Viremia / Q000175:diagnosis
D018937:Hepatitis C Antibodies; D007074:Immunoglobulin G; D012367:RNA, Viral
Detección de anticuerpos IgG de baja avidez en el diagnóstico de la infección primaria aguda por virus de la hepatitis C.