The association of host proteins with viral replicase complexes has been demonstrated in a number of plus-strand RNA viruses (1, 24), including the Bamboo mosaic virus (BaMV). In BaMV it has been reported that chloroplast phosphoglycerate kinase (PGK) (25) and HSP90 (Huang et al., unpublished data) are required for the efficient accumulation of BaMV; where as the identity of the additional factors associated within the BaMV RdRp complex, and the proteins involved in satBaMV RNA replication are not yet been acknowledged. This study identified a host metabolic enzyme namely GAPDH, that interact to negatively regulate the Bamboo mosaic virus (BaMV) and its associated satellite RNA accumulation. The RNA binding properties of GAPDH has already been documented for a number of viruses (9, 14, 29, 41, 53, 56). However, the interaction of GAPDH protein with different viral RNAs results in a functionally different mode of regulation on viral replication and translation. For instance: GAPDH interacts with the JEV NS5 protein indirectly by binding with 3′-ends of JEV, resulting in virus-induced redistribution of GAPDH to control the early stage of JEV replication/translation (53). GAPDH plays a major functional role in the replication of tombusviruses through the retention of the viral minus-strand RNA template in the replication complex in order to promote asymmetric RNA synthesis (48). In contrast, GAPDH inhibits viral replication in the interaction with other viruses. For example: Silencing GAPDH increases TGEV infection by 2-3 times, demonstrating the anti-TGEV activity of this protein (14). Binding GAPDH to the HAV RNA suppresses cap-independent translation due the destabilization of the secondary structure of RNA (55). In our study, a downregulation of GAPDH-C led to a 2 to 3-fold increase in the replication BaMV and satBaMV RNA, indicating that GAPDH-C has an inhibitory effect on BaMV and satBaMV infection. In addition, an increase in BaMV-GFP was observed on inoculated leaves in GAPDH-C silenced N. benthamiana, revealing that GAPDH-C functions in the early stages while the virus is establishing a successful infection of the primary invaded cells. Similarly, when GAPDH-C is transiently expressed, a 70-80% reduction in the accumulation of BaMV as well a considerable downregulation of BaMV-GFP/satBaMV-GFP was observed in N. benthamiana plants. A similar decrease in the accumulation TMV and the size rather than the number of TMV- GFP foci was observed when TARF was transiently expressed in N. benthamiana (52). Together, this appears to imply that the expression of GAPDH-C has a negative effect on BaMV/satBaMV infection.
A previous study, looked at by the researchers, stated that nuclear localization signals are what allow the RNA to enter the nucleus (Wu W, Pante N. 2009). This persuaded them to ask the question of whether or not there was a nuclear localization signal within a viral protein of HCRSV. The localization of P23 was then tested using a transient expression method. The results of their experiment showed that there was a strong signal detected in the nucleus of the Kenaf leaf samples. This proved that P23 was in fact localized in the nucleus and that a nuclear localization signal is present in P23 (Gao R, Liu P, Wong SM. 2012). It was also found that P23 has the ability to bind to carrier proteins that come into the nucleus. This showed that even if P23 was not localized in the nucleus, it could still enter. The mode of entry into the nucleus was discovered to by α-importin (Gao R, Liu P, Wong SM. 2012) . This was discovered by experimenting with a probe of anti-importin α antibody. α-importin was only detected in the protein extract of P23 in the nucleus of the HCRSV-infected Kenaf sample (Gao R, Liu P, Wong SM. 2012). Researchers concluded from their results of the experiments that α-importin, P23, and HCRSV RNA form a complex that enters the nucleus to begin replication of the
Miller, Kenneth R. and Joseph S. Levine. “Chapter 12: DNA and RNA.” Biology. Upper Saddle River: Pearson Education, Inc., 2002. Print.
Feline panleukopenia virus (FPV) is a small (20 nm) autonomous , non –enveloped, icosahedral, single-stranded DNA virus that is approximately 5,120 nucleotides in legnth. The genome encodes for two genes which each form two proteins by alternative mRNA splicing. The non-enveloped capsid is assembled from 60 copies of a combination of the overlapping capsid proteins VP1 and VP2. The virus contains three capsid proteins. The capsids normally enter cells by clathrin-mediated endocytosis. Replication of the virus in the host occurs in cells that are rapidly dividing. FPV can survive in pH ranging from 3 to 9. The virus is highly resistant to most disinfectants (ether, chloroform, acid, alcohol, and heat), but is susceptible to Clorox bleach.
The virus is primarily spherical shaped and roughly 200nm in size, surrounded by a host-cell derived membrane. Its genome is minus-sense single-stranded RNA 16-18 kb in length. It contains matrix protein inside the envelope, hemagglutinin and neuraminidase, fusion protein, nucleocapsid protein, and L and P proteins to form the RNA polymerase. The host-cell receptors on the outside are hemagglutinin and neuraminidase. The virus is allowed to enter the cell when the hemagglutinin/ neuraminidase glycoproteins fuse with the sialic acid on the surface of the host cell, and the capsid enters the cytoplasm. The infected cells express the fusion protein from the virus, and this links the host cells together to create syncitia.
