Genetically-modified viruses are increasingly being used as vaccines. Such vaccines are often based on a safe and efficacious vaccine virus, such as vaccinia or adenovirus, wherein the viral genome has been modified to include genes coding for immunogenic proteins from other viruses such as HIV or measles. Additionally, viruses such as oncolytic adenoviruses are being used as anti-cancer agents.
The patentability of such viruses will generally be assessed on the basis of whether or not the modification of the viral genome (e.g. the insertion of a heterologous gene) is obvious or not. Factors which might influence such an assessment include the form of the modification (e.g. insertion, deletion, substitution); the identity of any inserted gene or DNA element; and the location of the modification in the viral genome. In all cases, it is desirable to obtain data comparing the effect of the modified virus against that of the unmodified virus, in order to demonstrate to the Patent Examiners that a non-obvious effect is present when the modified virus is used.
Uses of bacteriophages (phages) have expanded considerably in the past decade including as diagnostic agents, therapeutics agents and in food technology. The potential of bacteriophages to be exploited as antimicrobial agents has received particular attention in view of the rapid global emergence of multi-antibiotic resistance in bacterial pathogens.
Phage patent applications are usually centred around the definitions of the phages: these definitions are generally based on the complete genome sequences of the phages or the accession numbers of deposited samples of the phages (i.e. deposited under the Budapest Treaty). The phages may be natural phages or genetically-modified ones.
Issues may arise if the phages are natural products (i.e. their sequences are not modified in any way compared to wild-type sequences). Such natural products are not patentable in the US, unless the phages are combined with other components (e.g. other phages), wherein the combination provides “significantly more” than the individual components.