[Performance of the IgG avidity test in patients with cytomegalovirus disease].
BACKGROUND
IgG antibodies produced early in infection has a low avidity to their respective epitopes, so that an assay to detect those antibodies could be easily used to diagnose a recent primary infection. A prospective study of anti-CMV IgG avidity test in patients with microbiological evidence of active CMV infection was made.


METHODS
One hundred thirty-five patients were studied. All patients sera were tested for CMV antibodies "pool" IgG/IgM, IgM and antibody IgG avidity index (AI). Furthermore, samples of blood leucocytes from immunosuppressed patients to detect CMV viremia by conventional and shell-vial cell culture isolation and to detect CMV antigenemia, were processed. The avidity index IgG-CMV (AI IgG-CMV) less than 60% was defined as a positive result. CMV infection and disease were defined.


RESULTS
The avidity index was < 60% in 16.3% of all patients and in 68.7% of patients with CMV disease. AI IgG-CMV was positive in 81.8% of patients with primary CMV disease and 9.1% with secondary CMV disease. The mean avidity index reading was 35% in primary CMV disease, 88.3% in secondary CMV disease (p < 0.001) and 87.9% in infected patients without CMV disease criterion (p < 0.001). The sensitivity, specificity, VPP and VPN of avidity index IgG-CMV were 85.7%, 97.4%, 75.0% and 94.9% respectively, in primary CMV disease diagnostic respect to all patients with microbiological evidence of active CMV infection.


CONCLUSIONS
Avidity index IgG-CMV seems to be a good serological test to diagnose primary CMV disease with only one serum, probably with independence of patients immune state.
Lafarga
B
B
Servicio de Microbiologia, Hospital Nuestra Senora del Pino, Las Palmas de Gran Canaria.
Noguera
F J
FJ
Bolanos
M
M
Pérez
M C
MC
Rodríguez
H
H
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood* / Q000276:immunology; D000915:Antibody Affinity; D000956:Antigens, Viral / Q000097:blood; D016026:Bone Marrow Transplantation; D003586:Cytomegalovirus Infections / Q000150:complications / Q000175:diagnosis* / Q000276:immunology; D015658:HIV Infections / Q000150:complications; D006801:Humans; D016867:Immunocompromised Host; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology; D007231:Infant, Newborn; D016030:Kidney Transplantation; D008180:Lupus Erythematosus, Systemic / Q000150:complications; D011183:Postoperative Complications / Q000175:diagnosis; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014766:Viremia / Q000175:diagnosis* / Q000276:immunology
D000914:Antibodies, Viral; D000956:Antigens, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M