The present disclosure relates to a type B adenovirus wherein E4orf4 is deleted or non-functional and generally having a DNA sequence in the E3 region, in particular viruses of formula (I), compositions containing the virus, for example pharmaceutical formulations of the virus, processes for making the viruses and the compositions and use of any one of the same in treatment, particularly in the treatment of cancer, such as colorectal cancer and ovarian cancer.
