Micro Ch 13

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA

During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome. During lysogeny, the viral genome is integrated into the host DNA. It is inactive at this time, and virus is not produced.

They require a host in order to reproduce.

To package and protect the viral genome

attachment

release During budding release, the virus "steals" some of the host membrane to use for itself.

The capsid breaks apart, releasing the viral genome.

Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host. Cell culture produces the most reproducible results.

Proteinaceous infectious particles

1982

Scrapie

They lack nucleic acid.

assisting in normal synaptic development and function.

Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.

Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.

The multimers are more stable and resistant to protease.

Viruses depend on host cells for replication. The herpes zoster virus is a DNA virus. It enters the host cell by attaching to host cell receptors. Once inside, the virion is uncoated to release the DNA into the nucleus of the host cell. "Early" genes, typically used for viral replication, are transcribed using the host's RNA polymerase. Viral DNA is then replicated to produce multiple copies of the DNA. The remaining components of a virion are the produced via transcription and translation of "late" genes. Capsid proteins then migrate to the nucleus of the host cell. Maturation occurs when the capsid proteins and viral DNA combine to form a complete virus. The virions are then released from the host cell to go and infect new host cells. Image C diagrams the replication of papovavirus, a DNA virus similar to herpesvirus.

her daughter and grandchildren moving into her house shortly after the death of her husband her age, 68 Many factors can contribute to reactivation of a latent virus. Research has yet to narrow it down to one thing, but stress, old age, and a change in the host's immune system have been linked to viral reactivation.

No. Because of their ages, the grandchildren have most likely been vaccinated against the chickenpox. They are also safe from contracting shingles because they are young. The grandchildren are ages 6, 8, and 12, which means that the varicella vaccine has been an available for all of them. The grandchildren are school-aged and were most likely required to receive the chickenpox vaccine before starting school. If they contracted the virus from Barbara, it would result in a mild form of the rash. This is common in previously vaccinated individuals and is called "breakthrough varicella." The grandchildren would not contract shingles from Barbara because this disease is rare in individuals younger than 20.

cold sores or fever blisters Cold sores or fever blisters are the painful, short-lived vesicles that form near the outer margins of the lips. It is transmitted via oral and respiratory routes. In the United States, a large percentage of the population is infected with this virus during infancy, when the virus is passed via respiratory droplets from family members. (Who can resist kissing a baby?)

headache fever muscle pain After the person is exposed to the flu virus, there is a short incubation period—only about one day—before symptoms of infection appear. Influenza infection commonly causes muscle aches and headache. These are most likely due to the fever that is part of the normal immune response to infection. As fever raises the body temperature, cellular demand for water will increase. At the same time, the person's appetite and thirst are typically depressed, leading to decreased consumption of water. These two factors contribute to dehydration and an electrolyte balance, which typically manifest as general malaise and headache.

After gaining entry to the host respiratory system, influenza adheres to host cells. The virus then enters the cells and begins the process of hijacking host machinery in order to produce new viral particles. After all the components are synthesized, they are assembled, and the virus leaves via budding. The newly released particles then infect neighboring cells, perpetuating the infection.

Little immunity to virus strains resulting from antigenic shift exists in the population. Viral strains resulting from antigenic shift contain RNA segments from different species. Antigenic shift results in a major change in the genetic composition of the virus. Genetic analysis of the 1918 flu revealed that it contained genetic material that was both avian and mammalian in origin. This reassortment led to a deadly combination—a virus that was both highly virulent and transmissible. These factors, coupled with the lack of immunity in any population, led to the pandemic that impacted the entire world.

increased fluid in the lungs and labored breathing an excessive inflammatory response leading to extensive tissue damage The cytokine storm during infection with the 1918 influenza was extremely destructive. The massive release of cytokines in the lungs led to an uncontrolled inflammatory response. As cells moved into the lung tissue, the tissue was destroyed. Fluid entered the lungs, and patients struggled to breathe. Furthermore, the ability to deliver oxygen to the body was severely compromised, giving many patients a blue appearance.

In order to yield a vaccine, the virus must be produced in eggs. The virus undergoes antigenic changes on a regular basis. A vaccine for influenza has been available since about 1945. The current vaccine generates protection against the three strains most likely to cause infection during the flu season. The vaccine is currently available in two forms: a nasal spray (made from live, attenuated virus) and an injection (made from inactivated virus). Although both offer protection, the effect is relatively short-lived and is specific only for the three strains contained in the vaccine.

a decrease in the release of viral particles from the cell overall decrease in the replication rate of influenza an increase in the ability of the immune system to combat the infection If taken within 30 hours of the appearance of symptoms, Tamiflu is quite effective at inhibiting viral replication. Because NA has been inhibited, the viral particles are unable to bud from the infected cells. As a result, the infection isn't perpetuated. This slowing in the replication cycle gives the body enough time to mount an effective immune response and eventually eliminate the infection.

Penetration

Assembly

Biosynthesis

The virus would not be able to infect new hosts.

latent viruses.

e

cause tumors to develop.

c

Spikes are found on some viruses. They are very consistent in structure and can be used for identification. Some enveloped viruses have spikes, and they can be used for identification, such as the H and N spikes on the influenza virus.

coronavirus Coronaviruses are not known to cause cancer. They are one cause of the common cold.

hepatitis B virus (HBV) human papillomavirus (HPV) Epstein-Barr virus (EBV)

chickenpox

papillomavirus.

measles

there are no animal reservoirs of the virus.

True

Diarrhea

headache fever chills muscle aches

annual vaccination.

young adults.

False

Antigenic shift can occur because the genome is in several pieces.

competitive inhibition

Viruses use the host cell's processes to carry out their own reproduction.