1. HIV MICROBIOLOGY – THE CORE POINTS

1.1 Type, family, genome

• Family: Retrovirus, genus Lentivirus (slow, chronic infections).
• Genetic material: Single-stranded, positive-sense RNA, two copies (diploid).
• Enveloped virus → very sensitive to heat, drying, detergents.

Key high-yield:

• HIV = enveloped, diploid, +ssRNA retrovirus that uses reverse transcriptase and integrates as provirus in host DNA.

1.2 Structure (what you MUST remember)

Think: Envelope → Capsid → Core enzymes → Genome

• Envelope: host-cell lipid bilayer with:
• gp120 – surface glycoprotein, binds CD4 + co-receptor (CCR5/CXCR4). (ScienceDirect)
• gp41 – transmembrane glycoprotein, mediates fusion of viral + cell membrane.
• Matrix: p17 protein just under envelope. (NCBI)
• Capsid: cone-shaped, made of p24. Highly antigenic (p24 antigen test). (NCBI)
• Core enzymes (all in pol gene):
• Reverse transcriptase – RNA → DNA
• Integrase – inserts viral DNA into host genome
• Protease – cleaves viral polyproteins for maturation (NCBI)
• Genes:
• gag → core proteins (p24, p17)
• pol → enzymes (RT, integrase, protease)
• env → gp160 → cleaved to gp120 + gp41 (Wikipedia)
• Accessory genes: tat, rev, nef, vif, vpr, vpu – regulate replication & virulence.

20% exam memory:

gag → group core (p24); pol → polymerase (RT, integrase, protease); env → envelope (gp120, gp41).

1.3 Replication cycle (VERY exam-friendly)

1. Attachment:
• gp120 binds CD4 receptor on T-helper cells, macrophages, dendritic cells
• Needs co-receptor: CCR5 (early/mucosal), CXCR4 (late/T-cell-tropic).
2. Fusion & entry:
• gp41 mediates membrane fusion → viral core enters.
3. Reverse transcription:
• Reverse transcriptase converts ssRNA → dsDNA in cytoplasm.
4. Integration:
• Viral DNA transported to nucleus, integrase inserts into host genome = provirus.
5. Transcription & translation:
• Host RNA polymerase II makes viral mRNA + genomic RNA.
6. Assembly:
• Gag, Pol, Env proteins and RNA assemble at cell membrane.
7. Budding & maturation:
• Virus buds out; protease cleaves polyproteins → mature infectious virion.

Drug targets:

• Entry/CCR5 blockers, fusion inhibitors, NRTI/NNRTI (RT), integrase inhibitors, protease inhibitors.

1.4 Transmission & pathogenesis (for pregnancy context)

Main modes:

• Sexual (vaginal, anal; semen, vaginal secretions, rectal secretions)
• Blood (transfusion, needles, occupational)
• Mother → child:
• In utero (transplacental),
• Intrapartum (exposure to blood, genital secretions),
• Postnatal (breast milk). (World Health Organization)

Without any prophylaxis, vertical transmission risk is ~15–45%; with effective ART + obstetric + infant prophylaxis, risk can be reduced to <2%. (World Health Organization)

Main pathogenesis idea:

• Progressive infection & destruction of CD4 T cells → immunodeficiency → opportunistic infections, malignancy.

1.5 Lab diagnosis (link to pregnancy screening)

• Screening in pregnancy:
• 4th-generation combined Ag/Ab test: p24 antigen + HIV-1/2 antibodies → detects infection earlier.
• Confirmation:
• Supplemental antibody differentiation tests / immunoblot / NAAT as per national protocol.
• Viral load (HIV RNA):
• Quantitative PCR – key for monitoring ART and deciding mode of delivery.
• CD4 count:
• Immune status, OI risk; less central to obstetric decisions now (viral load more important).

Most PMTCT guidelines: test all pregnant women for HIV with high-quality testing & repeat in high-risk. (PrEPWatch)

2. MANAGEMENT OF PREGNANT WOMAN WITH HIV (HIGH-YIELD PMTCT)

We’ll structure into:

1. Pre-pregnancy / first contact
2. Antenatal
3. Intrapartum
4. Postpartum (mother)
5. Newborn management
6. Breastfeeding

Use this as your essay framework.

