Lesson
Read the Virus as a Treatment Map
HIV is an enveloped retrovirus that uses host CD4 cells and three viral enzymes to convert RNA into a durable proviral template and produce infectious progeny.
- RNA retrovirus
- gp120 and gp41
- CD4
- CCR5 and CXCR4
- Genetic diversity
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Identify the essential structure
HIV carries two copies of positive-sense single-stranded RNA plus reverse transcriptase, integrase, and protease. The envelope displays gp120 and gp41, which coordinate attachment and fusion.
Explain cellular tropism
gp120 first engages CD4 and then a chemokine coreceptor, commonly CCR5 or CXCR4. CD4 T cells are central targets, while macrophages and dendritic cells also influence persistence and spread.
Connect replication to immune loss
Ongoing viral replication, direct and indirect cell injury, chronic immune activation, and impaired immune regeneration progressively reduce effective cell-mediated immunity.
Explain why resistance emerges
Reverse transcriptase is error prone and viral turnover is rapid. Combination ART suppresses diverse virus more completely, while incomplete exposure can select variants that survive the active drugs.
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Lesson
Follow the Life Cycle in Order
The HIV life cycle provides a sequence for organizing antiretroviral pharmacology rather than memorizing disconnected drug lists.
- Attachment
- Fusion
- Reverse transcription
- Integration
- Maturation
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Enter the cell
Attachment begins with gp120 binding to CD4 and a coreceptor. Attachment, post-attachment, CCR5, and fusion inhibitors act at different molecular contacts and are not interchangeable.
Build the provirus
Reverse transcriptase converts viral RNA to DNA. NRTIs act as substrate analogs after intracellular activation, while NNRTIs bind a distinct allosteric site. Integrase then inserts viral DNA into host DNA.
Use host machinery
The integrated provirus is transcribed and translated by host machinery. Viral RNA and polyproteins assemble at the cell membrane before budding.
Mature the particle
Viral protease cleaves polyproteins into functional components. Protease inhibition leaves immature, noninfectious particles even after budding has occurred.
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Lesson
Define the Exposure, Not the Identity
Transmission depends on infectious fluid, a susceptible route, exposure timing, and source virology. Accurate prevention counseling replaces stigma with mechanism.
- Sexual exposure
- Blood exposure
- Perinatal transmission
- PEP and PrEP
- U equals U
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Identify established routes
HIV can be transmitted through blood, semen, rectal and vaginal fluids, and breast milk when they reach susceptible mucosa, non-intact tissue, or the bloodstream. Casual contact, intact skin, food sharing, and ordinary household contact are not transmission routes.
Treat recent exposure as urgent
Qualifying occupational and nonoccupational exposures require immediate evaluation because PEP is time sensitive. PrEP supports ongoing prevention and belongs in a separate detailed module.
Use current perinatal guidance
ART, viral suppression, delivery planning, infant prophylaxis, and feeding guidance reduce transmission. Apply current perinatal recommendations rather than obsolete pregnancy letters or a universal adult shortcut.
Communicate U equals U precisely
Maintaining plasma HIV RNA below 200 copies per milliliter with ART prevents sexual transmission. U equals U depends on treatment continuity and monitoring and does not prevent other sexually transmitted infections.
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Lesson
Recognize the Course Without Waiting for Symptoms
Acute HIV can be clinically loud or silent, chronic infection may appear well, and advanced immune dysfunction can change the differential before the person recognizes a problem.
- Acute infection
- Chronic infection
- CD4 trajectory
- Stage 3 HIV
- Opportunistic disease
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Recognize acute infection
Fever, rash, pharyngitis, lymphadenopathy, headache, and myalgias can occur during early intense viremia, but none is specific. A negative antibody-only or early Ag/Ab result cannot close the case when exposure and symptoms strongly support acute HIV.
Do not trust clinical quiet
After the acute phase, a person may remain asymptomatic for years while untreated virus replicates. Symptoms are not a reliable gate for screening, diagnosis, or ART.
Interpret CD4 and HIV RNA differently
CD4 describes immune reserve and opportunistic risk. HIV RNA quantifies circulating viremia and is the most responsive marker of antiviral effect.
Define advanced disease
Stage 3 HIV is established by CD4 below 200 cells per cubic millimeter or an AIDS-defining condition. Either criterion is sufficient, and an urgent symptom-driven opportunistic evaluation can take priority over routine sequencing.
