Mononucleosis And HIV Retrovirus
.JPG "Mononucleosis And HIV Retrovirus - Quiz")
Mononucleosis, often referred to simply as “mono”, and the human immunodeficiency virus are both up for discussion in the following quiz, as we look at the two viral conditions which are most commonly known to be contracted via intimate acts such as kissing and intercourse. What can you tell us?
- 1.
A 17-year old woman presents with a sore throat, fever and fatigue. A rapid serologic test revealed the presence of heterophile antibodies. Which cells are infected and which may become transformed?
- A.
Lymph node dendritic cells and T cells, respectively
- B.
Oropharyngeal cells and B cells, resp.
- C.
Monocytes and hepatocytes, resp.
- D.
T cells and macrophages
- E.
Skin cells and Downey Type cells
Correct Answer
B. Oropharyngeal cells and B cells, resp.Explanation
In this scenario, the presence of heterophile antibodies indicates that the woman is likely suffering from infectious mononucleosis, which is caused by the Epstein-Barr virus (EBV). EBV primarily infects oropharyngeal cells, leading to symptoms such as sore throat, fever, and fatigue. Additionally, B cells can become transformed by the virus, leading to their proliferation and the characteristic atypical lymphocytes seen in the blood. Therefore, the correct answer is oropharyngeal cells and B cells.Rate this question:
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- 2.
………..continuation: A 17-year old woman presents with a sore throat, fever and fatigue. A rapid serologic test revealed the presence of heterophile antibodies Confirmation of the woman’s diagnosis can be made by detection of antibodies against which of the following?
- A.
Sheep and horse erythrocytes
- B.
Peptidoglycan
- C.
DNA
- D.
Parvovirus B19
- E.
None of the above
Correct Answer
A. Sheep and horse erythrocytesExplanation
The presence of heterophile antibodies in the woman's serologic test suggests that she may have infectious mononucleosis, which is commonly caused by the Epstein-Barr virus (EBV). The antibodies produced in response to EBV can agglutinate sheep and horse erythrocytes, which can be detected through a test called the Monospot test. Therefore, detection of antibodies against sheep and horse erythrocytes can confirm the diagnosis of infectious mononucleosis. Peptidoglycan, DNA, and Parvovirus B19 are not specific markers for infectious mononucleosis, so they are not used to confirm the diagnosis.Rate this question:
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- 3.
………..continuation: A 17-year old woman presents with a sore throat, fever and fatigue. A rapid serologic test performed revealed the presence of heterophile antibodies, indicative of a viral infection. Which of the following is the pathogen?
- A.
Herpesvirus
- B.
Adenovirus
- C.
Measles virus
- D.
Parvovirus B19
- E.
None of the above
Correct Answer
A. HerpesvirusExplanation
The correct answer is Herpesvirus. The presence of heterophile antibodies is indicative of infectious mononucleosis, which is commonly caused by the Epstein-Barr virus (EBV), a member of the Herpesvirus family. Therefore, Herpesvirus is the most likely pathogen in this case. Adenovirus, Measles virus, and Parvovirus B19 are not typically associated with heterophile antibody production in infectious mononucleosis.Rate this question:
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- 4.
Which of the following tumors is caused by a herpesvirus that uses the C3d complement receptor?
- A.
Leyomyoma
- B.
Hodgkin’s Lymphoma
- C.
Chondrosarcoma
- D.
Osteosarcoma
- E.
T cell lymphotropic lymphoma
Correct Answer
B. Hodgkin’s LymphomaExplanation
Hodgkin's lymphoma is caused by a herpesvirus that uses the C3d complement receptor. This receptor is involved in the immune response and helps the virus evade the immune system. Other tumors listed, such as leomyoma, chondrosarcoma, osteosarcoma, and T cell lymphotropic lymphoma, are not associated with this specific herpesvirus or the C3d complement receptor.Rate this question:
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- 5.
