Patterns of Infections

Question 1

Natural infections can be ____ and self-limiting (____ infection) or ____ (____ infection)

Answer 1

rapid; acute; long-term; persistent

Question 2

Most latent infections begin as an ___ infection of one cell type, but when they encounter a different cell type, no ___ ____ are produced

Answer 2

acute; infectious particles

Question 3

A smoldering infection can occur in which ___ ___ ___ ___ occurs in face of a strong immune response

Answer 3

low-level viral replication

Question 4

slow infections and ____ infections are more complicated variants of persistent infections

Answer 4

transforming

Question 5

Patterns of infection can be very ____ and _____ for the virus family

Answer 5

stable; characteristic

Question 6

an acute virus runs a ___ but ___ course; hallmarks are rapid production of virion followed by _____ of infection and ____. What are some viruses that cause acute infections?

Answer 6

short; severe; elimination; clearance; rhinovirus, influenza

Question 7

Effector cells and antibodies begin to clear infected tissues after - days

Answer 7

4-5

Question 8

Incubation periods can vary from ______ to ____

Answer 8

1-2 days; years

Question 9

What is the initial period before symptoms of disease are seen? What occurs during this time? What causes the classic symptoms of an acute infection? What are these symptoms?

Answer 9

incubation period; viral replication and host response in the form of release of IFN-gamma and other cytokines; IFN-gamma and other cytokines; (Fever, malaise, aches, pains, and nausea)

Question 10

Short incubation periods generally indicate that symptoms of disease are from where?

Answer 10

The primary infection site

Question 11

Long incubation periods generally indicate that symptoms of disease are from where?

Answer 11

A secondary infection site

Question 12

For acute infections, ___ and ___ defenses limit and contain most of them. If someone is immunocompromised they can be serious and can result in? What does the healthy host depend on for immune clearance?

Answer 12

innate and intrinsic; systemic infections and damage of multiple organs; the adaptive response

Question 13

For Varicella-zoster virus (chicken pox): primary replication is in the primary lymph nodes. It takes X days before what happens?
What is the period of non-specific symptoms? How does chicken pox reach the skin?

When can they reappear and how does it happen?

Answer 13

4-6; infected t cells enter bloodstream (primary viremia);

The prodromal period

It infects skin-homing T-cells, which brings the infection to the epidermis.

Later in life, when the immune system’s function is reduced the virions travel back down from the peripheral neurons to the skin again.

Question 14

Antigenic variation: Why we get acute infections repetitively. After infection survival, the individual is immune to infections by the -__ ____. Some acute infections with ______ occur repeatedly despite robust immune response. Why?

Answer 14

same virus; rhinovirus and influenza; selection pressures lead to shedding of virions resistant to immune clearance. This is due to structural properties of virions and the capacity of neutralizing antibodies to block infectivity.

Question 15

Virus that tolerate many amino acid substitutions while remaining infectious are said to have:

Answer 15

structural plasticity

Question 16

There are over ___ different serotypes of rhinovirus maintained in humans all the time, so you may contract more than one each year. What does this mean for the possibility of a cold vaccine?

Answer 16

100; it is difficult to produce.

Question 17

Antigenic drift is what?

Answer 17

Small changes due to slight alterations of surface proteins

Question 18

Antigentic shift is what?

Answer 18

major changes in surface proteins that encodes a completely new surface protein.

Question 19

When can antigenic shift occur? What is exchanged?

Answer 19

When an organism is coinfected with two viral serotypes; virus with segmented genomes exchange blocks of genetic information; also when recombination occurs between co-replicating genomes

Question 20

Viruses with segmented genomes can exchange ____ genomes. Resulting hybrid virions may be temporarily better at what?

Answer 20

segments; evading immune defenses

Question 21

Persistent infections occur when? What is it called when a persistent infection is eventually cleared? What’s it called when it lasts the life of the host?

