Q:How do we fight viruses?

A:Virus particles are invisible, about one millionth of an inch in diameter. They don’t have the biochemicals necessary to live; instead, they come to life by finding a suitable host cell, hijacking its life-giving and reproductive machinery and disabling or even destroying it in the process. But in order to invade and infect humans, viruses have to get past a fierce defender, the immune system, which possesses the ability to detect foreign invaders and interpret the telltale “protein signature” on the surface of cells to differentiate and destroy disordered cells.

The first layer of defense against invasion is intact skin and mucous membranes. Viruses can survive on the skin and on mucous membranes and exploit breeches or breaks in their integrity in order to gain entrance to bodily tissues and host cells. (In dengue fever mosquitoes can penetrate the skin and can introduce viral particles directly to the underlying tissue.)

The next layer of defense is tissue beneath the skin’s surface and mucous membranes. The subsurface tissues have spiny-surface cells that are extremely efficient at alerting the rest of the immune system to the presence of foreign material. Specialized cells and chemicals in the skin and subskin tissues provide a highly complex network of interconnected defense surveillance that some scientists have likened to a fortress of old (that is, well-trained troops), an array of weapons, a well-defined battle plan, and contingency strategies that enable rapid and effective dealing with any breach of its walls. This is the innate immune system.

An additional layer of defense is the cell membrane itself. To gain access to the human cell’s interior, viruses must first bind to a compatible receptor on the cell’s surface that’s normally used for some legitimate function. Without an appropriate or available host receptor, viruses cannot enter. This interaction is very specific and determines which hosts, and cells (and organs) within the host, can be infected by a particular virus. Some viruses don’t enter host cells but instead inject their contents inside after attachment to the membrane.

Once inside, the virus usurps the control center and directs everything toward its own viability through replication. The subsequent barrage of newly replicated viruses in the blood induces a greater immune reaction, and in the process of fighting, the body produces a wide variety of countermeasure chemicals, some of which produce the symptoms of infection.

Fever is evidence of the battle and actually helps the body fight the infection. This phase of the immune response continues until the viruses are eliminated from the body. Specific viruses act differently; for example, the polio virus releases toxins that destroy nerve cells (often leading to paralysis), while HIV (AIDS virus) targets and destroys immune cells, decreasing the body’s ability to defend itself.

General principles to protect ourselves against the invisible offenders include avoiding contact with them, destroying them with soapy water before they enter the body, keeping the immune system functioning optimally through living healthfully and managing stress, and being a loving neighbor by avoiding spreading viruses to others, by God’s grace.

Peter N. Landless, a board-certified nuclear cardiologist, is director of the General Conference Health Ministries Department. Zeno L. Charles-Marcel, a board-certified internist, is an associate director of Adventist Health Ministries at the General Conference.