Mass Transit for Viruses

Researchers at the National Heart, Lung, and Blood Institute have found a never-before-seen means of viral replication: multiple polioviruses traveling together. It is essentially a reversal of a tenet of virology that viruses act independently.

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Following the rule about strength in numbers, the benefits to the viruses may be efficiency and better survival, the researchers say. By arriving as a group to an uninfected cell, the group infects more efficiently than if each virus was acting individually. Also, once inside the cell, the viruses are better able to survive as a group and, thus, reproduce more efficiently.

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After reproducing, multiple viral particles are enclosed in a membrane derived from the cell and exit without bursting the cell, the study found. “Cloaking” themselves in this way may allow them to “travel in disguise,” the study suggests, and appear to immune cells not as foreign invaders but as “self.” Although the membrane may protect the viruses from the body’s immune system, it does not necessarily protect them from drugs. The researchers say the membrane contains particular fat molecules that drugs can block, preventing the viral clusters from infecting cultured cells.

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The newly discovered pathway may also operate in other enteroviruses besides polioviruses, such as those responsible for myocarditis and the common cold.