Introduction Potato virus X (PVX) is a plant RNA virus. Its infection cycle includes invasion of the host plant, RNA replication, translation of viral proteins, cell-to-cell movement and release of new virions. Upon infection, PVX releases its plus-strand RNA genome from the virion and produces a viral replicase using host translation machinery. The replicase synthesizes minus-strand RNA. Subsequently new plus-strand genomic RNA (gRNA) and subgenomic RNAs (sgRNAs) are produced. Movement and coat proteins are translated from the sgRNAs for encapsidation and movement through plasmodesmata. In this mini-review, all aspects of the virus infection cycle of PVX are discussed. Classification Potato virus X (PVX) is a small non-enveloped virus, which has a monopartite plus-strand RNA genome. Therefore it belongs to class IV of the Baltimore system. PVX is a member of the Potexvirus genus. Along with eight other genera, this genus belongs to the Alphaflexiviridae family [1]. Virion morphology and content PVX forms small filamentous virions which have a deeply grooved surface [2]. The flexuous filaments consist of a single plus-strand genomic RNA coated with viral coat protein (CP). The helical structure has a pitch of 3.6nm and contains 8 7/8 CP subunits per turn [3]. The full-length filaments have a model length of 515nm with a diameter of 13nm [4]. CP consists of a single domain with high α-helical content [4]. The N-terminal part this domain is surface exposed whereas the C-terminal region buried in the virion. Several experiments indicate the CP is an O-glycoprotein. Equal amounts of galactose and fructose residues are O-linked to an acetylated serine residue at the N-terminal region [2]. This mediates the formation of a structured... ... middle of paper ... ...ut 10%. This is despite of obtaining high virus titers. Symptomless plants are regarded as carriers of PVX and are an important source of infection. Under more severe conditions, necrotic streaks and severe mosaic, crinkling and rugosity of the leaves can occur. Especially upon mixed infections with potato virus Y (PVY), the yield loss can be up to 50%. Several potato plants carry resistance genes against PVX. Up to date two resistance genes have been identified. One gene product mediates salicylic acid systemic defense responses, whereas the other encodes the Rx protein. This protein has a nucleotide binding-site (NBS) and a leucine-rich repeat (LRR). The native fold of Rx confers an inactive conformation. Upon interactions with the viral CP, Rx partially unfolds, thereby its NBS-LRR domain [27]. This activates the signaling cascade mediating virus resistance.
Modern biotechnology was born at the hands of American scientists Herb Boyer and Stain Cohen, when they developed “recombinant deoxyribonucleotide, (rDNA), [1] for medicinal purposes. Subsequently, biotechnologists started genetically engineering agricultural plants using this technology. A single gene responsible for a certain trait, from one organism (usually a bacterium) is selected altered and then ‘spliced” into the DNA of a plant to create an agricultural crop consisting of that...
Polyoma viruses infect mammals causing tumors and cancer. Similarly to polyoma viruses, SV40 contains a DNA that is associated with histones in a circular complex containing 20- 22 nucleosomes (Varshavsky et al., 1977). SV40 DNA is located in a 50 nm capsid which is composed of homopentameters of the major capsid protein, VP1 (43 kilo Daltons) associated with one of the minor structural proteins VP2 or VP3. Under physiological salt and pH conditions, VP1 alone remains disassociated, and at pH 5, it assembles into tubular structures. Between pH 4 and pH 7, VP2 allows the VP1 pentameters to assemble in spherical particles and incorporates VP1. Furthermore, the virus has an icosahedral symmetry and contains 72 pentameters (Liddington et al., 1991). Figure 1shows the proposed structure of SV40 DNA and the length of each region within the virus. The diagram highlights the arrangement of the early and late regions. Furthermore, it shows the clockwise and counter clockwise symmetry of the large T antigen (TAg), small T antigen (tag), and the major capsid proteins within the virus.
Cytomegalovirus (CMV) is the most common virus in the United States that can infect almost any individual. Cytomegalovirus is also referred to as Herpesvirus-5, which belongs to a branch of Herpesviridae family. Herpesviridae has a spherical shape that contains four significant elements that are important to the viron. The four elements are the core, tegument, capsid and the envelope. Alphaherpesvirinae, Betaherpesvirinae and Gammaherpesvirinae are three subfamilies which belong to Herpesviridae. Cytomegalovirus belongs to the Betaherpesvirinae family, which also include Muromegalovirus and Roseolovirus. The Alphaherpesvirinae subfamily includes Simplexvirus, Varicellovirus, Mardivirus and Iltovirus genera. The Gammaherpesvirinae subfamily contains Lymphocryptovirus and Rhadinovirus genera. The diameter size of the virus is based on each specific family; however, the core remains the same throughout the species, which contains single layer of double stranded DNA tightly condensed in the capsid. In the tegument component, there are 30 or more viral proteins that are shapeless that encompass the capsid. Out of the four major components, the tegument has the most poorly defined structure. On the other hand, the capsid is a well-defined structure that is an icosahedron, which is composed of 162 capsomeres, 12 of which are pentons and 150 are hexons (1). Last but not least, the liquid envelope surrounds the tegument with approximately 10 glycoprotein and cellular proteins. Each subfamily under the herpesviriade has its own arrangement between the liquid envelop and the tegument layer.
