HIV Treatment and Transmission Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Rapid tests can yield results within ______ minutes.

The primary goals of therapy in HIV-infected patients include reducing HIV-related morbidity and mortality, improving quality of life, and ______ virus replication.

suppressing

Antiretroviral agents are administered in combinations of different drug classes termed ______.

cART

Condom use reduces the incidence of new HIV infections by ______ to 95%.

80 Signup and view all the answers

Male circumcision can lead to a ______% risk reduction in the transmission of HIV.

60 Signup and view all the answers

HIV's env gene codes for a large protein that is cleaved to gp41 and gp______.

120 Signup and view all the answers

HIV enters target cells by fusion of its viral envelope with the cellular ______.

membrane Signup and view all the answers

The reverse transcriptase enzyme forms a double-stranded ______ copy of the viral RNA.

DNA Signup and view all the answers

HIV replication involves the initial attachment through the glycoprotein gp120 and the ______ receptor.

co Signup and view all the answers

The state in which HIV integrated into host DNA is referred to as the ______.

provirus Signup and view all the answers

Latency involves the progressive loss of ______ in lymphoid tissues.

CD4+ T cells Signup and view all the answers

HIV-infected CD4+ T lymphocytes produce about ______% to 99% of the virus in the blood.

93 Signup and view all the answers

A blood CD4+ T cell count below ______ cells per mm3 indicates susceptibility to infections.

200 Signup and view all the answers

Retroviral reverse transcriptases have a high misincorporation rate due to their lack of ______ activity.

proofreading Signup and view all the answers

Clinical AIDS is marked by increased susceptibility to infections and some types of ______.

cancers Signup and view all the answers

A single viral replication cycle of HIV lasts approximately ______ to 2 days.

1 Signup and view all the answers

The half-life of the virus in plasma is around ______ hour.

one Signup and view all the answers

Less than 1% of the virus in plasma is produced by latently infected CD4+ ______, which become activated and start producing virus.

T-cells Signup and view all the answers

HIV infection can be diagnosed by detecting antibodies to the virus or the virus itself, such as ______ antigen.

HIV p24 Signup and view all the answers

Monocytes or macrophages contribute to ______% to 7% of the virus found in blood.

1 Signup and view all the answers

Current tests for HIV often use antigens derived from cloned recombinant HIV ______ genes.

gag, pol and env Signup and view all the answers

According to UNAIDS, between 33 and 37 million people were living with ______ in 2013.

HIV Signup and view all the answers

Combination assays, known as 4th generation assays, detect anti-HIV and ______ antigen in a single EIA.

p24 Signup and view all the answers

New infections in 2013 amounted to 1.9 million in adults and to ______ in children.

240,000 Signup and view all the answers

Direct detection methods like ______ are necessary during the early acute stage of HIV infection.

PCR Signup and view all the answers

Globally, the most frequent route of transmission is by ______.

sexual intercourse Signup and view all the answers

The risk of transmitting or acquiring infection varies greatly and is linked to viral ______ in genital fluids.

shedding Signup and view all the answers

Monitoring disease progression requires measuring plasma ______ load.

virus Signup and view all the answers

The duration between primary infection and progression to clinical disease averages about ______ years.

10 Signup and view all the answers

HIV proviral ______ can be detected in infected cells to diagnose infection in infants.

DNA Signup and view all the answers

The absence of proviral DNA at ______ months of age excludes HIV infection in babies not being breastfed.

3 Signup and view all the answers

In untreated cases, death usually occurs within ______ years after the onset of clinical symptoms.

2 Signup and view all the answers

Following primary infection, there is a 4- to ______-day period between mucosal infection and initial viremia.

11 Signup and view all the answers

The clinical course of HIV infection culminates in immune ______.

deficiency Signup and view all the answers

Acute HIV syndrome: patients may experience a mild acute illness with fever and ______, correlating with the initial viremia.

malaise Signup and view all the answers

HIV is classified under the family ______.

Retroviridae Signup and view all the answers

The two distinct types of human AIDS viruses are HIV-1 and ______.

HIV-2 Signup and view all the answers

AIDS was first described in the United States in ______.

1981 Signup and view all the answers

HIV-1 variants are classified into three genetic groups: major (M), outlier (O), and ______.

non-M, non-O (N) Signup and view all the answers

Subtype ______ of HIV-1 is most frequently found in western countries.

B Signup and view all the answers

The genome of HIV contains the genes gag, pol, and ______.

env Signup and view all the answers

The enzyme ______ is utilized during the reverse transcription process in HIV.

reverse transcriptase Signup and view all the answers

Long terminal repeat sequences (LTR) at both ends of the genome contain ______ and enhancer sequences.

promoter Signup and view all the answers

Study Notes

Human Immunodeficiency Viruses (HIV)

HIV is a retrovirus, belonging to the Retroviridae family and Lentivirus genus.
Two distinct types exist: HIV-1 and HIV-2.
AIDS was first recognized in the United States in 1981, initially linked to homosexual men.
Twenty years later, it was recognized as a worldwide pandemic, with over 35 million people infected globally. Heterosexual contact is now the primary mode of infection.

