Term
| where can viral diseases only reproduce? |
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Definition
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Term
| what do viral diseases consist of? |
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Definition
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Term
true or false
viruses lack metabolic enzymes like ribosomes and shit? |
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Definition
| true dat, they use host cell machinery thats why they can only reproduce inside the host |
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Term
| in the interest of the virus not to cause death of its host what does a virus need to be able to do? |
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Definition
| have a long latency period OR have easy transmission |
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Term
| who can the influenza virus affect? |
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Definition
| humans, birds, pigs, horses, seals |
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Term
| which part of the body does influenza virus affect? |
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Definition
| upper respiratory tract and major central airways |
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Term
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Definition
| Worldwide epidemics - new strains and little immunity |
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Term
| swine flu is known as H1N1 strain. When did this strain previously occur in history and what was it called? |
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Definition
occured in 1918 and it was called the spanish flu
(20-50 million people dead) |
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Term
| 1957-58. which strain of flu was this and what was it called? |
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Definition
| H2N2 and it was called Asian flu |
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Term
| 1968-69 which influenza strain occured? |
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Definition
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Term
| 2009 which strain of influenza re-emerged? |
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Definition
|
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Term
| which subtype of influenza causes pandemics? |
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Definition
|
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Term
| which subtypes of influenza affects humas only? |
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Definition
|
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Term
| which influenza subtype is a mild human illness? |
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Definition
|
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Term
| what shape and diameter is the influenza? |
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Definition
|
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Term
| what kind of genome does the influenza virus contain |
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Definition
|
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Term
| how many strands of ssRNA does the influenza virus contain? |
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Definition
|
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Term
| what does the H and the N stand for in H1N1? |
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Definition
HA =Heamagluttinin
NA = Neuraminidase
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Term
| the outer envelope of influenza is made form Lipid bilayer. where is this derived from? |
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Definition
| the plasmamembrane of the infected host cell |
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Term
|
Definition
| Sialic Acid in the upper respiratory tract |
|
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Term
| how many types of heamagluttinin are there in type A influenza? |
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Definition
|
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Term
| how many types of NA (neuraminidase) are there in type A influenza? |
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Definition
|
|
Term
| what does neuraminidase help to do? |
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Definition
| helps viral budding from host cell |
|
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Term
| what does the nucleocapsid of the influenza virus contain? |
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Definition
| 8 different single strands of RNA (ssRNA) + protein + RNA polymerase |
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Term
| influenza genome replicates inside the host for 2 functions what are they? |
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Definition
| one template of rna is used to make mRNA which orders the synthesis of glycoproteins and capsid proteins and another strand of RNA is used to make more copy of genome (ssRNA) |
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Term
| what happens when the influenza virus approaches a host cell? |
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Definition
| HA from virus binds to Sialic acid and host cell and capsid + genome enter the cell |
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Term
| what are natural killer cells? |
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Definition
| they are a type of white blood cells involved in the NON-SPECIFIC killing of virus infected cells. they do not attact to epitopes or anything like that |
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Term
| which part of the immune response are natural killer cells associated with? |
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Definition
| the innate immune response |
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Term
| innate immune response involves the induction of interferons. what are they? |
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Definition
| they are chemicals made by infected cells and macrophages and lead to degradation of viral RNA eg, IFN-alpha; IFN-beta |
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Term
| what are the 2 responses to viral infection? |
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Definition
|
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Term
| in aquired immunity what do B cells protect against? |
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Definition
| pathogens and toxins in extra celluar fluid |
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Term
| in aquired immunity what do tc cells defend against? |
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Definition
| infected cells, cancer cells and transplanted cells |
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Term
| in the influenza virus how are new infectious strains made? |
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Definition
| constant alterations of HA and NA |
|
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Term
| what is the main antigenic feature of influenza? |
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Definition
|
|
Term
| what is the function of the binding cleft? |
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Definition
| bind sialic acid on host cell |
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|
Term
characteristics of antigenic DRIFT (4)
|
|
Definition
- minor changes in protein structure
- Epidemics
- cause: lack of viral rna polymerase proofreading. Point mutations
- occurs in influenza A,B and C
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|
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Term
|
Definition
- the sudden emergence of a new antigenic subtype
- HA/NA are very altered.
