1. Department of Virology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
2. Central Virology Laboratory, Public Health Laboratories, Chaim Sheba Medical Center, Tel Hashomer, Israel.
3. Ben Gurion University, Soroka Medical Center, Beer Sheva, Israel.
4. Brown School of Public Health and Community Medicine, Hebrew University-Hadassah Medical School, Jerusalem, Israel.