Answer 21

Primary infection is not cleared efficiently; chronic; latent

Question 22

Virions may be produced even in the presence of an ____ ____ ____

Answer 22

active immune response

Question 23

Sometimes ___ _____ ____ after viral proteins are no longer detected

Answer 23

viral genomes remain

Question 24

The persistent pattern is surprisingly common, especially for ___ _____ ____

Answer 24

non-cytopathic virus

Question 25

Herpesvirus have a ___ and ___ viral transcription pattern

Answer 25

latent and lytic

Question 26

When viral ____ effects and host defenses are ___ a persistent infection is likely

Answer 26

cytopathic; reduced

Question 27

A virus can reduce production of ____, reduce ___ protein expression, or inhibit ____ in order to cause a persistent infection.

Answer 27

IFN; MHC; apoptosis

Question 28

What is one of the most powerful antiviral responses?Th and cyt. T populations found after some infections are limited, the T cells respond to ____ viral peptides. These peptides are said to be ________.

Answer 28

CTL response; few; immunodominant

Question 29

properties of latent infections

Answer 29

viral gene products that promote virion production aren't made cells harboring the latent genome are poorly recognized by the immune system The viral genome persists intact and may reactivate a a later time

Question 30

How could a latent genome be maintained?

Answer 30

A non-replicating chromosome in a non-dividing cell IE neuron; may be a self-replicating chromosme in a dividing cell Could be integrated into the host chromosome

Question 31

What could replication in a mucosal epithelium form? What cell defenses limits its spread?

Answer 31

A lesion; IFN and cytokines

Question 32

sometimes all infected cells fuse together. what is this called?

Answer 32

syncytia (SP?)

Question 33

Virions released in herpes infections leave the ___ ____ of the epithelium. There it may find a ____ and switch to a ____ state

Answer 33

basal membrane; neuron; latent

Question 34

In Herpes SImplex virus (HSV), the viral genome is silenced and coated with nucleosomes (t/f) Does it need to divide?

Answer 34

T; no, because the neuron doesn't divide

Question 35

What is syncytia?

Answer 35

fusing of multiple infected cells. This causes instability

Question 36

HIV ____ CD4 T-Cell numbers and helper cell maintenance of CD8 T-cell, macrophage, and other cell functions

Answer 36

reduces

Question 37

The provirus is?

Answer 37

DNA version of retrovirus???

Question 38

HIV infects _____ _____ during sexual activity

Answer 38

mucosal surfaces

Question 39

Those with a mutation in ____ co-receptor are resistant to HIV infection

Answer 39

CCR5

Question 40

A persistent HIV infection is seen in ____, ____, _____ and hematopoietic stem cells. These serve as the ___- ____

Answer 40

macrophages, DCs, memory T cells; major reservoirs

Question 41

AIDS development correlates with increased ___ of virus and decreased ____ cells

Answer 41

release; Th

Question 42

Nef protein does what to the HIV infection

Answer 42

promotes progression of HIV infection to aids

Question 43

What is the first phase of HIV infection? What is viral concentration?

Answer 43

acute phase, 10E7 particles/mL

Question 44

During clinical latency period, HIV replication continues where?

Answer 44

lymph nodes

Question 45

What other type of immune cell decreases with an HIV infection? What does this cause?

Answer 45

CD8 cells due to lymph node distruction; immunosuppression

Question 46

what cd4 cell concentration is an indicator for onset of AIDS? What concentration is full blown AIDS?

Answer 46

350 cells/microliter; <200cells/microliter

Question 47

Activated CD4 T cells intitiate immune response by ____ ____ used for activation of other leukocytes

Answer 47

releasing cytokines

Question 48

HIV can also cause neurologic abnormalities. The ____ cell and _____ are the predominant infected cells in the brain. Why are they dangerous?

Answer 48

microglial, macrophage. They cause cellular release of neurotoxic substances or chemotactic factors that promote inflammatory response and neuronal death in the brain

Question 49

What HIV viral load involves onset of more significant diseases?

Answer 49

>75k copies/mL

Question 50

What is HIV wasting syndrome?

Answer 50

weight loss and diarrhea for >1 month

Question 51

AIDS-related dementia can result from ____ infection or HIV infection of ____ and microglial brain cells

Answer 51

opportunistic; macrophages

Question 52

HIV epidemiology: Since it's enveloped it is ____ ____ and must be transmitted via ____ ____. There is a long ______ period. Virus can be shed before development of identifiable ______.