The cellular response typical of infectious mononucleosis caused by Epstein-Barr virus is due to:
- A.
Production of homophile antibodies
- B.
Agglutination with T cells
- C.
Proliferation of T cells
- D.
Macrophages responding to dead epithelial cells
- E.
None of the above
Correct Answer
C. Proliferation of T cellsExplanation
The cellular response typical of infectious mononucleosis caused by Epstein-Barr virus is due to the proliferation of T cells. This viral infection leads to the activation and expansion of T cells, particularly CD8+ cytotoxic T cells, which play a crucial role in controlling the infection. The increased proliferation of T cells is responsible for the characteristic symptoms of infectious mononucleosis, such as swollen lymph nodes, sore throat, and fatigue.Rate this question:
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- 6.
An 18-year old woman presents with mild pharyngitis without exudate. She claims to have fever and fatigue. No heterophile antibodies were detected. Which of the following is most likely the causative agent?
- A.
Human simplex virus type 1
- B.
Cytomegalovirus
- C.
Epstein-Barr virus
- D.
Epstein-Barr virus
- E.
Non of the above
Correct Answer
B. CytomegalovirusExplanation
The most likely causative agent in this case is the Epstein-Barr virus. This is because the patient is presenting with pharyngitis, fever, and fatigue, which are common symptoms of Epstein-Barr virus infection. Additionally, the absence of heterophile antibodies suggests that the patient does not have infectious mononucleosis, which is typically caused by the Epstein-Barr virus. Therefore, the correct answer is Epstein-Barr virus.Rate this question:
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- 7.
What conclusions would you draw from the following HIV-1 ELISA test? HIV-1 p24 ELISA
- A.
All 3 patients are seropositive
- B.
All 3 patients are seronegative
- C.
Only patient 1 is seropositive
- D.
Only patient 2 is seropositive
- E.
Only patient 3 is seropositive
- F.
Patients 1 and 2 are seropositive
- G.
Patients 1 and 3 are seropositive
- H.
Patients 2 and 3 are seropositive
Correct Answer
G. Patients 1 and 3 are seropositiveExplanation
The conclusion drawn from the given HIV-1 ELISA test is that patients 1 and 3 are seropositive. This means that they have antibodies against HIV-1 in their blood, indicating that they have been infected with the virus. The test results for patients 2 and the other patients are not mentioned, so it cannot be determined whether they are seropositive or seronegative.Rate this question:
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- 8.
Knowing that HIV-1 primarily infects leukocytes, which of the following individuals, if any, is more likely to contract HIV-1?
- A.
An otherwise healthy individual who has a sexual intercourse with an HIV-1-infected person
- B.
An individual suffering from a cold who has a sexual intercourse with an HIV-1-infected person
- C.
An individual suffering from a genital herpes flare-up who has a sexual intercourse with an HIV-1-infected person
- D.
An otherwise healthy intravenous drug user who has a sexual intercourse with an HIV-1-infected person
- E.
All previous individuals are equally likely to contract HIV-1
Correct Answer
C. An individual suffering from a genital herpes flare-up who has a sexual intercourse with an HIV-1-infected personExplanation
An individual suffering from a genital herpes flare-up is more likely to contract HIV-1 because the presence of genital herpes increases the risk of HIV transmission. Genital herpes causes open sores or ulcers, which provide an entry point for the HIV virus. The combination of genital herpes and HIV-1 infection can lead to a higher viral load and increased transmission rates. Therefore, this individual is at a higher risk compared to the other options mentioned.Rate this question:
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- 9.
And why?
- A.
Because the immune system of the healthy individual is not activated, making this individual more at risk of contracting HIV-1
- B.
Because the individual suffering from a cold is likely to exhibit a strong immune response, therefore offering more cellular targets (leucocytes) to the virus and putting this individual more at risk of contracting HIV-1
- C.
Because the individual suffering from genital herpes is likely to exhibit a localized immune response conducive to the spread of the virus and putting this individual more at risk of contracting HIV-1
- D.
