Arrive Early, Appear Late

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Science  22 Oct 2004:
Vol. 306, Issue 5696, pp. 577
DOI: 10.1126/science.306.5696.577c

Chickenpox is caused by the varicella-zoster virus (VZV), which infects via the respiratory tract before producing the telltale skin rash 2 to 3 weeks later. It is currently assumed that this latency results from incubation of the virus in lymphoid tissue and organs such as the liver, before being transported to the skin as the final stage of a secondary viremia.

Ku et al.challenge this model by showing that the virus, in fact, quickly hitchhikes its way to the skin by infecting T cells. Using immune-deficient mice that had received grafts of human skin, the authors observed that transferred human T cells appeared in the grafts as early as 24 hours after being infected with the virus. Predominantly, these proved to be memory T cells, which is consistent with the observation that such cells are significantly more susceptible to infection with VZV. Potentially, the high rates of recirculation to peripheral tissues shown by memory T cells would benefit the virus by allowing it to access the skin efficiently. On arrival, innate antiviral mechanisms were induced, suggesting that the delay in the appearance of VZV pox lesions may arise from the virus having to overcome local defenses. — SJS

J. Exp. Med. 200, 917 (2004).

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