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Lesson
Resolve Each Diagnostic Branch
The laboratory algorithm uses an antigen-antibody screen, an HIV-1 and HIV-2 differentiation assay, and nucleic acid testing when the results are discordant or acute infection remains possible.
- Ag/Ab screening
- Differentiation assay
- HIV-1 NAT
- Acute infection
- Self-testing
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Begin with a laboratory Ag/Ab assay
The standard laboratory algorithm starts with an HIV-1 and HIV-2 antigen-antibody immunoassay. A nonreactive result usually ends the algorithm unless very early infection is suspected.
Differentiate a reactive screen
A reactive initial assay is followed by an HIV-1 and HIV-2 antibody differentiation immunoassay. A positive supplemental result establishes the antibody diagnosis and type.
Resolve discordance with NAT
When the differentiation assay is negative or indeterminate after a reactive screen, perform HIV-1 nucleic acid testing. A positive NAT supports acute HIV-1, while a negative NAT usually indicates a false-reactive initial screen, with HIV-2 follow-up when indicated.
Treat self-tests as preliminary
A reactive home antibody result requires laboratory confirmation. A negative test can be falsely reassuring when taken before the assay window has closed or during antiretroviral prevention exposure.
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Lesson
Turn Diagnosis Into Care Immediately
Rapid ART is a care-delivery strategy that pairs early treatment with specimen collection, medication access, follow-up, and a planned review of pending information.
- Confirm diagnosis
- Same-day ART
- Acute HIV
- Pending data
- Linkage
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Collect before treating when feasible
Confirm the diagnosis and draw HIV RNA, CD4, genotype, safety, and coinfection studies before the first dose when this can be done promptly. Do not routinely wait for every result to return.
Offer ART immediately
NIH recommends ART for all people with HIV and initiation immediately or as soon as possible. The initial regimen should remain robust while resistance, HBV, pregnancy, kidney, and interaction information is pending.
Treat likely acute HIV
A positive HIV RNA with a negative or indeterminate antibody result can make acute HIV highly likely. Draw a resistance sample and begin ART without waiting for antibody maturation while confirmation proceeds.
Build real linkage
Assign ownership for result review, medication access, insurance, pharmacy supply, adherence support, confidentiality, mental health, substance use, transport, and the next appointment. A prescription without this system is incomplete linkage.
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Lesson
Build the Baseline That Changes Decisions
Baseline evaluation confirms the virologic and immune state, identifies organ and coinfection constraints, and reveals prior antiretroviral exposure and barriers to care.
- HIV RNA
- CD4
- CBC and chemistry
- Hepatitis
- Prior PrEP or PEP
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Measure virus and immunity
Obtain plasma HIV RNA and CD4. HIV RNA establishes the response baseline, while CD4 guides opportunistic-infection risk, prophylaxis, and immunologic follow-up.
Establish organ safety
Obtain CBC, kidney and liver data, glucose, lipids, urinalysis, and pregnancy testing when relevant. Interpret results in the context of the candidate regimen and comorbid disease.
Define viral coinfections
Assess hepatitis A, B, and C status and screen for sexually transmitted and opportunistic infections as indicated. HBV status can determine whether an HIV regimen also needs two HBV-active agents.
Ask about prevention exposure
Document oral or injectable PrEP, PEP, prior ART, last long-acting injection, adherence, and resistance results. A person can be treatment naive while still having meaningful antiretroviral exposure.
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Lesson
Order the Test That Answers the Regimen Question
Genotype, integrase resistance, HLA-B*5701, and tropism testing answer different questions and should not be substituted for one another.
- RT and protease genotype
- Integrase genotype
- HLA-B*5701
- Tropism
- Pretreatment sample
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Obtain baseline genotype
Standard pretreatment genotype focuses on reverse transcriptase and protease mutations. Draw it before ART when feasible, but do not routinely delay rapid treatment while awaiting the result.
Add integrase when concern is real
Include the integrase gene after long-acting cabotegravir exposure, relevant INSTI treatment or PEP, or another credible transmitted-resistance scenario.
Protect against abacavir hypersensitivity
Obtain HLA-B*5701 before abacavir. A positive result contraindicates use, and a person with suspected abacavir hypersensitivity must never be rechallenged.
Confirm the entry pathway
Use a tropism assay before maraviroc because the drug blocks CCR5 and cannot treat virus that relies on CXCR4 or dual-mixed pathways.
