The high degree of mutation in HIV, the accumulation of variant viruses, and the development of resistance to drug regimes are attributed to _____. a. antigenic shift b. gene conversion c. absence of proofreading capability of reverse transcriptase d. antigenic variation of variable surface glycoproteins (VSGs) e. mutation of HIV RNA genome by host-cell RNA polymerase.

The high degree of mutation in HIV, the accumulation of variant viruses, and the development of resistance to drug regimes are attributed to _____. a. antigenic shift b. gene conversion c. absence of proofreading capability of reverse transcriptase d. antigenic variation of variable surface glycoproteins (VSGs) e. mutation of HIV RNA genome by host-cell RNA polymerase.

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter12: Body Defenses

Section: Chapter Questions

Problem 2TAHL

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Antigenic shifts in influenza viruses are represented by dra-matic changes in the viral antigens. It is likely they arise fromrare events in which:(a) Two different influenza viruses infect a cell at the sametime(b) Two separate viruses undergo lysogenic conversion(c) Two viruses conjugate(d) Mutations accumulate(e) All of the above
Antigenic drift refers to: A.The reassortment of genomic segments from different viruses B.Cytotoxic T cells identifying viral infected host cells C.The accumulation of mutations in the viral genome due to an error prone polymerase D.Antigen presenting cells failure to recognize the influenza virus
Let’s say there are two closely related viruses, let’s call them Guernsey virus and Micro virus. These two viruses only infect epithelial cells. Their surface antigens are sufficiently similar that there are a number of shared epitopes between the two viruses. Choose one of the following: A) If you get infected and successfully recover from one virus, it’s quite possible that you’ll have neutralizing antibodies against the other. B) If you get infected and successfully recover from one virus, you’ll still be susceptible to the other one because the antigens aren’t exactly the same. C) If you get infected and successfully recover from one virus, it’s likely that getting infected with the other virus will be worse because of the common phenomena of antibody-dependent enhancement. D) Not enough information has been given.
Notice the dotted line for a CD4 count of 200. Why is that level important? A This is the point at which ART should begin. B CD4s of 200 represent the point at which HIV will begin to generate resistance mutations. C When CD4s reach 200, a person is at great risk of disease from opportunistic infections, including ones that hardly ever cause disease in people with normal CD4s.
Identify the statement that does not provide accurate evidence as to why HIV is so lethal. a. During the course of infection, HIV increases immune activation by altering intestinal physiology to let more microbes into the blood supply. b. Immune evasion increases in many infections due to HIV virions evolving new and unrecognizable epitopes (antigens). c. In many individuals the virus population evolves to use different receptors to gain access to a greater diversity of host immune cells. d. HIV causes enhanced replication and proliferation of T cells, which allows the immune system to work better at defending against pathogens.
Which of the following is the most likely explanation for an individual who lacks CCR5 as a result of a homozygous defect in the CCR5 gene becoming infected with HIV? a. The mutated CCR5 genes reverted to the normal form, rendering macrophages susceptible to macrophagetropic HIV variants. b. The macrophage-tropic HIV variant entered host cells using CD4 alone. c. The viral nucleic acid alone was taken up by cells, as in cell transformation by bacterial DNA. d. The individual had received a transplant of HIV-infected cells expressing normal CCR5. e. The primary infection involved a lymphocyte-tropic strain of HIV that used CXCR4 as its co-receptor.
_____ describes the situation when the immune response generated against an influenza strain limits future antibody responses to variant epitopes of a different, but similar, strain. a. Attenuation b. Herd immunity c. Variolation d. Neutralization e. Original antigenic sin.
a cytokint storm is an overproduction of immune cells and their activating compounds- cytokines can be caused by? a. flu viruses and covid-19 b. covid-19 only c. flu viruses only d. all choices are correct e. a coontagious bacterial disease only
Which one of the following most correctly describes vaccines containing live, attenuated pathogens? A.They are administered by injection. B.They provide little cell-mediated immunity. C.There is no possibility for reversion to pathogenic form. D.Pathogen does not multiply in human hosts E.They provide extended, sometimes life-long immunity.
e) Bats have been implicated as the source of many viruses against which humans have a difficult time mounting an effective immune response. Interestingly, flight plays an important role. i) Describe and explain i) the role that flight plays in creating these kinds of viruses, ii) how the viruses cross over into humans, and iii) why our immune response has a more difficult time mounting an effective response against them
A vaccine that employs a toxoid is based upon a ______. A) antibody B) attenuated virus C) histamine D) inactivated form of a bacterial exotoxin
An epitope associates with which part of an antigen receptoror antibody?(A) the tail(B) the heavy-chain constant regions only(C) variable regions of a heavy chain and light chaincombined(D) the light-chain constant regions only