Non-invasive determination of CMV serostatus from dried buccal swab samples: assay development, validation and application to 1.2 million samples

BACKGROUND: Buccal swab sampling constitutes an attractive non-invasive alternative to blood drawings for antibody serostatus assays. Here we describe a method to determine the CMV IgG serostatus from dried buccal swab samples. METHODS: Upon solubilisation, CMV IgG is determined by an ELISA assay specifically adapted to cope with low IgG concentrations. The derived CMV titer is normalised against the total protein concentration to adjust for incorrectly or less efficiently sampled buccal swabs. Assay parameters were optimised on a set of 713 samples. RESULTS: Validation with 1,784 samples revealed distinct results for >80% of samples with 98.6% specificity and 99.1% sensitivity. Based on the analysis of 1.2 million samples we derived age and sex stratified CMV prevalence statistics for Germany, Poland, UK, and Chile. To confirm accuracy of the assay in routine operation, the CMV status of 6,518 donors was reassessed by independent laboratories based on conventional blood samples revealing 96.9% specificity and 97.4% sensitivity. CONCLUSIONS: The assay accurately delivers the CMV IgG serostatus from dried buccal swab samples for >80% of the participants. Thereby it provides a non-invasive alternative to plasma-based CMV monitoring for non-diagnostic purposes such as haematopoietic stem cell transplantation donor screening or population studies.