European seroepidemiology network 2: Standardisation of assays for seroepidemiology of varicella zoster virus.
BACKGROUND
The aim of the European Sero-Epidemiology Network (ESEN2) is to harmonise the serological surveillance of vaccine-preventable diseases in Europe.


OBJECTIVE
To allow comparison of antibody prevalence in different countries by standardising results into common units.


METHODS
For varicella zoster virus (VZV), a reference laboratory established a panel of 148 samples, characterised by indirect enzyme-immunoassay (ELISA), indirect immunofluorescence, and complement fixation test. Fifty-seven samples were also studied by the fluorescence antibody to membrane antigen test. The geometric mean of the antibody activity (GMAA) obtained from four ELISA determinations was used to characterise each sample of the panel as positive (GMAA: >100 mIU/ml), equivocal (GMAA: 50-100 mIU/ml) or negative (GMAA: <50 mIU/ml) for antibody to VZV (anti-VZV). Thirteen laboratories, using five different ELISA tests, tested the panel.


RESULTS
Agreement with the reference laboratory was above 85% in all cases, and the R(2) values obtained from regression analysis of the quantitative results were always higher than 0.87. Finally, the regression equations could be used to convert national values into a common unitage.


CONCLUSIONS
This study confirmed that results for anti-VZV obtained by different ELISA methods can be converted into common units, enabling the comparison of the seroprevalence profiles obtained in the participant countries.
de Ory
Fernando
F
Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain. fory@isciii.es
Echevarría
José Manuel
JM
Kafatos
George
G
Anastassopoulou
Cleo
C
Andrews
Nick
N
Backhouse
Josephine
J
Berbers
Guy
G
Bruckova
Blazena
B
Cohen
Daniel I
DI
de Melker
Hester
H
Davidkin
Irja
I
Gabutti
Giovanni
G
Hesketh
Louise M
LM
Johansen
Kari
K
Jokinen
Sari
S
Jones
Lindsay
L
Linde
Anika
A
Miller
Elisabeth
E
Mossong
Joël
J
Nardone
Anthony
A
Rota
Maria Cristina
MC
Sauerbrei
Andreas
A
Schneider
François
F
Smetana
Zahava
Z
Tischer
Annedore
A
Tsakris
Athanassios
A
Vranckx
Robert
R
D000914:Antibodies, Viral / Q000032:analysis*; D000956:Antigens, Viral / Q000276:immunology; D005060:Europe; D006562:Herpes Zoster / Q000097:blood*; D014645:Herpesvirus 3, Human / Q000276:immunology*; D006801:Humans; D007753:Laboratories / Q000592:standards; D012015:Reference Standards; D016036:Seroepidemiologic Studies; D012698:Serologic Tests / Q000592:standards*
D000914:Antibodies, Viral; D000956:Antigens, Viral