Controlling Microbial Growth


Viruses are controlled by chemical agents called antivirals that damage virus protein coats or genetic material.

Chemical agents play an important role in controlling the spread of viruses. These agents are called antiviral agents. Unlike bacteria and fungi, viruses are not alive—they do not carry out any metabolic processes and they have no cell membranes or organelles. Thus, many chemical agents that kill bacteria and fungi are not useful for controlling viruses.

Viruses consist only of a strand of nucleic acid (DNA or RNA, depending on the virus) surrounded by a protein coat. They replicate by introducing their nucleic acid into a host cell, tricking the host's cellular machinery into producing more of the virus's genetic material and proteins. Thus, antiviral agents must interrupt these processes.

Agents that denature proteins, such as phenols, can therefore inactivate viruses by damaging the protein coat. A virus with a damaged protein coat has less ability to successfully transfer its genetic material into a host cell. However, the damage must be such that the virus can no longer introduce any genetic material, or the agent is ineffective. Some agents can eliminate some but not all viruses in this way.

Other agents damage the genetic material of the virus. Then, even if the virus is able to inject genetic material into a host cell, the host is not hijacked into producing more of the virus. Alkylating agents, such as ethylene oxide, nitrous acid, and hydroxylamine, are especially useful for this purpose.

The best antiviral agents employ a combination of agents that disrupt viral protein coats and alter viral nucleic acids.