VZV Foundation - A Decade Of Leadership In The Fight Against VZV Infections

	Oral Presentation Abstracts: 60 [60] DEVELOPMENT OF AN ENZYME LINKED IMMUNOSORBENT ASSAY FOR THE DETECTION OF IgG ANTIBODIES TO VARICELLA ZOSTER VIRUS IN ORAL FLUID SAMPLES * Y.S. Talukder (1), R. Gopal (2), J. Breuer (1) and D.W.G. Brown (2) (1) Department of Medical Microbiology, St Bartholomew's and the Royal London Hospital Medical & Dental School, Queen Mary College, London, United Kingdom; (2) Enteric, Respiratory and Neurological Virus Laboratory, Central Public Health Laboratory, London, United Kingdom. The purpose of the study was to develop an assay to detect IgG antibody to varicella zoster virus (VZV) in oral fluid samples. Samples were obtained by rubbing sponge swabs at the base of the teeth and eluting the fluid into phosphate buffered saline containing 10% foetal calf serum and Tween. Three hundred and thirty seven samples were obtained from children aged 1-5 years and 205 samples from adults aged 20-50 years. IgG antibody in the samples was detected in an indirect ELISA based on VZV infected cell antigens and with uninfected cell antigen as a control. Samples were incubated with antigen; bound IgG was detected by anti-IgG enzyme conjugate followed by a chromogenic substrate. The difference in absorbance between antigen and control coated wells was used as a measure of VZV specific antibody. The cut off was found to be 0.1 absorbance units; a value less than 0.1 was taken as a negative result and a value greater or equal to 0.1 was regarded as positive. The performance of the assay was defined using the mixture model to assess the distribution of results. Antibody was detected in 11% individuals at age 1 year, 34% at 2 yrs, increasing to 51% at 4 and 75% at age 5. By age 20 yrs the antibody prevalence rose to 91% and by age 50 yrs to 95%. The results agree with seroprevalence data from other authors and reflect that varicella is predominantly a childhood disease in the UK. We conclude that this indirect assay described here can be used to assess immunity to VZV in the population using oral fluid. Further work is underway to define the sensitivity and specificity of the assay by testing matched serum and saliva samples in the preschool age group and using the serum result as a gold standard. Corresponding Author: Dr DWG Brown, Enteric, Respiratory and Neurological Virus Laboratory, Central Public Health Laboratory, 61 Colindale Avenue, London NW9 5HT, United Kingdom

Oral Presentation Abstracts: 60

[60]

DEVELOPMENT OF AN ENZYME LINKED IMMUNOSORBENT ASSAY FOR THE DETECTION OF IgG ANTIBODIES TO VARICELLA ZOSTER VIRUS IN ORAL FLUID SAMPLES

* Y.S. Talukder (1), R. Gopal (2), J. Breuer (1) and D.W.G. Brown (2)
(1) Department of Medical Microbiology, St Bartholomew's and the Royal London Hospital Medical & Dental School, Queen Mary College, London, United Kingdom;
(2) Enteric, Respiratory and Neurological Virus Laboratory, Central Public Health Laboratory, London, United Kingdom.

The purpose of the study was to develop an assay to detect IgG antibody to varicella zoster virus (VZV) in oral fluid samples. Samples were obtained by rubbing sponge swabs at the base of the teeth and eluting the fluid into phosphate buffered saline containing 10% foetal calf serum and Tween. Three hundred and thirty seven samples were obtained from children aged 1-5 years and 205 samples from adults aged 20-50 years. IgG antibody in the samples was detected in an indirect ELISA based on VZV infected cell antigens and with uninfected cell antigen as a control. Samples were incubated with antigen; bound IgG was detected by anti-IgG enzyme conjugate followed by a chromogenic substrate. The difference in absorbance between antigen and control coated wells was used as a measure of VZV specific antibody. The cut off was found to be 0.1 absorbance units; a value less than 0.1 was taken as a negative result and a value greater or equal to 0.1 was regarded as positive. The performance of the assay was defined using the mixture model to assess the distribution of results. Antibody was detected in 11% individuals at age 1 year, 34% at 2 yrs, increasing to 51% at 4 and 75% at age 5. By age 20 yrs the antibody prevalence rose to 91% and by age 50 yrs to 95%. The results agree with seroprevalence data from other authors and reflect that varicella is predominantly a childhood disease in the UK. We conclude that this indirect assay described here can be used to assess immunity to VZV in the population using oral fluid. Further work is underway to define the sensitivity and specificity of the assay by testing matched serum and saliva samples in the preschool age group and using the serum result as a gold standard.

Corresponding Author: Dr DWG Brown, Enteric, Respiratory and Neurological Virus Laboratory, Central Public Health Laboratory, 61 Colindale Avenue, London NW9 5HT, United Kingdom