Because the otherwise healthy intravenous drug user has a depressed immune system, making this individual more at risk of contracting HIV-1
- E.
This answer seems so alien to us that, surely, it has to be right…
Correct Answer
C. Because the individual suffering from genital herpes is likely to exhibit a localized immune response conducive to the spread of the virus and putting this individual more at risk of contracting HIV-1Explanation
Genital herpes is a sexually transmitted infection that causes sores and blisters in the genital area. When a person has an active outbreak of genital herpes, their immune system responds by sending immune cells to the affected area to fight off the infection. However, this immune response can create an environment that is more favorable for the transmission of other infections, including HIV-1. The presence of genital herpes can cause breaks in the skin or mucous membranes, which can provide an entry point for the HIV virus. Therefore, individuals with genital herpes are at a higher risk of contracting HIV-1.Rate this question:
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- 10.
Presented in the following figure is the natural progression of an HIV infection. Which event is marks a critical turning point in the pathogenesis of AIDS?
- A.
Emergence of CCR5-tropic virus strain
- B.
Emergence of CXCR4-tropic virus strain
- C.
Emergence of CD8-tropic virus strain
- D.
Emergence of CD4-tropic virus strain
- E.
Emergence of macrophage-tropic virus strain
Correct Answer
B. Emergence of CXCR4-tropic virus strainExplanation
The emergence of CXCR4-tropic virus strain marks a critical turning point in the pathogenesis of AIDS because it signifies a shift from the initial CCR5-tropic virus strain to a more aggressive and destructive strain. CXCR4-tropic strains have a higher affinity for CD4 cells, which are crucial for immune function. This shift in viral tropism leads to a rapid decline in CD4 cells and a weakened immune system, ultimately resulting in the development of AIDS.Rate this question:
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- 11.
HIV carries the templates required for the production of a number of essential proteins. Specifically the env gene encodes gp 120 and gp 41. Which of the following correctly describe function of the two glycoproteins?
- A.
Gp 120 binds to chemokine receptors CCR5 and CXCR4, while gp41 binds to CD4
- B.
Gp 120 is used for fusion, while gp 41 binds to CD4
- C.
Gp 120 binds to CD4 and gp 41 binds to chemokine receptors CCR5 and CXCR4
- D.
Gp 120 binds to CD4 and gp41 is used for fusion
Correct Answer
D. Gp 120 binds to CD4 and gp41 is used for fusionExplanation
(fusion 41)
BINDING:
The replicative cycle begins when gp120 binds CD4+. Binding of gp120 with CD4+ induces a conformational change in CD4+, allowing CD4+ to recruit a chemokine receptor (co-receptor; CCR5 initially & CXCR4 in later stages of the infection) in the vicinity of gp120, as well as bringing the viral
envelope closer to the cell membrane.
The gp120-CD4+-chemokine receptor complex then induces a conformational change in gp120, therefore exposing the fusion peptide gp41 (TM).
Fusion:
The exposition of gp41 leads to yet another conformational change (in gp41 this time), thereby initiating membrane fusion. In essence, gp41 is a coiled-coil structure that springs out and basically harpoons the cell membrane via the N-terminus hydrophobic region of the protein to initiate fusion. The fusion protein then folds back into a hairpin structure, bringing the membranes closer together. The stress induced on the lipid bilayers likely leads to the formation of a hemi-fusion stalk, followed by the formation of the fusion pore through which the nucleocapsid enters the cell.Rate this question:
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- 12.
After infection with HIV, there is an initial increase in patient viral load, followed by marked, but not permanent, decrease in viral load. If you were to examine the patients lymphocyte populations during this period of viral load decrease, what would you expect to find?
- A.
Lowered CD4+ and CD8+ T cells; CD4/CD8 ratio greater than 1
- B.
Raised CD4+ and CD8 + T cells; CD4/CD8 ratio greater than 1
- C.
