During the lytic cycle of viral replication, the virus hijacks the host cell, degrades the host chromosome, and makes more viral genomes. This dormant state is known as latency, and these viruses can exist in nerve tissue for long periods without producing new viral particles, only to reactivate periodically and cause skin lesions where replication occurs. The Ebola virus is a piece of single stranded RNA, polymerase, and proteins encapsulated in a viral envelope. The West Nile Virus usually cycles around birds and several types of arthropods, but occasionally makes it out of this cycle and reaches humans. Create your account. Bacteriophages replicate only in the cytoplasm, since prokaryotic cells do not have a nucleus or organelles. For example, the varicella-zoster virus infects many cells throughout the body and causes chickenpox, characterized by a rash of blisters covering the skin. Ebola is primarily transmitted through direct contact with bodily fluids from infected patients or other species (e.g., gorillas and chimpanzees). Transduction occurs when a bacteriophage transfers bacterial DNA from one bacterium to another during sequential infections. The lysogenic cycle involves the incorporation of the viral genome into the host cell genome, infecting it from within. A temperate bacteriophage has both lytic and lysogenic cycles. Describe that process. It was later associated with Sudan and Zaire ebolavirus and resulted in more than 11,000 fatalities. In the lytic cycle, the virus attaches to the host cell and injects its DNA. Blood infusions, fluids, and electrolytes are given to patients to prevent severe blood and fluid loss. The pathogen injects its genome into the host cell's cytoplasm through a hole in the cell wall or through a hollow organelle such as flagella or pili. T-even phage is a good example of a well-characterized class of virulent phages. Attachment is the first stage in the infection process in which the phage interacts with specific bacterial surface receptors (e.g., lipopolysaccharides and OmpC protein on host surfaces). CHAPTER 4 Lesson 1 Virus - Read online for free. Want to cite, share, or modify this book? What is the difference between the lytic cycle and the lysogenic cycle - From: null <Saved by WebKit>, null <>> Date: Fri, 13 Feb 2015 06 38 42 -0600. Should such drugs be dispensed and, if so, who should receive them, in light of their extremely limited supplies? It is a one-dose shot that protects against the variant of the Ebola virus that has caused the most serious outbreak so far. What aspect of the life cycle of a virus leads to the sudden increase in the growth curve? To establish a systemic infection, the virus must enter a part of the vascular system of the plant, such as the phloem. The Ebola virus is a long, single-stranded, and filamentous negative-sense RNA virus enclosed by nucleoprotein and other viral proteins in a helical nucleocapsid. Another lytic bacteriophage is T4, which infects E. coli. Some viruses have a dsDNA genome like cellular organisms and can follow the normal flow. Ebola is a rare and deadly virus that causes a high fever, headache, and hemorrhaging. Other nearby cells can then be infected with the virus. The genus Ebolavirus consists of six species, but only four have been known to cause human disease: Zaire ebolavirus, Sudan ebolavirus, Tai Forest ebolavirus, and Bundibugyo ebolavirus. Since Ebola is often fatal, the panel reasoned that it is ethical to give the unregistered drugs and unethical to withhold them for safety concerns. What is lytic or lysogenic? Depending on the clinical care and the patient's immune system, it may vary from 25% to 90%. This, along with Duncans initial misdiagnosis, made it clear that US hospitals needed to provide additional training to medical personnel to prevent a possible Ebola outbreak in the US. Once the viral DNA has been inserted into the cell, the host is now said to be infected. The incubation period of the West Nile Virus is 2-15 days. Reproductive cycles of a bacteriophage Classify each phrase as applying to the lytic cycle, the lysogenic cycle, or both types of reproductive cycles of phages. Transduction seems to play an important role in the evolutionary process of bacteria, giving them a mechanism for asexual exchange of genetic information. It wipes out cells needed to form coagulation proteins and other essential plasma components. Lytic phages take over the host of the cell to make the phage components. EVD most commonly affects people and nonhuman primates (such as monkeys, gorillas, and chimpanzees). The lytic cycle is named for the process of lysis, which occurs when a virus has infected a cell, replicated new virus particles, and bursts through the cell membrane. lysogenic: [adjective] harboring a prophage as hereditary material. It is highly contagious and spreads from contact with an infected person's or animal's bodily fluids. Although drugs and vaccines are already used to manage severe outbreaks, their efficacies are continuously being studied. Direct Death of the Host cell. are not subject to the Creative Commons license and may not be reproduced without the prior and express written Transcription and replication The RNA replication begins with synthesizing an antigenome or the "positive-sense replicative intermediate" and the complementary strand of the RNA genome. citation tool such as, Authors: Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster. The presence of the phage may alter the phenotype of the bacterium, since it can bring in extra genes (e.g., toxin genes that can increase bacterial virulence). However, some viruses can only be transferred by a specific type of insect vector; for example, a particular virus might be transmitted by aphids but not whiteflies. Researchers working with Ebola virus use layers of defenses against accidental infection, including protective clothing, breathing systems, and negative air-pressure cabinets for bench work. Retroviruses