Joy Lowe
Microorganism Profile Assignment
February 10, 2019
1. Description of the Microorganism:
Human Immunodeficiency Virus (HIV) is a highly complex RNA virus of the genus Lentivirus within the Retroviridae family. The virus is spherical that contains a core that contains two strands of genomic RNA and is surrounded by a lipid envelope. The lipid envelope is derived from the host plasma membrane. HIV-2 is less prevalent and less pathogenic type and is found primarily in western Africa, (Engelkirk, 2015). HIV, is the virus that causes AIDS (Acquired Immunodeficiency Syndrome) and can be transmitted during sexual intercourse; while sharing syringes; or from mother to child during pregnancy, childbirth or breastfeeding. This virus was t identified in 1981, HIV is the cause of one of humanity’s deadliest and most persistent epidemics, (DHHR, 2018).
The main focus of this paper will be on HIV – 1. The tests used to confirm diagnosis are:
· the ELISA (enzyme-linked immunosorbent assay) test; blood sample is taken and the serum are put on a plate containing antigens for HIV. If the patient is infected with HIV, his blood will contain antibodies that will attach to the antigens on the plate. The sample is then washed with a solution that will wash other particles away isolating the antigen with the patient’s antibodies attached to it. This is treated with an enzyme that attaches to the antibodies of the antigens and a chemical reaction takes place which results in color change. This color change shows a positive result of HIV this is visualized using a transmission electron microscope.
· If ELISA test is positive, then a Western blot test is performed. To perform this test, you separate your proteins on a gel, and then you detect your protein with an antibody and a second antibody coupled to an enzyme. It's less sensitive than ELISA but you see that your detection is specific because you see only one band.
· You can also determine if someone is infected with HIV by using an immunofluorescence microscopy. This is used to localize the protein inside the cell by use of fluorophores to visualize the location of bound antibodies.
· The HIV-1 core antigen (p24) test detects circulating viral antigen which may be found prior to the development of antibodies; this test is done with an Electron microscope, (Quest, 2016).
· Saliva tests (home kits) This test will detect HIV antibodies but it is HIV antibodies don't accumulate in saliva at the same speed or levels as in blood. Positive results are confirmed with a blood tes,t (Parker, Schneegurt, Thi Tu, Forster, & Lister, Microbiology, 2018).
2. Virulence Factors: How do they affect the host?
The virus is transmitted to a person through sexual contact, the sharing of needles with an infected individual, from mother to baby during birth or through breast milk. Once a patient is infected, the virus will soon encounter its target cells; which are T cells, macrophages and dendritic cells. When the HIV virus invades the host (cell), it begins to replicate by transcribing its RNA into the DNA of the host cell, the cell will then translate and transcribe the virus. The virus will begin to replicate, by attacking the CD4 cells (helper T cells). Once the CD4 cell is infected, it goes through the blood stream infecting other helper T cells thereby weakening the immune system making the patient susceptible to infections that they body would normally have been able to fight off, (Parker, Schneegurt, Thi Tu, Forster, & Lister, Microbiology, 2018). The CD8+ T-cells help to stop viral infections by recognizing infected cells and creating memory cells for immunity purposes. The HIV virus has developed ways to evade the CD8+ T-cell response, (Gulzar N., Copeland, KF.,2004).
I have learned during this quarter of Microbiology that a virus will go inside of a cell to replicate making it more difficult for the body to kill it. I learned that the virus has spikes that protrude from its envelope that help it attach to the host cell. The viral adhesion on the spike is the glycoprotein gp20. The envelope of the HIV virus is actually part of the cell membrane that was stolen from the host cell, (Galen, 2019 Part I). HIV is a chronic viral infection, in which viral particles (virons) will be constantly produced. Sometimes the infected cells remain alive and continue to produce viral particles. They will also continue to be infective and can transmit the virus to others, (Galen, 2019 Part II).
3. Immunity:
a. Which defenses protect us from infection by this bacterium? Intact mucosa is important because it is when the mucosal barrier is breached by abrasions that occur during sexual intercourse that the disease is introduced.
b. Does this pathogen induce a specific type of immune response? If so, which ones?
Normally, when a virus enters a cell, there will be an activation of cytotoxic T cells that can clear infection by killing virus-infected cells. Activation of these T cells depends on professional antigen-presenting cells, such as dendritic cells (DCs). The dendritic and T cells are the targets for HIV virus to invade and the HIV virus has the ability to somehow evade the cytotoxic T cells there by preventing them from killing the HIV infected cell before it replicates. So the immune response is disabled because T cells will be killed off to the point that the immune system is almost non-existent.
4. Infectious Disease Information:
A person infected with HIV has a damaged immune which makes it weak. This often leads to the person becoming infected with Opportunistic infections. These infections occur more often in people with weakened immune systems than in people with healthy immune systems. HIV-related Opportunistic infections include: pneumonia, Salmonella infection, candidiasis, toxoplasmosis and tuberculosis. If a person is infected with HIV, they need to be on an HIV medication which prevents severe damage to the immune system lessening their chances of getting opportunistic infections. These infections happen during the chronic phase of the disease where the immune system would be its weakest especially if a person is not on medication for the HIV, (Mayoclinic, 2018).
