Plasmonic gold chips for the diagnosis of Toxoplasma gondii, CMV, and rubella infections using saliva with serum detection precision

Sampling the blood compartment by an invasive procedure such as phlebotomy is the most common approach used for diagnostic purposes. However, phlebotomy has several drawbacks including pain, vasovagal reactions, and anxiety. Therefore, alternative approaches should be tested to minimize patient's discomfort. Saliva is a reasonable compartment; when obtained, it generates little or no anxiety. We setup a multiplexed serology assay for detection of Toxoplasma gondii IgG and IgM, rubella IgG, and CMV IgG, in serum, whole blood, and saliva using novel plasmonic gold (pGOLD) chips. pGOLD test results in serum, whole blood, and saliva were compared with commercial kits test results in serum. One hundred twenty serum/saliva sets (Lyon) and 28 serum/whole blood/saliva sets (Nice) from France were tested. In serum and whole blood, sensitivity and specificity of multiplex T. gondii, CMV, and rubella IgG were 100% in pGOLD when compared to commercial test results in serum. In saliva, sensitivity and specificity for T. gondii and rubella IgG were 100%, and for CMV IgG, sensitivity and specificity were 92.9% and 100%, respectively, when compared to commercial test results in serum. We were also able to detect T. gondii IgM in saliva with sensitivity and specificity of 100% and 95.4%, respectively, when compared to serum test results. Serological testing by multiplex pGOLD assay for T. gondii, rubella, and CMV in saliva is reliable and likely to be more acceptable for systematic screening of pregnant women, newborn, and immunocompromised patients.