2.1 Pre-pregnancy & first antenatal contact

Goals:

• Protect mother’s health
• Achieve undetectable viral load before/during pregnancy
• Prevent MTCT

Key steps:

1. HIV testing and counselling
• Offer HIV test to all pregnant women, preferably at booking visit. (PrEPWatch)
2. If already known HIV-positive:
• Confirm ART regimen, adherence, side-effects.
• Check baseline viral load, CD4, screen for co-infections (HBV, HCV, syphilis, TB). (Centre for Health Protection)
3. If newly diagnosed in pregnancy:
• Start ART as soon as possible, regardless of CD4 or clinical stage (“treat all” strategy). (Centre for Health Protection)

High-yield ART principle (WHO-style):

• Triple ART for ALL pregnant & breastfeeding women, life-long.
• Common backbone: dolutegravir + 2 NRTIs (e.g., TDF + 3TC/FTC), depending on national protocol. (Centre for Health Protection)

2.2 Antenatal management

A. Routine ANC + HIV-specific care

• Standard obstetric care: anaemia, BP, diabetes, fetal growth, ultrasound etc.
• HIV-specific:
• Continue or start ART immediately.
• Aim for viral load undetectable (<50 copies/mL) by delivery.
• Repeat viral load at least once in 3rd trimester (around 34–36 weeks). (Centre for Health Protection)
• Screen & treat OIs; give co-trimoxazole prophylaxis if indicated (low CD4) as per local guidelines.
• Vaccinations: as per guidelines (e.g., influenza, Tdap, HBV if non-immune).

B. Management of other infections / risk factors

• STIs, bacterial vaginosis, UTIs – treat promptly (increase MTCT risk if untreated).
• Syphilis, HBV, HCV – part of triple EMTCT (HIV, syphilis, hepatitis B). (PrEPWatch)
• Counsel about adherence, condom use (prevent new HIV strain & reinfection), partner testing.

C. Obstetric procedures in pregnancy

• Invasive prenatal diagnosis (CVS, amniocentesis, etc.) – if needed:
• Prefer after viral load suppressed, use experienced operator, try to avoid transplacental puncture if possible.

2.3 Intrapartum management (labour & delivery)

Key exam concept = mode of delivery depends on viral load near term.

2.3.1 Mode of delivery

Guideline trends (BHIVA, NIH, others):

• If HIV RNA ≤ 50 copies/mL (or “undetectable”) at 36 weeks:
• Vaginal delivery is acceptable, MTCT risk extremely low. (ACOG)
• If HIV RNA > 1000 copies/mL or unknown near delivery:
• Scheduled elective Caesarean section at 38 weeks recommended to reduce MTCT. (ACOG)
• If 50–1000 copies/mL:
• Many guidelines support vaginal with good ART and no other risk factors, but some consider CS; decisions are individualized. (Southern Eastern Sydney Health)

For exams, the safe, simple rule to quote:

VL < 50 → Vaginal ok

VL > 1000 or unknown → Elective LSCS at 38 weeks

Intermediate → Individualize; many still allow vaginal if good ART & obstetric indications.

2.3.2 Intrapartum precautions

• Avoid procedures that increase fetal exposure to maternal blood:
• Avoid artificial rupture of membranes early unless obstetrically necessary.
• Avoid fetal scalp electrodes, fetal scalp blood sampling, routine episiotomy, instrumental delivery if possible.
• Minimise duration of ruptured membranes (≤4 hours particularly if high VL).
• Maternal IV zidovudine in labour is now mostly reserved for high viral load / unknown ART settings depending on protocol; many modern guidelines rely mainly on full ART and neonatal prophylaxis. (ClinicalInfo)

2.4 Postpartum management of the mother

• Continue lifelong ART; adjust regimen if needed (e.g., switch back from pregnancy-friendly to usual regimen).
• Manage:
• Postnatal complications, wound care, anaemia etc.
• Mental health, adherence support, contraception.

Contraception:

• Offer effective postpartum contraception:
• Long-acting reversible (implant, IUD – taking into account STI risk, anaemia, thrombocytopenia),
• Combined hormonal methods may have interactions with some ART (especially older NNRTIs, PIs).
• Aim to space pregnancies and prevent unintended pregnancies – part of EMTCT strategy. (Centre for Health Protection)

3. MANAGEMENT OF THE BABY (PMTCT – NEONATAL SIDE)

3.1 Immediately after birth

• Clamp cord early per usual practice; no special timing is strongly recommended solely for HIV now.
• Wipe and dry the baby; no need to separate from mother if she is stable.
• Bathing: some protocols bath early to remove blood, but not universally mandated.