- Only happens in Influenza A
- causes pandemics
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|
|
Term
| what causes antigenic Shift? |
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Definition
| 2 different strains of (human/animal) influenza infect the same cell. RNA from each exposed and mixed up. eg. H3N2 and H5N1 infect cell. cell could produce new H3N1. No immunity. |
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Term
|
Definition
|
|
Term
| what are symptoms associated with HIV? |
|
Definition
Pneumonia
Kaposi's sarcoma
Reduced levels of CD4+ Helper T cells |
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|
Term
| what is the clinical term for the final stage manifestations of HIV infection? |
|
Definition
|
|
Term
|
Definition
Seroconversion - presence of antibodies to HIV (present within a few months, usually 3)
RNA testing - looking for viral dna itself. blood test and takes shorter than seroconversion but less commonly used.
reduced cd4 t-cell count |
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Term
| with a CD4 T helper cell count at less than 200 p/ul what would it be a strong indication of? |
|
Definition
AIDS
normal ranfe approximatley 500-1100 /ul |
|
|
Term
| what type of virus is HIV? |
|
Definition
|
|
Term
| name 3 enzymes present in HIV virion |
|
Definition
protease
intergrase
reverse transcriptase |
|
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Term
| how many receptors does HIV have? what are their names and positions? |
|
Definition
there are 2 receptors
they form an ice cream cone and icecream.
the gp41 is the icecream cone (bottom)
the gp120 is the icecream on top |
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Term
| what is needed for the hiv virus to attach to the host cell? |
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Definition
| its receptors gp120 and gp41..also needs CCR5/CXCR4 on host cell in order to enter cell. |
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Term
| how many strands of genetic information contain in HIV? |
|
Definition
|
|
Term
t of false
HIV has a long latency period? |
|
Definition
| true and after this long latency period it can undergo rapid mutation |
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|
Term
| hiv is a retrovirus what does this mean? |
|
Definition
| it uses reverse transcriptase to synthesis double stranded DNA |
|
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Term
| what happens if a cell have no co receptor like CCR5 or CXCR4? |
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Definition
| then HIV cannot enter the cell. this is a requirement for the virus to penetrate the cell |
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Term
| what happens to the RNA template after dsDNA has been synthesised? |
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Definition
|
|
Term
| in HIV for the dsDNA to be intergrated into the host genome which enzyme is needed? |
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Definition
|
|
Term
| what is the dsDNA used to make? |
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Definition
| more of ssRNA for the virus that will bud off and infect other cells. |
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Term
| in the acute phase of hiv infection there are high levels of virus in your blood. this causes a ...... in CD4 T helper cells |
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Definition
|
|
Term
| is the number of CD4 Thelper cells recovered? |
|
Definition
| yes as antibodies to virus are generated the Tc cells kill infected cells and CD4 T helper cells are recovered. |
|
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Term
| what happens to the level of HIV in the blood in chronic phase? |
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Definition
| HIV levels have fallen in the blood BUT continue to be made in the lymph nodes. |
|
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Term
| what does the continous reproduction of HIV in lymph nodes do? |
|
Definition
| causes damge to lymphatic tissue. |
|
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Term
| why does the depletion of CD4 T helper cells lead to extensive loss of humoral and cell mediated response? |
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Definition
| T helper cells are needed to fully activate B cells and Tc cells. |
|
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Term
| why can the immune system not win HIV? (4) |
|
Definition
- high mutation rate as reverse transcriptase cannot proofread
- Helper T Cell depleted (needed for humoral and cell mediated response)
- breakdown of lymphatic tissue
- proviral form can hide from the immune system
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|
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Term
| treatments like AZT can inhibit proviral cDNA formation. But like bacteria and antibiotics what happens? |
|
Definition
| resistant viral forms are produced |
|
|
Term
| how does a rescriptor work? |
|
Definition
| by inhibiting the reverse transcriptase enzyme |
|
|
Term
| how does indinavir and crixidan work? |
|
Definition
| they inhibit viral protease |
|
|
Term
| other ways HIV therapeutics work are by inhibiting intergrase needed to incorporate the DNA into host genome and? |
|
Definition
| inhibiting fusion of virus and cell |
|
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Term
|
Definition
combination therapy -
highly active anti retroviral therapy |
|
|
Term
| why cant a vaccine be developed? |
|
Definition
- most vaccines prevent disease, not infection
- would a live-attenuated virus of HIV be safe?
- genital tract route of infection is unusual - will a vaccine work?
- testing on animals/primates ethical issues
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