5. Epidemiology:
The person that has contracted HIV is the reservoir. When the HIV virus invades the host (cell), it begins to replicate by transcribing its RNA into the DNA of the host cell, the cell will then translate and transcribe the virus. The virus will begin to replicate, by attacking the CD4 cells (helper T cells). Once the CD4 cell is infected, it goes through the blood stream infecting other helper T cells.
6. Presentations:
A patient arrives in his physician office fearful that he may have been exposed to the HIV virus. He says that he hasn’t felt good for the last few weeks and is complaining of having a low grade fever, headache, muscle aches, and sore throat. He states that he had been intimate with someone 4 months ago and this person has recently tested positive for HIV. The physician draws blood to perform ELISA (enzyme-linked immunosorbent assay) and refers the patient to an infectious disease specialist. The specialist gets the results back that the patient has indeed contracted the virus. He immediately starts the patient on antiretroviral therapy: lamivudine-zidovudine and nevirapine. The physician explains to the patient that drug therapy adherence is a must. That people that have HIV are living long, productive lives as a result of immune system protection that these medications can potentially produce. It is essential that he eats a healthy diet, gets plenty of rest and refrains from any behaviors that are risky. The physician explains that he will monitor his viral load and CD4 T cell counts to determine his response to HIV treatment. CD4 T cell counts should be checked every three to six months. The physician explains that the treatment should lower his viral load so that it's undetectable. That doesn't mean his HIV is gone. It just means that the test isn't sensitive enough to detect it. You will also need to inform anyone that you have been intimidate with of your positive HIV status so they can be checked, (Mayoclinic, 2018).
7. Prevention:
The best way to prevent HIV infection is not having unprotected sex, do not share needles with anyone. Any risky practices such as IV drug use and having several sex partners increases the chances of getting HIV.
8. Treatment
There's no cure for HIV, but a treatment called antiretroviral therapy, or ART blocks the virus in different ways. ART is now recommended for everyone, regardless of CD4 T cell counts. It's recommended to combine three drugs from two classes to avoid creating drug-resistant strains of HIV.The classes of anti-HIV drugs include:
· Non-nucleoside reverse transcriptase inhibitors (NNRTIs) turn off a protein needed by HIV to make copies of itself. Examples include efavirenz (Sustiva), etravirine (Intelence) and nevirapine (Viramune).
· Nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs) are faulty versions of the building blocks that HIV needs to make copies of itself. Examples include Abacavir (Ziagen), and the combination drugs emtricitabine/tenofovir (Truvada), Descovy (tenofovir alafenamide/emtricitabine), and lamivudine-zidovudine (Combivir).
· Protease inhibitors (PIs) inactivate HIV protease, another protein that HIV needs to make copies of itself. Examples include atazanavir (Reyataz), darunavir (Prezista), fosamprenavir (Lexiva) and indinavir (Crixivan).
· Entry or fusion inhibitors Tblock HIV's entry into CD4 T cells. Examples include enfuvirtide (Fuzeon) and maraviroc (Selzentry).
· Integrase inhibitors work by disabling a protein called integrase, which HIV uses to insert its genetic material into CD4 T cells. Examples include raltegravir (Isentress) and dolutegravir (Tivicay), (CDC, 2018).
9. Clinical Relevance:
It's recommended to combine three drugs from two classes to avoid creating drug-resistant strains of HIV, (CDC. 2018). Healthcare workers are especially at risk for contracting HIV. Universal precautions is a mindset that all healthcare workers must adhere to increase likelihood of not contracting the virus from an infected patient.
A person that is sharing needles with another person, who is having unprotected sex are increasing the likelihood of getting HIV.
10. References:
Department of Health and Human Services, last reviewed Last Reviewed: November 6, 2018 HIV/AIDS: The Basics. https://aidsinfo.nih.gov/understanding-hiv-aids/fact-sheets/19/45/hiv-aids--the-basics
Engelkirk, Paul G., Engelkirk, Janet. (2015). Burton’s Microbiology for the Health Science, tenth edition. pg 1076 Philadelphia, PA. Wolters Kluwer Health Parker, N.,
https://www.questdiagnostics.com/dms/Documents/mlcp/National-Guides/National-MLCP-190-14-Human-Immunodeficiency_Virus_-Diagnosis.pdf (2016)
Parker, N., Schneegurt, M., Thi Tu, A., Forster, B., & Lister, P. (2018). Microbology. Houston, TX: Openstax.
Unit 6 Virus Presentation: Viral Structure, Cycles and Infections Part I Unit 6 Viruses https://classroom.galencollege.edu/courses/2516557/modules/items/44806742
Unit 6 Virus Presentation: Viral Structure, Cycle and Infections Part II Unit 6 Viruseshttps://classroom.galencollege.edu/courses/2516557/modules/items/44806742
Gulzar N., Copeland, KF. 2004 Jan;2(1):23-37. Review. CD8+ T-cells: function and response to HIV infection.https://www.ncbi.nlm.nih.gov/pubmed/15053338
https://www.mayoclinic.org/diseases-conditions/hiv-aids/diagnosis-treatment/drc-20373531Jan. 19, 2018
