Negative strand

Marc Van Regenmortel I m trying to apply your idea to viruses and their replication. If you have a single-strand virus, lets call it plus , it gives rise to a minus and plus double strand in your case it s a half picture which gives the full picture of the other half without material overlap or actually only half of the overlap. Then the negative strand is used to make more positive strands, and there is no material overlap anymore. Now how does that fit into your scheme ... 

The viral RNA polymerase first transcribes the incoming positive-stranded 42 S RNA into negative-stranded 42 S RNA, which in turn serves as a template for the synthesis of both new positive-stranded 42 S RNA molecules and 26 S RNA molecules. The transcription of the 26 S RNA is initiated internally on the negative-stranded 42 S RNA. RNA replication seems to take place on membranes in characteristic cytoplasmic vacuoles, called cytopathic vacuoles I (CPV I), which appear soon after infection and are not seen in uninfected cells (Grimley et al., 1968, 1972 Friedman et al., 1972). The detailed mechanism of the RNA replication will not be dealt with here (for reviews see Strauss and Strauss, 1977 Kaariainen and Soderlund, 1978 Kennedy, 1980). 

There is a wide variety of vectors used to deliver DNA or oligonucleotides into mammalian cells, either in vitro or in vivo. The most common vector systems are based on viral [retroviruses (9, 10), adeno-associated virus (AAV) (11), adenovirus (12, 13), herpes simplex virus (HSV) (14)] andnonviral [cationic liposomes (15,16), polymers and receptor-mediated polylysine-DNA] complexes (17). Other viral vectors that are currently under development are based on lentiviruses (18), human cytomegalovirus (CMV) (19), Epstein-Barr virus (EBV) (20), poxviruses (21), negative-strand RNA viruses (influenza virus), alphaviruses and herpesvirus saimiri (22). Also a hybrid adenoviral/retroviral vector has successfully been used for in vivo gene transduction (23). A simplified schematic representation of basic human gene therapy methods is described in Figure 13.1. 

A schematic diagram of an influenza virus particle that illustrates its constituent components and morphology. The surface antigens hemagglutinin and neuraminidase are attached to the lipid and matrix protein shell that encapsulates the eight negative-stranded RNA genes of the virus and associated nucleoprotein and polymerase. 

Canine parvovirus, first identified in 1978, is now endemic.455,456 Childhood fifth disease is also caused by a parvovirus.456,457 When these single-stranded DNA viruses infect cells a double-stranded replicative form of DNA arises by synthesis of the complementary negative strand alongside the original positive DNA strand. Many copies of the replicative form are then synthesized. The negative strands of the replicative forms serve as templates for synthesis of numerous new positive strands that are incorporated into the progeny viruses. The whole process may take only 20 minutes. Some parvoviruses are unable to reproduce unless the cell is also infected by a larger adenovirus. 

Large viruses of 80 -100 nm diameter bearing 8-10 spikes at the vertices of the icosahedra cause influen-za 509,510 mumps, measles, and related diseases. The internal structure must be complex. Only 1% of the virus is RNA, and that consists of several relatively small pieces. These are negative strand viruses whose RNA is of the opposite polarity to the mRNA. The latter must be formed by transcription from the negative strand. The viruses carry their own RNA polymerase for this purpose. Of even more complex structure are the bullet-shaped rhabdoviruses which cause rabies and vesicular stomatitis.511 The diameter of these viruses is 65-90 nm and the length 120-500... 

After the formation of the RF, the bacteriophage-encoded gp2 cleaves the positive strand within the intergenic region, which rolls off from the negative strand. During this process, both strands are again replicated to produce double-stranded RFs. This type of replication, known as the rolling circle... 

Negative-strand RNA viruses are enveloped and larger than those considered so far. Genomes are packaged into a helical nucleoprotein complex. Envelopes contain one or two glycoproteins for which structures are available for hemagglutinin (HA) (Wilson et al, 1981) and neuraminidase (NA) (Colman et al, 1983) from influenza A (Table III). 

M], negative-strand RNA viruses and, 161 M2, negative-strand RNA viruses and,161-162... 

Negative-strand RNA viruses, 158-163 ebola virus matrix protein/ glycoprotein, 162-163 hemagglutinin-neuraminidase and, 162 influenza A and, 158-163 Ml and, 161 Ms and, 161-162 neuraminidase and, 161 paramyxovirus fusion protein and, 162 Neuraminidase, negative-strand RNA viruses and, 161... 

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... 

The way in which the viral genome is replicated depends entirely on the nature of the nucleic acid carried by the virus. Positive strand RNA viruses (e.g. poliovirus) can use the parent RNA directly as mRNA, after the acquisition from the host cell of a terminal sequence enabling immediate translation. With negative strand RNA viruses (e.g. influenza virus), a positive RNA strand complementary in base sequence to the parent RNA has to be transcribed using an RNA-dependent RNA polymerase carried by the virus, as eukaryotic cells do not possess such enzymes. 

The assay described herein is capable of detecting at least three of the multiple functions of the polymerase. These are the initiation of DNA synthesis, the translocation of the initiation DNA-po/ complex, and the extension of the genomic negative-strand DNA using a portion of the pregenomic RNA as template. The initiation of DNA synthesis by DHBV pol is unusual in that the polymerase protein acts as a primer and the first nucleotide incorporated (dGTP) is covalently linked to a tyrosine residue near the N-terminus of the... 

Viruses which contain an RNA genome can be classed as positive and negative-stranded viruses depending on whether their genome RNA serves directly as mRNA (positive) or requires RNA transcription to synthesize mRNA molecules (negative). Dramatic discoveries have been made in each of these virus group. 

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