HIV Classification

HIV-1 and HIV-2 exhibit considerable sequence variations, leading to different subtypes with varying geographical distribution and risk group associations.
HIV-1 is categorized into three genetic groups: Major (M), Outlier (O), and Non-M, Non-O (N).
The prevalent pandemic group (M) is further classified into subtypes (A, B, C, D, F, G, H, J, K) and circulating recombinant forms (CRFs), often combining multiple subtypes.
Subtype B is prevalent in Western countries, whereas C, E, and F subtypes are significant in other regions. HIV-1 diversity is highest in sub-Saharan Africa.
HIV-2 also has subtypes, with 2 epidemic (A and B) and 5 non-epidemic (C-G) subtypes, arising from multiple simian-to-human transmissions.

HIV Structure & Biology

All retroviruses, including HIV, have a lipid envelope surrounding a viral core.
The envelope contains viral proteins.
The core contains two molecules of positive single-stranded RNA and the enzyme reverse transcriptase.
The viral genome has genes for gag, pol, and env proteins.
- gag codes for proteins found in the viral particle.
- pol codes for enzymes involved in replication (protease, reverse transcriptase, integrase).
- env codes for a large protein that becomes gp41 (transmembrane) and gp120 (envelope) glycoproteins. The LTRs (long terminal repeats) contain promoter and enhancer sequences at the genome ends.

HIV Life Cycle

Retroviruses replicate from a DNA copy of their RNA.
Initial HIV attachment to target cells involves interaction of gp120 with the CD4 molecule on T helper lymphocytes (and other cells). Then gp41 fuses with the cellular membrane.
The virus interacts with a second (co-) receptor (e.g., CCR5 or CXCR4).
The RNA genome is released into the cell cytoplasm, where reverse transcriptase forms a double-stranded DNA copy.
This DNA moves to the nucleus and is integrated into the host cell DNA, referred to as a provirus, therefore permanent infection.
Transcription of mRNA from the provirus occurs using host RNA polymerase II, synthesizing viral proteins.
Viral components assemble at the cell membrane.
New virions bud off from the cell. A substantial number (10¹⁰) of virus particles are produced daily. A single viral replication cycle takes 1-2 days.

HIV Replication & Viral Load in the Blood

The infected person has an accumulation of virus variants due to two phenomena.
- The reverse transcriptase lacking a proof-reading mechanism has a high misincorporation rate leading to mutation.
- Genomic recombination can occur after co-infection with different viruses, incorporating both viral RNA strands into the same particle.
Productively infected CD4+ T lymphocytes are the main source of circulating HIV in the blood with a half-life of 0.7-0.2 days.
Other sources of virus include longer-lived cells such as monocytes/macrophages (14 ± 7.5 days) and latently infected CD4+ T cells with a very slow decay rate (6 - 44 months). Less than 1% of plasma virus is from latently infected CD4+ cells.

HIV Diagnosis

HIV diagnosis uses detection of antibodies, p24 antigen, or viral RNA/DNA.
Current tests often involve HIV antigens produced by recombinant viral genes or synthetic peptides.
Western blot is a confirmatory method.
Combining assays that look for both antibodies and antigens can increase diagnostic sensitivity in primary infections.
PCR is also used for direct detection, during the early acute phase, in infants, and for monitoring progression.
Analysis of HIV DNA in blood samples (using PCR) can be used to diagnose infections in newborns.

HIV Epidemiology

In 2013, the global prevalence of HIV was estimated 0.7-0.8% in people older than 15 years.
Sub-Saharan Africa has the highest reported prevalence at 4.7% and 2/3 of the total global infection.
Other prevalent regions include the Caribbean and Eastern Europe/Central Asia.

HIV Transmission

Primarily transmitted through sexual intercourse, mother-to-child (congenitally/postnatally via breastfeeding), or parenteral inoculation (e.g., intravenous drug use).
Risk is proportional to viral load determined by RT-PCR. Infectious HIV-1 particles and/or infected cells are present in semen and mucosal secretions.

HIV Clinical Significance

The duration between primary infection and clinical AIDS averages about 10 years.
Death from untreated AIDS commonly occurs 2 years after clinical symptoms onset.
Following primary infection, acute infection lasts 4-11 days followed with initial viremia, which continues for 8-12 weeks, widely disseminating throughout the body.
Clinical stages: Acute HIV Syndrome, Latency Period, Clinical AIDS (characterized by increased susceptibility to infections and some cancers).

HIV Treatment & Prevention

Primary treatment goals include minimizing morbidity and mortality, restoring immunity, and suppressing viral replication.
Combined antiretroviral therapy (CART), using multiple drug classes, is commonly used to maximize effectiveness and minimize drug resistance emergence.
Preventing HIV transmission involves reducing exposure to viral inoculum (e.g., Condoms, early identification, counseling, and treatment of infected individuals, and male circumcision).

HIV Laboratory Markers Associated with Progression

Decreasing number of CD4+ T lymphocytes.
Increasing proportion of infected CD4+ cells.
Increasing titre of HIV RNA in plasma (viral load).
Detectable p24 antigen in plasma.
Isolation of HIV in culture.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz tests your knowledge on HIV therapy, transmission, and the biological mechanisms of HIV infection. From understanding rapid testing to the impact of circumcision on transmission risk, assess your grasp on how to manage and prevent HIV infection effectively.