Kashif Mehmood-sup-Dr. Najam-us-Sahar Sadaf Zaidi TH-MS-Hepatitis B Viruses with Proecore and Core Region Defects : Analysis of Prevelling Mutant among Pakistani isolates Kashif Mehmood-sup-Dr. Najam-us-Sahar Sadaf Zaidi - IIslamabad ASAB (NCVI) NUST 2011 - xviii, 88 P 30 cm Subjects--Uniform Titles: Virology and Immunology