Mutations outside the YMDD motif in the P protein can also cause DHBV resistant to Lamivudine.
OBJECTIVE
To observe the Lamivudine resistance character of a DHBV strain in vitro and in vivo, and to analyze if the Lamivudine resistance character is caused by gene mutation or by abnormity of the Lamivudine metabolism.


METHODS
Congenitally DHBV-negative Guangdong brown ducks and duck embryo liver cells were respectively taken as animal and cell model. The Lamivudine-susceptive DHBV and Lamivudine-resistant DHBV (LRDHBV) were infected and Lamivudine was administrated according to the divided groups. The changes of DHBV quantity in the animal and cell model were tested. Three Lamivudine-resistant and two Lamivudine-susceptive DHBV complete genomes were successfully amplified, sequenced and then submitted to GenBank. All the DHBV complete sequences in the GenBank at present were taken to align with the three LRDHBV to analyze the mutational points related to the Lamivudine-resistant mutation.


RESULTS
Both the animal and cell model showed that the large and the small dosage Lamivudine have no significant inhibitory effect on the LRDHBV. Five sequences of DHBV complete genomes were successfully cloned. The GenBank accession numbers of the three sequences of LRDHBV are AY521226, AY521227, and AY433937. The two strains of Lamivudine-susceptive DHBV are AY392760 and AY536371. The correlated mutational points are KorR86Q and AorE591T in the P protein.


CONCLUSIONS
The Lamivudine resistance character of this DHBV strain is caused by genome mutation; the related mutational points are KorR86Q and AorE591T and have no relations with the YMDD motif mutation.
He
Jin-Yang
JY
Tropical Medicine Institute of Guangzhou University of Traditional Chinese Medicine, Guangzhou 510405, Guangdong Province, China. sunny12345678_89@yahoo.com.cn
Zhu
Yu-Tong
YT
Yang
Rui-Yi
RY
Feng
Li-Ling
LL
Guo
Xing-Bo
XB
Zhang
Feng-Xue
FX
Chen
Hong-Shan
HS
D000595:Amino Acid Sequence; D000818:Animals; D002642:Chick Embryo; D004195:Disease Models, Animal; D024882:Drug Resistance, Viral / Q000235:genetics; D004372:Ducks; D015684:Gene Products, pol / Q000235:genetics*; D006509:Hepatitis B / Q000188:drug therapy*; D006515:Hepatitis B virus / Q000187:drug effects* / Q000235:genetics; D019259:Lamivudine / Q000494:pharmacology*; D008969:Molecular Sequence Data; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*
D015684:Gene Products, pol; C066027:P protein, Hepatitis B virus; D018894:Reverse Transcriptase Inhibitors; D019259:Lamivudine