ABSTRACT
Virus titration is an important step required on viral vaccines quality control. "Plaque assay", which emplosys several types of everlay media, is usually used on viral titrations. In this paper we describe the use of apioca as an overlay media. Firstly, the toxicity of Tapioca was tested on Vero cells inoculated or not with the Yellow Fever virus (YF) 17 DD vaccine strain. Secondly, different batches of the 17 DD virus using the Tapioca. Tapioca was also shown to be a suitable overlay to be used in thermostability and plaque reduction neutrabilization tests. Other systems could benefit from the use of Tapioca as an overlay, since it was possible to titer. Measles virus in Vero cells. Tapioca is a cheap Brazilian product, is locally available, easy to use, and reliable. Its use is suggested