Podcast
Questions and Answers
What is the primary mechanism by which retroviruses like HIV replicate?
What is the primary mechanism by which retroviruses like HIV replicate?
Which variant of HIV is the most predominant type found worldwide?
Which variant of HIV is the most predominant type found worldwide?
During the latent phase of HIV infection, what happens to CD4 T cells?
During the latent phase of HIV infection, what happens to CD4 T cells?
What percentage of sequence homology is found between the two variants of HIV?
What percentage of sequence homology is found between the two variants of HIV?
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What significant milestone regarding HIV was noted in 1981 in the USA?
What significant milestone regarding HIV was noted in 1981 in the USA?
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What is the primary mode of transmission for Trichomonas vaginalis?
What is the primary mode of transmission for Trichomonas vaginalis?
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Which symptom is most commonly reported by women infected with Trichomonas vaginalis?
Which symptom is most commonly reported by women infected with Trichomonas vaginalis?
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What form of replication does Trichomonas vaginalis utilize?
What form of replication does Trichomonas vaginalis utilize?
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In which population does Trichomonas vaginalis appear most frequently?
In which population does Trichomonas vaginalis appear most frequently?
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What is one reason why Trichomonas vaginalis poses a challenge for treatment?
What is one reason why Trichomonas vaginalis poses a challenge for treatment?
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Which of the following is a common symptom associated with initial HIV infection?
Which of the following is a common symptom associated with initial HIV infection?
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What is the primary type of cancer caused by persistent infection with high-risk HPV types?
What is the primary type of cancer caused by persistent infection with high-risk HPV types?
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What method is used for definitive diagnosis of HIV infection?
What method is used for definitive diagnosis of HIV infection?
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Which of the following describes a characteristic of the Human Papilloma Virus (HPV)?
Which of the following describes a characteristic of the Human Papilloma Virus (HPV)?
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Which of the following antiviral drug classes is NOT typically included in anti-retroviral therapy (ART)?
Which of the following antiviral drug classes is NOT typically included in anti-retroviral therapy (ART)?
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What is a major challenge in developing a vaccine for HIV?
What is a major challenge in developing a vaccine for HIV?
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Which of the following infections can indicate the onset of AIDS?
Which of the following infections can indicate the onset of AIDS?
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What is a key aspect of the treatment regimen for HIV?
What is a key aspect of the treatment regimen for HIV?
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Study Notes
Pathophysiology of Sexually Transmitted Infections
- HIV is a retrovirus, enveloped, positive-sense, single-stranded RNA virus. It has a reverse transcriptase enzyme, a polyhedral capsid, and a spiked envelope. Its size ranges from 80-146 nm.
- Two main variants exist: HIV-1, predominant globally, and HIV-2, primarily found in West Africa. HIV-2 shares 50% sequence homology with HIV-1.
- HIV-1's life cycle involves binding to CD4 cells (Helper T cells), fusion, core delivery, reverse transcription initiation, uncoating and reverse transcription completion, integration, transcription, translation, assembly, budding, release, and maturation.
- HIV's replication utilizes reverse transcriptase to convert RNA into DNA, creating a DNA-RNA hybrid intermediate.
- Reverse transcriptase degrades the RNA portion of this hybrid, then synthesizes a complementary strand of DNA using the DNA strand as a template, eventually forming double-stranded DNA.
Pathogenicity of HIV
- Body fights the virus initially, killing millions of CD4 cells in the latent phase.
- The body's inability to produce enough CD4 cells results in a decline in their numbers over 5-10 years.
- HIV virus numbers increase during this time.
- Other infections easily invade the system due to a compromised immune system (AIDS).
Epidemiology of HIV
- Discovered in young homosexual males in 1981, in the USA.
- Now a global issue.
- Estimated 39 million people were living with HIV in 2022, with two-thirds in the WHO African Region (25.6 million).
- In 2022, 630,000 people died from HIV-related causes and 1.3 million people acquired HIV.
- Sub-Saharan Africa is most affected by HIV, representing 71% of the global caseload.
- Transmission occurs through sexual contact and intravenous drug use, with contact with bodily fluids being comparatively rare.
HIV Symptoms
- Initial infections present symptoms like fever, fatigue, weight loss, diarrhea, and body aches.
- AIDS onset is characterized by opportunistic infections: Kaposi's sarcoma, disseminated herpes, toxoplasmosis, and pneumocystis pneumonia. These infections are not usually lethal in people with healthy immune systems.
Diagnosis of HIV
- Often initially mistaken for the flu because the initial symptoms are similar.
- The diagnosis involves monitoring CD4 cell counts.
- Serology testing for antibodies, rapid point-of-care testing, and PCR of RNA are diagnostic methods.
Treatment of HIV
- Antiretroviral therapy (ART) involves a cocktail of 3-4 antiviral drugs including nucleotide analogs, integrase inhibitors, protease inhibitors, and reverse transcriptase inhibitors.
- ART must be taken on a strict schedule; otherwise, its efficacy may be compromised.
- ART is expensive.
- ART stops HIV replication.
HIV Vaccine Development
- Vaccine development is difficult due to HIV's high mutability, ability to spread through syncytia, and ability to infect vital cells like macrophages, dendritic cells, and Helper T cells, which are normally stimulated by vaccines.
- Another challenge is the ethical difficulty of testing the vaccine on humans only.
Human Papillomavirus (HPV)
- Non-enveloped, double-stranded circular DNA virus.
- Causes genital warts, a common STI in the UK.
- Transmission mostly occurs through sexual contact.
- Genital warts appear as small, rough lumps around the vagina, penis, or anus.
- In 90% of cases, the body's immune system manages the infection on its own.
- Persistent high-risk HPV infections can lead to cervical cancer, the most common HPV-related cancer.
Trichomonas vaginalis
- A protozoan parasite, an obligate parasite that lives only in human hosts.
- Transmitted exclusively via sexual contact.
- Most often observed in people with other STIs or multiple sex partners.
- Characterized by four anterior flagella, an undulating membrane, a body approximately 15 μm in length, and a posterior flagellum (axostyle).
- The parasite replicates by binary fission within the human host.
- Existence in a cyst form is not observed, and it does not survive well in the external environment.
Trichomonas vaginalis - Symptoms
- Women: vaginosis, purulent, and odorous discharge, vaginal and cervical lesions, abdominal pain, painful urination, and painful sexual intercourse.
- Men: typically asymptomatic, but may present with urethra/bladder inflammation.
Trichomonas vaginalis - Treatment and Diagnosis
- Diagnosis: microscopic observation of trophozoites in vaginal/urethral secretions.
- Treatment: Nitroimidazole drugs are typically effective, but resistance in some strains exists.
Summary of STIs
- This presentation covered the pathogenesis (development and progression) of various STIs, including Chlamydia, Gonorrhea, Syphilis, Genital Warts/HPV, Genital Herpes, HIV/AIDS, and Trichomonas vaginalis.
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Description
This quiz covers the pathophysiology and pathogenicity of HIV, including its structure, life cycle, and replication process. Test your knowledge on the key differences between HIV-1 and HIV-2, and understand how the virus interacts with the immune system. Dive into the complexities of retroviral infections and their impact on human health.
