<prompt> The best way of detecting the presence of viruses in the infected cell culture is:Cytopathic changes in culture cellsPresence of viral protein in the infected monolayerHaemagglutination testHaemagglutination inhibition test  <response>: The changes in cell morphology caused by infecting virus are called cytopathic effects CPE.In order to view these cellular changes under light microscopy, the cell cultures have been stained with hematoxylin, a basic dye, and eosin, an acidic dye. Common examples are rounding of the infected cell, fusion with adjacent cells to form a syncytia polykaryocytes, and the appearance of nuclear or cytoplasmic inclusion bodies. 