Double-stranded RNA and

A virus-specific RNA RNA polymerase is needed, since the cell RNA polymerase will generally not copy double-stranded RNA (and ribosomes are not able to translate double-stranded RNA either). A wide variety of modes of viral mRNA synthesis are outlined in Figure. By convention, the chemical sense of the mRNA is considered to be of the plus (+) configuration. The sense of the viral genome nucleic acid is then indicated by a plus if it is the same as the mRNA and a minus if it is of oppposite sense. If the virus has double-stranded DNA (ds DNA), then mRNA synthesis can proceed directly as in uninfected cells. However, if the virus has a singlestranded DNA (ss DNA), then it is first converted to ds DNA and the latter serves as the template for mRNA synthesis with the cell RNA polymerase. 

Alexopoulou, L., et al., Recognition of double-stranded RNA and activation of NF-kappaB by Toll-like receptor 3, Nature. 413, 6857, 732, 2001. 

The knowledge of the primary structure was the basis for the construction of models of the secondary structure of the RNA molecules. Different approaches have been used in several laboratories to get experimental support for developing secondary structure models for example, chemic modification of the RNA, treatment with single- or double-strand-specihc nucleases, intramolecular RNA cross-linking, isolation and sequence analysis of double-stranded RNA, and, last but not least, comparison of ribosomal RNA sequences from different organisms (reviewed by Brimacombe et al., 1983). 

The RNA (+) strands present in many RNA viruses often serve immediately after infection as a messenger RNA. However, replication requires formation of (-) strands of viral RNA from which new (+) strands can be transcribed for assembly into new virus particles. Other RNA viruses contain (-) strands of RNA or double-stranded RNA and, therefore, have significantly different life cycles.259... 

The second eIF-2-specific kinase appears to be present at low levels in most mammalian cells. This kinase is activated by double-stranded RNA and for this reason has been named the double-stranded RNA-activated inhibitor (DAI). DAI may play a role in defending cells against invasion by viruses. 

The x-ray diffraction data used by Watson and Crick was obtained from fibers of DNA that were prepared under conditions of high humidity. At lower humidities (<75 percent), a fiber of DNA will shorten. This is a result of a change to the A form, in which the base pairs are not perpendicular to the helix axis they are tilted about 20°, and the pitch is reduced to 2.8 nm with 11 base pairs per turn. While the B-form of the helix is the predominant form in cells, double-stranded RNA and DNA/RNA hybrid molecules generate the A form of the helix. 

Munroe SH, Zhu J (2006) Overlapping transcripts, double-stranded RNA and antisense regulation a genomic perspective. Cell Mol Life Sci 63 2102-2118... 

On the other hand, extrinsic stimuh are often delivered by viruses and bacteria. Bacterial products like lipopolysac-charide (LPS) and DNA with motifs of unmethylated CpG cUnucleotides are extremely potent inducers of neuroinflammation. AdcUtionally, viruses themselves, or their products like retroviral coat protein gp4l and gpl20, double stranded RNA, and transcription factors hke Tat, also induce inflammatory responses in brain cells. 

Mice have been used extensively to examine virus host interactions, and to examine virus-induced encephalitis. The adaptive immune response plays a crucial role in controlling WNV infections in mice, including encephalitis (Diamond et al., 2003 Shresta and Diamond, 2004 Wang et al., 2003). WNV infection leads to a Toll-like receptor 3-dq3endent inflammatory response, which promotes brain penetration of the virus, neuronal injury, and enhanced encephalitis (Wang et al., 2004). Since Toll-like receptor 3 recognizes double-stranded RNA and promotes an innate immune response, this finding... 

Recently it has been shown that the double-stranded RNA and its thermally denatured form behave in a similar manner to native and denaturated DNA [109]. Pulse-polarographic analysis in connection with a gel electrophoresis can be used for testing double-stranded RNA-samples prepared for biological experiments (interferon-inducing and antiviral activities). 

Zabalgogeazcoa I, Benito EP, Ciudad AG, Criado BG, Eslava AP, Double-stranded RNA. and virus-like particles in the grass endophyte Epichloe festucae. Mycol Res 102 914-918, 1998. 

A form A polynucleotide in the A form is a right-handed helix, too (Figure 4.15d). The A form is found in double-stranded RNA and in DNA-RNA hybrids. 

A form found in double-stranded RNA and RNA/DNA hybrids Lack of steric hindrance in B DNA enables it to accommodate water better than A form. 

Indicate the role of deoxyribose puckering in determining the structural differences between A-DNA and B-DNA helices. Compare the structures of double-strand RNA and RNA-DNA hybrids with that of the A-DNA helix. 

Phagicin, from A-pha infected E. coli K-12 [133] and an extract from Haemophilus irifluenza type B [134] are possibly double-stranded RNAs, and may therefore act by interferon induction. 

Langland JO, Pettifotd S, Jiang B et al. Products of the porcine group C rotavirus NSP3 gene bind specifically to double-stranded RNA and inhibit activation of the interferon-induced protein kinase PKR. J Virol 1994 68 6) 3821-3829. 

Photolysis of the ketone-functionalised RNA fragment (4) through a Norrish I process generates the 5,6-dihydrouridin-5-yl radical, which is the formal product of hydrogen atom addition and a model for hydrojyl radical addition to the uracil base. The photogenerated radical produces direct strand scission preferentially in double stranded RNA and in the absence of ojq gen. ... 

Clemens, M. J., Safer, B., Merrick, W. C., Anderson, W. F., and London, I. M., 1975, Inhibition of protein synthesis in rabbit reticulocyte lysates by double stranded RNA and oxidized glutathione Indirect mode of action on polypeptide chain initiation, Proc. Natl. Acad. Sci. USA 72 1286. 

Sen, G. C., Taira, H., and Lengyel, P., 1978, Interferon, double-stranded RNA and protein phosphorylation. Characteristics of a double-stranded RNA-activated protein kinase system partially purified from interferon-treated Ehrlich ascites tumor cells, J. Biol. Chem. 253 5915. 

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