Virus ssDNA

In eukaryotes, DNA is generally double-stranded (dsDNA) and RNA is generally single-stranded (ssRNA). Exceptions occur in certain viruses, some of which have ssDNA genomes and wime of which have dsRNA genomes.. ... 

Additional viruses that may prove of some use as future viral vectors include adeno-associated virus and herpes virus. Adeno-associated virus is a very small, single-stranded DNA (ssDNA) virus—its genome consists of only two genes. It does not have the ability to replicate autonomously and can do so only in the presence of a co-infecting adenovirus (or other selected viruses). 

The construction of intact virus particles from the genomic DNA and protein subunits is often a complex process. It is simplest for the small filamentous ssDNA viruses (Fig. 7-7). The subunits are synthesized as soluble proteins, which enter the cell membrane, then lose their leader sequences. As the viral DNA coated by the viral gene 5 ssDNA-binding protein enters the membrane, the binding protein is replaced by the coat subunits, 422-424... 

Schneider, D.J., Feigon, I, Hostomsky, Z. and Gold, L. (1995) High-affinity ssDNA inhibitors of the reverse transcriptase of type 1 human immunodeficiency virus. Biochemistry, 34, 9599-9610. 

SSAR, succinic semialdehyde reductase ssDNA, single stranded DNA SSy simian sarcoma virus... 

The structures of ssDNA bacteriophages ( X174 and G4 have been reported in mature and provirus forms (Dokland et al, 1997 McKenna et al, 1992b, 1996). The mature viruses are T=1 with 60 copies each of the F, G, and (small J) proteins, and 12 copies of the H protein. Both the F and G proteins are classic viral jelly-roll structures. It is the F protein that occupies the positions homologous to the (+)ssRNA capsids. At 430 residues, the F protein is closest in size to the parvoviral capsids, and achieves its size through large loop insertions, primarily in the EF and HI... 

Parvoviridae is a family of small icosahedral, nonenveloped animal viruses that contain a linear ssDNA genome of approximately 5000 bases with short unique terminal palindromic sequences that fold back on themselves to form hairpin duplexes (van Regenmortel et al, 2000). They are further classified into two subfamilies, Parvcwirinae and Densovirinae, and various genera depending on host specificity, strand specificity of the genomic ssDNA, and on whether helper viruses are required for productive infection (dependoviruses). Members of the Parvoviridae... 

Genome entry model, of single-stranded DNA (ssDNA) viruses, 237 Genome packaging... 

Paramyxovirus fusion protein, negative-strand RNA viruses and, 162 Pariacoto virus, 223 Particle reconstruction images, 198 Parvoviridae family, 238-240 Desovirinae subfamily of 239 Parvovirinae subfamily of 239 of single-stranded DNA (ssDNA) viruses, 242... 

Spodoptera jirugiperda (Sf), 8 ssDNA viruses. See Single-stranded DNA (ssRNA) viruses... 

DNA replication. New virus particles assemble in the nucleus, packaging either plus or minus ssDNA viral genomes, and are released from the cell together with the helper vims. [For more details see (1).]... 

Once the gpl20 envelope protein of HIV binds to the CD4 antigen and chemokine receptor on the T cell, the viral envelope fuses with the host cell s plasma membrane. The two RNA strands are released into the cytoplasm. Reverse transcriptase, a heterodimer with several enzymatic activities, then catalyzes the synthesis of an ssDNA using the vRNA as a template. The heterodimer s RNase activity then degrades the vRNA. The same protein produces a double-stranded vDNA by forming a complementary strand of the ssDNA. Viral integrase integrates the vDNA into a host cell chromosome. The proviral DNA remains latent until the specific infected T cell is activated by an immune response. The proviral DNA can then direct the cell to synthesize viral components. Newly synthesized viruses bud from the infected cell. 

After a retrovirus binds to the host cell, and its envelope fuses with the plasma membrane, the viral capsid is released into the cytoplasm. The viral reverse transcriptase synthesizes an ssDNA copy of the viral genome. This enzyme activity also converts the ssDNA into a double-stranded molecule. The dsDNA is then translocated into the nucleus where it integrates into a host cell chromosome. The integrated provirus is replicated each time the cell undergoes cell division. After the provirus is activated, new virus is created as newly synthesized vRNA and viral proteins are packaged with cell membrane and released from the host cell by a budding process. 

The adeno-associated virus (AAV) is a nonpathogenic, ssDNA virus belonging to the Parvoviridae family of viruses. This virus has two genes The cap gene encodes for three viral coat proteins, and the rep gene encodes for four proteins involved in viral replication and integration. This virus needs additional genes to replicate that are provided by the helper virus, which usually is the adenovirus or herpes virus. Interest in this virus as a vector arose from the... 

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