CD4+ T cells within the normal range, CD8+ T cells raised; CD4/CD8 ratio less than 1
- D.
Lowered CD4+, raised CD8+ T cells; CD4/CD8 ratio less than 1
Correct Answer
D. Lowered CD4+, raised CD8+ T cells; CD4/CD8 ratio less than 1Explanation
The disease process in untreated HIV-infected individuals occurs in three stages: The acute phase, the chronic (or asymptomatic) phase and the AIDS (or end-stage, also referred to as the symptomatic phase). During the acute phase, initial infection with HIV results in viral dissemination to the lymphoid tissue and numerous other sites. During this phase, viremia (number of viruses found in blood, also referred to as the viral load) peaks and then drops when the CD8+ CTL response is initiated (HIV-specific CTLs; TH1 response). This response takes a couple of weeks to a month to arise. During this phase, the observed depletion of CD4+ T-lymphocytes in peripheral blood (CD4+ cell count) is not only due to the cytopathic effects of viral infection (direct viral cytopathic effects), but also to the destruction of infected CD4+ cells by CD8+ cytotoxic T-lymphocytes, as well as sequestration of high numbers of both CD4+ and CD8+ cells in lymphoid tissues (which explains the lymphadenopathy associated with HIV primo-infection). After another few weeks, an efficient neutralizing antibody response develops. Consequently, the viral load decreases and the CD4+ counts increase again. This phase induces a febrile illness (mononucleosis-like syndrome) that lasts 3 to 4 months, and is characterized by fever, malaise, pharyngitis, lymphadenopathy, headache, arthralgias, diarrhea, maculopapular rash, and meningoencephalitis. However, partly due to poor reverse transcriptase proofreading activity, escape mutants to CTLs and neutralizing antibodies rapidly arise (refer to the section on escape mutants in the HTLV-1 part) and the infection slides into the chronic phase. Although this phase, which can last years, is asymptomatic, it is characterized by a steady-state level of HIV replication as well as a slow and steady decline in circulating CD4+ cells, potentially driven by viral reservoirs such as memory lymphocytes and macrophages. The end-stage phase (full-blown AIDS) lasts months to years, and is characterized by the appearance of severe, signature (AIDS-defining) opportunistic diseases such as Candida albicans, Pneumocystis jirovecii, Cryptococcus neoformans, Mycobacterium avium, Toxoplasma gondii, or Isospora belli infections among others, reactivation of herpesviruses such as VZV, EBV and HCMV, as well as malignancies such as Kaposi’s sarcoma, before death ultimately occurs.Rate this question:
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- 13.
In the course of an HIV-1 prevalence study in a high risk group, for which you are the principal investigator, a week’s worth of sera is screened in the laboratory by ELISA. Serum samples yielding a positive result are then re-tested by western blot analysis for confirmation. The following results are obtained: Which samples are indicative of HIV-1 infection?
- A.
I, II, IV, and V
- B.
II, IV, and V
- C.
I, II, III, and V
- D.
I, II, III, IV, and V
- E.
V
Correct Answer
D. I, II, III, IV, and VExplanation
Interpretation:
– Negative result: Total absence
of bands associated with HIV-1
(CDC guidelines); According to
the WHO guidelines, a very weak
p17 band would also qualify as a
negative result
– Positive result: Presence of at
least 2 of the following bands
(CDC guidelines):
• p24
• gp41
• gp120/160Rate this question:
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.JPG "Presented in the following figure is the natural progression of an HIV infection.
Which event is marks a critical turning point in the pathogenesis of AIDS?")
.JPG "In the course of an HIV-1 prevalence study in a high risk group, for which you are the principal investigator, a week’s worth of sera is screened in the laboratory by ELISA. Serum samples yielding a positive result are then re-tested by western blot analysis for confirmation. The following results are obtained:
Which samples are indicative of HIV-1 infection?")
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