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Lesson
Monitor the Decision, Not the Habit
Viral load, CD4, and safety studies have different purposes and different useful frequencies once treatment is stable.
- HIV RNA
- CD4
- Suppression
- Blips
- Safety monitoring
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Follow viral load
Check HIV RNA after ART initiation or modification and continue periodic confirmation. Effective therapy usually suppresses below assay detection within months, but the timing depends on baseline viremia, regimen, adherence, and clinical context.
Scale CD4 monitoring
CD4 remains important early and when immune function is low. Frequency can decrease after durable viral suppression and immune recovery when another result would not change prophylaxis or care.
Investigate incomplete response
Review missed exposure, food and cation requirements, interactions, absorption, dispensing history, tolerability, and resistance. Distinguish an isolated low-level blip from persistent rebound using magnitude and trend.
Target safety surveillance
Monitor kidney, liver, marrow, metabolic, bone, psychiatric, and other risks according to the actual regimen and patient rather than one universal interval.
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Lesson
Build Durable Suppression
ART combines active agents to achieve full suppression, preserve immune function, prevent transmission, and protect each component from resistance.
- Treatment goals
- Combination therapy
- Resistance barrier
- Continuity
- No functional monotherapy
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Name all treatment goals
ART reduces morbidity and mortality, restores or preserves immune function, sustains virologic suppression, and prevents sexual and perinatal transmission. Current ART controls HIV but does not eradicate the reservoir.
Use a complete regimen
Select a potent rational combination based on genotype, prior exposure, comorbidities, interactions, pregnancy context, organ function, and preference. Do not add one active drug to a failing background.
Understand resistance barrier
Drug classes and agents vary in the number and type of changes needed for clinically important resistance. High-barrier regimens improve durability but do not solve poor absorption or inaccessible refills.
Prevent interruptions
Viral rebound can follow unplanned gaps. Protect supply across discharge, travel, insurance changes, disasters, and formulation transitions, and never stop selected components casually.
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Lesson
Choose an Initial Path That Survives Pending Data
Current initial therapy usually uses a potent second-generation INSTI-based regimen, but HBV, prior prevention exposure, resistance, and incomplete baseline data can redirect the first choice.
- Second-generation INSTI
- NRTI backbone
- HBV
- Two-drug criteria
- CAB-LA breakthrough
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Start from the current default
For most people, NIH recommends bictegravir with TAF and FTC, or dolutegravir with TAF or TDF plus FTC or 3TC. Exact selection depends on current guidance, kidney and bone status, interactions, pregnancy context, access, and resistance.
Preserve HBV treatment
Active HBV generally requires TAF or TDF plus FTC or 3TC as part of a complete HIV regimen. Do not leave HBV on a single low-barrier agent or stop HBV-active drugs without a flare plan.
Respect two-drug boundaries
Dolutegravir plus lamivudine can be used in selected people, but not as a blind option when HBV status or genotype is unavailable, with relevant resistance, or when HIV RNA exceeds the supported threshold.
Handle CAB-LA breakthrough separately
After HIV acquisition during or after CAB-LA exposure, obtain integrase testing and use a regimen that remains active while results are pending, often a boosted darunavir-based pathway when INSTI sensitivity is unknown.
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Lesson
Make the Regimen Livable
Durable HIV care joins pharmacology to access, preference, privacy, mental health, reproductive goals, structural conditions, and a respectful therapeutic relationship.
- Adherence
- Access
- Shared decisions
- Confidentiality
- Stigma-free care
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Assess adherence without judgment
Ask about doses, schedule, food, cations, interactions, adverse effects, refill supply, privacy, cognition, mood, substance use, housing, transport, and competing priorities. The same missed dose pattern can have very different causes.
Choose together
Balance efficacy and resistance with formulation, pill burden, injection preference, schedule, disclosure concerns, pregnancy goals, cost, pharmacy access, and the person's priorities.
Use precise respectful counseling
Use person-first language, protect confidentiality, explain the difference between HIV and stage 3 disease, and communicate U equals U accurately. Fear and shame interfere with testing and engagement.
Keep education in scope
This module supports professional learning and cannot diagnose or prescribe for an individual. Real decisions require current patient data, current guidance, and accountable HIV clinicians and pharmacists.
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Module test
Check the connections.
Each attempt draws 10 questions from the complete 216 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Lecture material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.