are a type of virus that use a special enzyme called reverse transcriptase to translate its genetic information into DNA. It is typical of temperate phages to be latent or inactive within the cell. Phages that replicate only via the lytic cycle are known as virulent phages while phages that replicate using both lytic and lysogenic cycles are known as temperate phages. Depending on the type of nucleic acid, cellular components are used to replicate the viral genome and synthesize viral proteins for assembly of new virions. Figure 6.2. It also aids in the viral assembly during the replication stage. Rochelle has a bachelor's degree in Physics for Teachers from Philippine Normal University-Manila and has completed 30+ units in MS Geology at University of the Philippines-Diliman. Lytic animal viruses follow similar infection stages to bacteriophages: attachment, penetration, biosynthesis, maturation, and release (see Figure 6.10). References. 32 pages. In the last stage of infection, the bacterium lyses and releases the viruses that were produced inside the cell. Attachment It attaches itself to a receptor on the host cell membrane using glycoprotein. Establishment is not well-understood in herpesviruses. The RdRP is brought in by the virus and can be used to make +ssRNA from the original ssRNA genome. copyright 2003-2023 Homework.Study.com. This unique recognition can be exploited for targeted treatment of bacterial infection by phage therapy or for phage typing to identify unique bacterial subspecies or strains. Ebola virus is one of the species within the genus Ebolavirus and family Filoviridae, characterized by the long, single-stranded, and filamentous negative-sense RNA (ribonucleic acid) viruses. Scribd is the world's largest social reading and publishing site. typically use the cell's machinery to make as many virions as and you must attribute OpenStax. During this time, the virus does not kill the nerve cells or continue replicating. What is lytic or lysogenic? As it assembles and packages DNA into the . This corresponds, in part, to the eclipse period in the growth of the virus population. If a virus has a +ssRNA genome, it can be translated directly to make viral proteins. Once the virus is inside the cell, other processes such as uncoating, fusion, transcription, replication, and assembly occur with the aid of several proteins. initial infection The varicella-zoster virus is transmitted through the virions on the infected person's skin. This situation is an example of compassionate use outside the well-established system of regulation and governance of therapies. Uncoating and fusion The viral membrane fuses with the host cell's vesicle membrane, and the nucleocapsid is released into the cell's cytoplasm. The provirus stage is similar to the prophage stage in a bacterial infection during the lysogenic cycle. Ebola, or the Ebola hemorrhagic fever, is a viral disease that affects humans and other primates. (b) After a period of latency, the virus can reactivate in the form of shingles, usually manifesting as a painful, localized rash on one side of the body. 8. Release Viral particles start to "bud off", where the plasma membrane wraps them until they protrude and pinch off from the cell surface. After induction has occurred the temperate phage can proceed through a lytic cycle and then undergo lysogeny in a newly infected cell (see Figure 6.8). A vaccine for Ebola was approved by the Food and Drug Administration in December 2019. In lysogenic cycles, the spread of the viral DNA occurs through normal reproduction of the host, whereas in lytic cycles, many copies of the virus are created quickly and the host cell is destroyed. Ebola is a lytic virus - it reproduces due to the lytic cycle. Only a minority of plant viruses have other types of genomes. The Lytic Cycle Virus Reproduction The Lysogenic Cycle Do not destroy the host cell at first. A lysogenic virus does not act on bacteria as a lytic virus does. Once the Ebola virus enters the cell, unknown factors trigger the uncoating of the nucleocapsids enveloping the viral RNA. Dec 20, 2022 OpenStax. Some examples of lysogenic cycles in bacteria include Corynebacterium diphtheriae, Vibrio cholerae, and Clostridium botulinum. An increased frequency of Guillain-Barr syndrome has been reported in areas with active Zika infections, but researchers are still investigating whether there is a causal connection ^ {20} 20. Plant viruses may be enveloped or non-enveloped. During this type of viral reproduction, the viral DNA integrates into the host cell DNA. In August 2014, two infected US aid workers and a Spanish priest were treated with ZMapp, an unregistered drug that had been tested in monkeys but not in humans. During the eclipse phase, Duncan would have been unable to transmit the disease to others. Includes examples of lytic and lysogenic viruses - measles, rabies, and more. The RNA contains the instructions for replicating and assembling new viral particles. What is Ebola? Second, the lysogenic cycle merges the virus's genome with the host cell's genome, which is not possible for RNA viruses unless they are retroviruses. After binding to host receptors, animal viruses enter through endocytosis (engulfment by the host cell) or through membrane fusion (viral envelope with the host cell membrane). Public health officials were able to track down 10 high-risk individuals (family members of Duncan) and 50 low-risk individuals to monitor them for signs of infection. Shigella dysenteriae, which produces dysentery toxins from the genes of lambdoid prophages, Streptococcus pyogenes, which produces a pyrogenic exotoxin through lysogenic conversion and causes scarlet fever, and c. As the phloem as a lytic virus - it reproduces due to the lytic,. Replication stage viruses have other types of genomes to play an important in... Is 2-15 days important role in the lytic cycle viral genome into the host cell,... 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