Original Articles: Viral Hepatitis

liver411

HEPATOLOGY
November 2003 . Volume 38 . Number 5


Deficiency in virion secretion and decreased stability of the hepatitis B
virus immune escape mutant G145R

Tatyana Kalinina1,2 ,Alicja Iwanski1
Hans Will1 ,Martina Sterneck1,3

   Abstract
Hepatitis B virus with a G145R mutation in the small surface protein is
considered the quintessential immune escape mutant because it frequently is
found in vaccinated individuals with breakthrough infections and liver
transplant recipients under anti-hepatitis B surface antigen (HBsAg)
immunoglobulin prophylaxis. Nowadays the prevalence of the variant
progressively increases. However, because spread of a virus depends not only
on immune pressure but also on the viral phenotype, we investigated the
biologic properties of the G145R variant. The G145R mutation was introduced
into wild-type (Wt) virus genome by in vitro mutagenesis. After transfection
into human hepatoma cells, the DNA, RNA, and protein synthesis and viral
secretion ability of the mutant were studied. Furthermore, cotransfection
studies were performed with the G145R variant and a Wt virus S-protein
expressing construct and vice versa. Production and stability of viral
messenger RNAs (mRNAs), DNA, and proteins were not affected by the G145R
mutation. In contrast, secretion of mutant virions was reduced
significantly. Only 20% of virions were found in the medium of G145R
variant-transfected cells compared with Wt virus. Furthermore, mutant
virions were more sensitive to detergent treatment suggesting a diminished
stability. In cotransfection studies, Wt virus S-protein rescued secretion
of mutant virions, whereas mutant S-protein had a transdominant negative
effect on secretion of Wt virus. Both mechanisms may support persistence of
the defective mutant in a mixed population with Wt virus. In conclusion, the
significant defect of the G145R mutant for secretion of infectious virions
and the diminished stability of mutant virions may limit global spread of
the mutant. (HEPATOLOGY 2003;38:1274-1281.)

   Publishing and Reprint Information
From the 1Heinrich-Pette-Institute for experimental Virology and Immunology
at the University of Hamburg, Hamburg, Germany; the 2Institute of Virology,
Moscow, Russia; and the 3University Hospital Hamburg Eppendorf, Hamburg,
Germany.
Received May 7, 2003.
Accepted August 18, 2003.Supported by the Bundesministerium für Forschung
und Technik (01KI9558) and the Deutsche Forschungsgemeinschaft (STE
970/1-2).
Address reprint requests to: Dr. Martina Sterneck, Universitätskrankenhaus
Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany. E-mail:
[email protected] ; fax: (49) 40-42803-6861.
Copyright © 2003 by the American Association for the Study of Liver
Diseases.
0270-9139/03/3805-0026$30.00/0
doi:10.1053/jhep.2003.50484