Answer 52

easily inactivated, bodily fluids. prodromal: generalized flu-like symptoms; symptoms

Question 53

Transmission of HIV: Virus is present in ___ ___ and ____ secretions. at risk are: ____ ____ ___ ____ ; blood and organ transplant recipients, and hemophiliacs treated before ____.

Answer 53

blood, semen, vaginal secretions; IV drug abusers, sexually active people with many partners, prostitutes, newborns of HIV+ mothers; 1985

Question 54

Modes of HIV control: ____ ___ limit progression of disease, lack of ___ needles, safe sex, large scale _____ ____

Answer 54

antiviral drugs; sterile; screening programs

Question 55

in 2009, how many people have HIV, how many infections per day? how many deaths per year?

Answer 55

33.5 million; 7k, 1.8 million

Question 56

Tests for HIV infection performed for four reasons:

Answer 56

identification of those infected so antiviral drug therapy can be initiated; to identify carriers who can transmit infection; to follow course of disease and confirm diagnosis of AIDS, evaluate efficacy of treatment.

Question 57

Chronic nature of the HIV disease allows the use of ____ tests; however these cannot identify ____ ___ people

Answer 57

serologic; recently infected

Question 58

Recent HIV infection or late stage disease are identified by lots of ___ ____ in blood, ____ ___ ____ ____, or detection of ___ enzyme

Answer 58

viral RNA; p24 viral capsid antigen; RT

Question 59

What is the first step for HIV lab diagnosis? what's after that?

Answer 59

Detection of antibodiy and p24 capsid antigen; determining HIV-1 or HIV-2

Question 60

AIDS treatment: What is the Anti-HIV therapy called? What is the advantage of this?

Answer 60

Highly active antiretroviral treatment (HAART); multiple mechanisms of action reduces potential to select for resistance.

Question 61

Multidrug therapy can reduce blood levels of virus to ___ and reduce ___ and ____ in advanced AIDS patients

Answer 61

0; morbidity; mortality

Question 62

Initiation of HAART is done at Th cell levels of; alternatively it is recommended for ___ events

Answer 62

300-500; post-exposure prophylaxis (e.g. needle stick)

Question 63

What is the function of a nucleoside analog? RT inhibitor? Protease inhibitor? fusion inhibitor?

Answer 63

It inhibits viral polymerases by incorporating a terminal nucleoside; sterically disrupts RT catalytic site; prohibits protein cleavage at late stage of HIV replication cycle; blocks viral and cellular membrane fusion step involved in virus entry into cells

Question 64

Potential subunit vaccines have been unsuccessful. What were the subunits used? Why are they unsuccessful?

Answer 64

GP120, gp 160; They elicit only an antibody to a single strain of HIV and aren't successful.

Question 65

Most recent HIV vaccines do what?

Answer 65

prime T-cell responses via a different virus such as canarypox, herpesvirus, vaccinia, or defective adenovirus vector

Question 66

____ vaccine consisting of eukaryotic expression vectors (plasmid) was tried for GP160

Answer 66

DNA

Question 67

A vaccine gneerating an antibody against the CD4 binding site is under investigation and may elicit ____ ____ to most HIV strains

Answer 67

neutralizing antibody

Question 68

In a healthy host, in an acute infection _____and ____-_____ ____ are destroyed (______) by the immune system in days

Answer 68

virions and virus infected-cells; cleared

Question 69

What are the defenses available to fight off a recurring infection?

Answer 69

antibodies; residual effector cells; and memory cells

Question 70

If viral replication occurs in the presence of antibody that neutralizes virions, antibody-resistant ____ are selected for and _____. These shed virions can then reinfect whom?

Answer 70

mutants; shed; individuals who have already been exposed and have adaptive immunity towards the pre-mutated virus.

Question 71

Which viruses have little structural plasticity? What does this mean for antibody-resistant mutants?

Answer 71

Measles, poliovirus, yellow fever; they have a low probability of being selected

Question 72

How many serotypes of poliovirus are circulating? What does this mean for the vaccine?

Answer 72

3; vaccines that were effective in the 1950s are still effective today.

Question 73

What is antigenic variation?

Answer 73

It's mutation of the virus in response to antibody selection.

Question 74

How are primary infections cleared?

Answer 74

The adaptive immune response clears them through close integration with the intrinsic and innate response