The nucleic acid found in a virus can be UNA or RNA.
On the basis of number of strands present the viruses are categorised as-
(i) Single stranded DNA Bacteriophage ϕ×174, coliphage S13,
(ii) Double stranded DNA-Adenovirus, coliphage T2,T4,T6,T7, lambda coliphage
(iii) Single stranded RNA-TMV, influenza,
(iv) Double stranded RNA-Wound tumour virus, Reovirus etc.
The genetic material in E. coli is double stranded circular DNA.