The effect of thimerosal-containing and thimerosal-free pediatric flu vaccine on gene expression in Saccharomyces cerevisiae

The effect of thimerosal-containing and thimerosal-free pediatric flu vaccine on gene expression in Saccharomyces cerevisiae

Mercury-based preservatives including thimerosal, typically added to some vaccines, may pose health concerns as mercury toxicity has been implicated in many human diseases. In this study, microarray technology and reverse transcriptase-polymerase chain reaction (RT-PCR) were used to examine the potential effects of a typical dose of thimerosal-containing vaccine (TCV) or thimerosal-free (TFV) pediatric flu vaccine on gene expression in Saccharomyces cerevisiae, a model organism that shares roughly 30% of its genome with humans. Yeast were grown in three treatments: standard media (YEPD), YEPD plus TCV, and YEPD plus TFV. Microarray gene expression data were examined for variability both within and among microarrays and only the genes which gave results with consistently very low variability were included for further analysis. Four gene expression patterns were examined with the remaining data: 1) genes strongly induced in the TCV only, 2) genes strongly repressed in the TCV only, 3) genes strongly induced in the TFV only, and 4) genes strongly repressed in the TFV only. The greatest number of genes was found to be strongly induced in the TFV (221), while 13 genes were strongly repressed in the TCV, only one gene was strongly induced in the TCV, and no genes were found to be strongly repressed in the TFV. Of the genes strongly repressed in the TCV, two of them (THI7, involved in thiamin transport and IDP2, involved in glutamate biosynthesis) are especially interesting due to both of these processes being potentially linked to autism.