(c) viruses have very few biochemical mechanisms of their own
Making anti-viral drugs is more difficult than making anti-bacterial because viruses have very few biochemical mechanisms of their own. Virus are considered to be in the twilight zone. They are neither living nor non-living. Besides Viruses do not have any metabolism. This results in no metabolic trail for the antibiotics to trace and follow. Hence anti- bacterial drugs have been developed to tackle bacterial infections, but anti-viral drugs are yet to be manufactured for the same reason, they do not leave any metabolic trail.