Appearance of HbeAg in an occult persistent hepatitis B virus infection.
Occult hepatitis B virus infection (OBI) is characterized by the presence of ongoing viral replication with very low levels of viremia (<200 IU/ml), and negativity for HBsAg, while the so-called 'false' OBI with higher levels of HBV-DNA that are negative for HBsAg are usually due to the occurrence of mutations of the HBsAg sequence that may alter the recognition by some immunoassays. We describe here a case of occult HBV infection that combines both aspects. A male patient with severe systemic diseases, positive for anti-HBc and anti-HBs and negative for all other HBV markers, including HBsAg, since at least 4 years, showed a positivity for HBeAg at a follow-up control in November 2008; HBV-DNA testing by real-time PCR evidenced very low levels of viremia (<40 IU/ml), direct sequencing of the surface antigen-coding and Pol/RT coding regions allowed the identification of genotype D, serotype adw2, one immune escape mutation (G145R) and no drug resistance mutations. The positivity for HBeAg could be attributed to a superinfection in a naturally immune subject or to reactivation of a latent infection; the mutated virus had a reduced fitness and was therefore able to replicate only at low levels, resulting in a mild form of occult HBV infection.
Department of Laboratory Medicine, G.B. Grassi Hospital, Rome, Italy. concetta.paparella @ aslromad.it
Concetta
C
Paparella
Filomena
F
De Rosa
Roberta
R
Longo
Giuseppina
G
Cappiello
Antonella
A
Ursitti
Marisa
M
Rosa
Massimo
M
Morosetti
Alberto
A
Spanò
D000368:Aged; D004279:DNA, Viral / Q000097:blood / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D006509:Hepatitis B / Q000175:diagnosis* / Q000821:virology; D006510:Hepatitis B Antibodies / Q000097:blood*; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006513:Hepatitis B e Antigens / Q000097:blood*; D006515:Hepatitis B virus / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D008297:Male; D020125:Mutation, Missense; D017422:Sequence Analysis, DNA; D019562:Viral Load
D004279:DNA, Viral; D006510:Hepatitis B Antibodies; D006514:Hepatitis B Surface Antigens; D006513:Hepatitis B e Antigens