Infectious Agents
Case 3

Clinical Presentation
Electron Microscopy
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Electron Microscopy of Infectious Agents

Case 3-Adenovirus in Pleural Fluid Cultures.

Discussion

Adenovirus is becoming an increasingly important pathogen in patients with compromised immune systems. No therapy has been shown to be effective against adenovirus, and invasive disease is usually fatal ¹. Because adenovirus can persist for months or years in patients whose immune systems are not compromised, reactivation of a persistent infection may occur when the immune system is conditioned for solid organ or bone marrow transplantation. This case characterizes an adenovirus positive B-cell line established from an immunocompromised patient with both EBV-associated BLPD and adenovirus pneumonia. The fact that the recipient and donor were positive for EBV-specific antibody before the transplant suggests that the BLPD developed as a result of reactivation of latent EBV infection.

Transmission electron microscopy can be a useful methodology to identify the intranuclear viral inclusions, and to visualize cytoplasmic aggregation of virus which is not detectable at the light microscopic level ². In this case, viral particles are found in unusual abundance in the cytoplasm, which may reflect continuous viral production without inhibition of cellular protein synthesis, with the virions exiting the nucleus after assembly rather than by nuclear lysis. The unusual paracrystalline inclusions that are present within the nuclei and cytoplasm of the cells may represent aggregation of excess viral structural proteins.

References:

1. Flomenberg, P., Piaskowski, V., Harb, J.M., et al.: Spontaneous, persistent infection of a B-cell lymphoma with adenovirus. Jour. Med. Virol. 48:267-272, 1996.
2. Orenstein, J.M.: The role of electron microscopy in infectious disease diagnosis. The J. Histotechnol 18:211-224, 1995.

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