Varicella –Zoster Virus (VZV) is a ubiquitous, double standard DNA virus that belongs to the herpes virus group. Like other herpes viruses, VZV may persist in the body after primary infection .VZV is a virus exists across the globe having a high prevalence in temperate climates. It also has a high prevalence in seasons of late winter and early spring. The primary infection results in Varicella (chicken pox) whereas recurrent infection causes herpes zoster (shingles). The virus is approximately 150 to 200 nanometer in size, is the smallest of the known viruses causing herpes and lacks genes for several proteins found in HSV, which is the prototype of the alpha herpes viruses, such as glycoprotein D (Mandell et al., 2009). The virus has a high sensitivity to temperature and becomes inactivated at approximately 56-60 degrees Celsius (Arvin, 1996). If it is was exposed to such a high temperature the viral envelope would be disrupted making the virus not infectious. Varicella zoster virus produces six or more glycoproteins, such as gB (gpII), gC (gpIV), gE (gpI), gH(gpIII), and gL, which are also expressed on the cell membranes during viral replication (Arvin, 1996). The gE protein is produced abundantly in VZV. The gB protein is the target of neutralizing antibodies and may play a role in virus entry. The gH protein appears to have fusion function, facilitating cell –to-cell spread of the virus.
International Union of Biochemistry and Molecular Biology. [Online].; 2002 [cited 2014 April 21. Available from: onlinelibrary.wiley.com/store.
The life-threatening, smallpox-causing, flu-epidemic-causing, and poorly understood particulates found in our daily lives - viruses - have such a negative connotation. All viruses are not bad, though. Tobacco Mosaic Virus (TMV) is one such virus. It cannot even infect humans, and yet it is so vital to our understanding of viruses that do have human hosts. The Life of a Virus: Tobacco Mosaic Virus as an Experimental Model, 1930-1965 pits TMV as the primary model organism for the entire field of early molecular biology (and thus biochemistry) and plant-based virology. Angela N. H. Creager manages to achieve this lofty goal through examples, biographies, and communications between scientists of the time period
"Virus-Host Cell Interactions during Hepatitis C Virus RNA Replication: Impact of Polyprotein Expression on the Cellular Transcriptome and Cell Cycle Association with Viral RNA Synthesis -- Scholle Et Al. 78 (3): 1513 --." The Journal of Virology. Web. 24 Mar. 2010. .
First, the internalization of the virus was determined. Three stages were identified for the internalization to occur. These stages are as follows: Stage I- actin dependent movement on the cell surface. Stage II- Unidirectional movement toward the nucleus by use of microtubules. At this stage the virus is inside the cell and headed toward the lysosome. Internalization was found to occur at about 190 seconds. Stage III- Bidirectional movement within the cell and is dependent on microtubules as well. It was determined through experimentation that microtubule movement only occurs once internalization of the virus has
The genome encodes 5-proteins: nucleoprotein (N), phosphoprotein (P), matrix protein (M), glycoprotein (G), and polymerase (L). The two major structural components of viruses like rabies that fall under the rhabdoviruses family are: a helical ribonucleoprotein core (RNP) and a surrounding envelope. Rabies is an RNA virus. The arrangements of the five proteins and the RNA genome determine the structure of the rabies virus. The genome is a single-stranded, non-segmented, RNA of about 12kb that is followed by the five proteins.
Rotavirus is a member of the Reoviridae family which contains double-stranded RNA encased in ...
Lindell D, Jaffe JD, Johnson ZI, Church GM, Chisholm SW. 2005. Photosynthesis genes in marine viruses yield proteins during host infection. Nature 438:86-89.
All living things on earth are made up of cells that contain DNA. Deoxyribonucleic acid or DNA is the genetic material of living things that can be found in the nucleus of the cells (Alcamo, 1996). It contains the genes and the genetic codes that contain the information that are essential for life’s functions which are passed from generations to generations. DNA composes of two polynucleotide chains twisted around each other in the form of a double helix. According to Alcamo (1996), each strand of the DNA double helix can act as a template for the synthesis of a new complementary strand as it contains a sequence of nucleotides that is exactly complementary to the nucleotide sequence of its partner strand. DNA replication is semi-conservative. Thus, two identical molecules of DNA are formed during DNA replication of one helix of DNA. Each new molecule of DNA contains one strand of parental DNA which is from the original helix and one strand of new DNA when DNA molecule is copied. DNA replication is a process that all cells must go through and occur before cell division (Corazon, 2010). There are several steps involve during DNA replication which are initiation, elongation, termination and proofreading and correction (refer to Figure 1 in Appendix 1).
DNA REPLICATION WHAT IS DNA - a. DNA is a molecule that has a repeating chain of identical five-carbon sugars (polymers) linked together from head to tail. It is composed of four ring shaped organic bases (nucleotides) which are Adenine (A), Guanine (G), Cytosine (C) and Thymine (T). It has a double helix shape and contains the sugar component deoxyribose. THE PROCESS OF DNA REPLICATION How DNA replicates is quite a simple process. First, a DNA molecule is “unzipped”.
Dengue virus (DENV) is any of the four serotypes that cause the dengue fever or dengue hemorrhagic fever. It is a single positive-stranded RNA virus belonging to the family of Flaviviridae. Its genome is consisted of 11,000 bases that code for three structural proteins, membrane protein M (prM), envelope protein E, capsid protein C, seven nonstructural proteins NS1-NS5, and a short non-coding region on both the 5’ and 3’ ends 2, 6, 19.