Orthopoxvirus variola is the virus responsible for the well-known smallpox disease. It belongs to the Poxviridae family which is further split into the subfamilies Entomopoxivirinae which only affects insects, and Chordopoxivirinae which infects vertebrae (Hughes). It is in group one of the Baltimore Classification since it possesses double-stranded DNA. This group also includes viruses in the Herpesviridae family, certain bacteriophages, as well as the mimivirus. The linear genome consists of approximately 186 kb pair and, like all orthopoxviruses, is about 200 nm in diameter (Li; Riedel). Virus particles may be enveloped, but the majority will be nonenveloped when released from a lysed cell, ready and capable to affect another. Extracellular enveloped viruses evolve from their precursors intracellular enveloped virus and cell-associated enveloped virus and contain proteins that aid the virus in neutralizing host cell antibodies to enhance virus spread (Smith). Entrance into the host cell may be accomplished by fusion of endocytosis, contingent on the particular strain. Host cell cytoplasm is the site of poxvirus replication, therefore host nuclear enzymes are unavailable to the virus; to overcome this, DNA-dependent RNA polymerase enters the host with the virus (Hughes).
Like other negative-stranded RNA viruses, the G protein of rabies virus binds to the host cell membranes and penetrates into the host cytoplasm by pinocytosis. The virions are composed of cytoplasmic vesicles, fuse to cytoplasmic membrane and release RNP into the cytoplasm. The core starts primary transcription of the five complementary monocistronic messenger RNAs by using the virion-associated RNA-dependent RNA polymerase. Each mRNA is translated to an individual viral protein. After synthesis and replication of the genomic RNA, the full length, positive-stranded RNA is completed and becomes the template for the next negative-stranded RNA. In the assembly process, the N-P-L complex encapsulates negative-stranded genomic RNA to be made up of RNP core and the M protein consists of a capsule or matrix that su...
RSV is an enveloped, cytoplasmic, pleomorphic virus with negative single stranded RNA (3). This virus belongs in the paramuxoviridae family and in the subfamily Penumovirinae. It has a single serotype and two antigenic subtypes, A or B. In total, 8 out of the total ten RSV proteins are seen in infected cells and virions, eight being structural and two being non-structural (3). The viral envelope has three glycoproteins: G, F, and SH protein (4). In addition, RSV has 5 other structure proteins which include L, N, P, M and M2-1 (4). Two non-structural proteins: NS1 and NS2 are identified with RSV, but it is still unknown whether these two proteins are a part of the assem...
Nguyen, Bianca. "AP Biology/BN: Bacteria vs. Virus vs. Prion." AP Biology/BN: Bacteria vs. Virus vs. Prion. N.p., 16 Dec. 2011. Web. 18 Apr. 2014. .
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.
The issue written in this article is regarding the banning and lack of approval for blight-resistant potatoes in the european union. Late potato blight, a potato disease caused by the the eukaryotic microorganism phytophthora infestans, is a significant cause for loss of crop and yield by potato farmers. Looking back to the past, the blight was responsible for the catastrophic Irish Great Famine of the 1840s causing eradication of their main food source, potatoes. As a result of the blight, potatoes become rotten and unsafe for human consumption. Late potato blight today is still a serious issue because it has caused the loss of $5.9 billion dollars of potatoes worldwide annually.By engineering blight resistance into potatoes, scientists have hoped to increase the yield and productivity of potato crops affected by this devastating disease. However, the attempts of the scientists are met with strong resistance by anti-GMO activists and lobbying groups, who are intent on food as naturally pure as possible. In consequence of not using genetically modified potatoes, the farmers are forced to use costly pesticides in an attempt to control the blight. With the human population rapidly increasing, it is essential that all measures be taken to increase food/crop yield in order to prevent starvation and hunger caused by the overpopulation. The battle between agricultural researchers like Simplot and the anti-GMO lobbying group GeneWatch is a controversial one that must be addressed by this generation and future generations.
PRSV-P can infect both Papaya and cucurbits such as watermelon and squash, while PRSV-W can only infect cucurbits. It was found that originally only type-W was present in Australia , while type P was discovered 20 years later. It is believed that PRSV-P originated as a result of mutations in PRSV-W. A Sequence analysis of both types showed that the coding sequence of the coat protein were very similar in both. (SCREENSHOT CITATION)
Viruses are the smallest, simplest living things, smaller than bacteria, and the cause of some of the deadliest diseases known to humanity. They are composed chiefly of nucleic acid wrapped in a coat of protein and are able to multiply only from within living cells. As with all other organisms, the virus depends for its ability to obtain energy and carry out the other processes necessary to sustain life, upon its stock of DNA, the hereditary material that makes up the genes, the "instructions" that determine the traits of every living organism. What is interesting about viruses, however, is that their genetic stock is very meagre indeed, so much so that reliance upon it alone cannot enable them to survive. Nonetheless, viruses do persist from one generation to the next, as if they were alive. How this is managed, as it clearly is in both plants, animals and human beings, bears importantly upon the ways in which "life", at least in the case of viruses, may legitimately b...
Most plant diseases will be destroyed. However, some heat resistant viruses will not be affected (e.g. the tobacco mosaic virus).
Using microarray gene-chip technology, we monitor RNA levels produced by 10,000 genes in both normal and mutant plants. "In the mutant plants, we found one gene, called DMI3, which produced extremely low levels of RNA. The normal version of the DMI3 gene produces a protein that is remarkably similar to tobacco plant proteins that are known to modulate their behaviors in response to calcium."
...ound in our bodies. The trick is that the virus “gets confused” and incorporates the fatal molecule into its growing RNA strands which leads to the prevention of RNA synthesis and thus the entire viral replication.
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.