Residual Tannic Acid Destroys Virucidal Properties of Iodophor.

Surface de-adhesion and disinfection of eggs at hatcheries are critical steps in successful fry culture; however, little is known about the effects of the combination of these compounds on the efficacy of egg surface disinfection. We examined the effect of tannic acid on detection of viral hemorrhagic septicemia virus (VHSV) type IVb alone and in the presence of iodophor under in vitro conditions. We confirmed that tannic acid inhibits the quantitative reverse-transcriptase polymerase chain reaction assay developed in our laboratory and that it binds to VHSV, reversibly decreasing infectivity. Surprisingly, we also found that when combined with iodophor, tannic acid destroys the ability of either compound to inhibit infectivity. While we still strongly encourage the use of iodophor for its antiviral, bactericidal, and fungicidal properties, our results suggest that when tannic acid is used prior to disinfection with iodophor, it must be very thoroughly rinsed to ensure that it does not interfere with the disinfectant properties of iodophor. [ABSTRACT FROM AUTHOR]