The Avian HBV RNA encapsidation signal epsilon (AHBV epsilon) is an RNA structure that is shown to facilitate encapsidation of the pregenomic RNA required for

viral replication Viral replication is the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. Through the generation of abundant copies of its genome an ...

. There are two main classes of encapsidation signals in avian hepatitis B viruses - ''

Duck hepatitis B virus ''Duck hepatitis B virus'', abbreviated DHBV, is part of the genus ''Avihepadnavirus'' of the ''Hepadnaviridae'', and is the causal agent of duck hepatitis B. DHBV is a small DNA virus with a diameter of 40–45 nm. The viral envelope is ...

'' (DHBV) and ''

Heron hepatitis B virus ''Avihepadnavirus'' is a genus of viruses, in the family ''Hepadnaviridae''. Birds serve as natural hosts. There are three species in this genus. Diseases associated with this genus include: hepatitis, hepatocellular carcinomas (chronic infectio ...

'' (HHBV) like. DHBV is used as a model to understand human '' Hepatitis B virus''. Although studies have shown that the HHBV epsilon has less pairing in the upper stem than DHBV, this pairing is not absolutely required for DHBV infection in ducks. DHBV epsilon consists of a stem structure, a bulge and an apical

loop Loop or LOOP may refer to: Brands and enterprises * Loop (mobile), a Bulgarian virtual network operator and co-founder of Loop Live * Loop, clothing, a company founded by Carlos Vasquez in the 1990s and worn by Digable Planets * Loop Mobile, an ...

(Fig. 1). The RNA structure was determined by chemical probing, NMR analysis and by mutagenesis. HHBV epsilon also consists of a stem structure, a bulge and an apical loop (Fig. 2). The RNA structure has been determined by chemical probing and by mutagenesis. However, it has less base pairing in the upper stem than DHBV epsilon. Recent NMR analysis of both the HHBV and DHBV epsilon have shown that the apical loop to be capped by a stable well-structured UGUU

tetraloop Tetraloops are a type of four-base hairpin loop motifs in RNA secondary structure that cap many double helices. There are many variants of the tetraloop. The published ones include ANYA, CUYG, GNRA, UNAC and UNCG. Three types of tetraloops are ...

. In the

Rfam Rfam is a database containing information about non-coding RNA (ncRNA) families and other structured RNA elements. It is an annotated, open access database originally developed at the Wellcome Trust Sanger Institute in collaboration with Janel ...

database a single

covariation model {{More footnotes, date=July 2021 Harold Kelley's covariation model (1967, 1971, 1972, 1973) is an attribution theory in which people make causal inferences to explain why other people and ourselves behave in a certain way. It is concerned with both ...

(AHBV_epsilon box right) best discriminates between the true instances of the element in sequence databases and background. The

secondary structure Protein secondary structure is the three dimensional conformational isomerism, form of ''local segments'' of proteins. The two most common Protein structure#Secondary structure, secondary structural elements are alpha helix, alpha helices and beta ...

diagram is a computer generated view of the structure with highly conserved bases shown in red. It includes the major elements shown in Figures 1 and 2.

References

External links

* Cis-regulatory RNA elements Hepadnaviridae {{molecular-cell-biology-stub

See also

References

External links