1. Department of Cancer Biology, Harvard School of Public Health, Boston, MA 02115.
2. Virology Laboratory, CHRU Bretonneau and UER Pharmaceutical Sciences, 37044 Tours, France.
3. Bacteriology-Virology Laboratory, Dakar University, Dakar, Senegal.
4. Electron Microscopy Unit, CHRU Bretonneau, 37044 Tours, France.
5. CHRU Dupuyfren, 87042, Limoges, France.