3.2 Infant antiretroviral prophylaxis

Exact regimen depends on maternal viral load, ART, feeding choice, local guideline. General pattern from WHO/NIH/BHIVA:

• If the mother is on ART and VL suppressed:
• Singleton prophylaxis with oral zidovudine (AZT) or nevirapine for 2–6 weeks. (Centre for Health Protection)
• If maternal high viral load / late diagnosis / no ART:
• Enhanced prophylaxis with 2 or 3 drugs (e.g., zidovudine + lamivudine ± nevirapine) for a longer period (up to 12 weeks) as per guideline. (ClinicalInfo)

3.3 Infant testing & follow-up

• Early infant diagnosis (EID):
• HIV DNA/RNA PCR at around 4–6 weeks, earlier if high-risk. (PrEPWatch)
• Further PCRs depending on feeding:
• During breastfeeding and after cessation (e.g., 6 weeks after stopping).
• Serology (antibody test):
• After 18 months, to confirm HIV-negative status (maternal antibodies gone).
• Ensure routine immunizations (including BCG, live vaccines usually ok for HIV-exposed but uninfected; tailor if HIV-infected).

4. BREASTFEEDING & HIV (VERY EXAM-RELEVANT & RAPIDLY EVOLVING)

4.1 Risk vs benefits

• HIV can be transmitted via breastmilk.
• Without ART, additional postnatal transmission risk ≈ 5–20% depending on duration & feeding pattern. (PubMed Central)
• With effective maternal ART and infant prophylaxis, risk is now <1% but not zero. (World Health Organization)

4.2 WHO recommendations (global context)

WHO now recommends (especially in low- and middle-income settings): (World Health Organization)

• Mothers with HIV on effective ART and with support for adherence should:
• Exclusively breastfeed for first 6 months.
• Then introduce complementary foods and continue breastfeeding to at least 12 months, and may continue to 24 months or longer.
• Exclusive breastfeeding is safer than mixed feeding where AFASS criteria (Acceptable, Feasible, Affordable, Sustainable, Safe) for formula are not met.

High-income country guidelines (e.g., USA, Europe) now increasingly support shared decision-making, and allow breastfeeding when viral load is undetectable, with counselling that the risk is very low but not zero.

Exam take-home:

• Quote your national guideline if specified. Globally:

ART-adherent mother + suppressed viral load → exclusive breastfeeding recommended for 6 months, then complementary feeding + breastfeeding up to ≥12–24 months, with infant prophylaxis and regular testing.

5. THE “20% FOR 80% MARKS” SUMMARY

If you are writing a short 10-mark answer, you can condense to:

5.1 Microbiology – must-write points

• HIV = enveloped, diploid, +ssRNA retrovirus (Lentivirus) that attacks CD4 T cells.
• Structure:
• Envelope gp120/gp41, capsid p24, matrix p17, enzymes RT, integrase, protease, genes gag, pol, env.
• Replication:
• gp120 binds CD4+CCR5/CXCR4 → fusion → reverse transcription (RT) → integration (integrase) → transcription → assembly → budding & protease-dependent maturation.
• Transmission:
• Sexual, blood, and vertical (pregnancy, labour, breastfeeding).
• Lab:
• 4th-gen Ag/Ab test, confirmatory tests, viral load for monitoring and delivery planning, CD4 for immune status.

5.2 Management of HIV in pregnancy – must-write points

1. Antenatal
• Offer routine HIV testing to all pregnant women.
• Start lifelong triple ART ASAP, regardless of CD4; aim for undetectable VL at delivery.
• Monitor viral load in 3rd trimester, manage co-infections & STIs, counsel on adherence & partner testing.
2. Intrapartum
• Mode of delivery based on viral load:
• VL < 50 copies/mL → vaginal delivery acceptable.
• VL > 1000 or unknown → elective CS at 38 weeks to reduce MTCT.
• Avoid invasive procedures; minimise ROM time; consider intrapartum IV AZT in specific high-risk situations per local protocol.
3. Postpartum (mother)
• Continue lifelong ART.
• Contraceptive counselling; manage routine postpartum issues.
4. Newborn
• Give ARV prophylaxis (at least 2–6 wks, longer/multi-drug if high-risk).
• Early infant diagnosis (PCR) at ~4–6 weeks; follow-up testing.
• Routine immunizations + HIV-specialist follow-up.
5. Breastfeeding
• With effective maternal ART and good adherence, WHO recommends exclusive breastfeeding for 6 months and continued breastfeeding with complementary feeding up to 12–24 months, with infant prophylaxis and ongoing testing, acknowledging <1% residual risk. (World Health Organization)

.

🧠 EXAM REFLEX BLOCK — HIV MICROBIOLOGY & PREGNANCY (PMTCT)

Use this when the examiner gives one keyword and expects a full, correct answer fast.

🔹 HIV — MICROBIOLOGY (REFLEX ANSWERS)

• Virus type: Enveloped, diploid, +ssRNA*2 Retrovirus (Lentivirus)
• Key enzymes: Reverse transcriptase, Integrase, Protease
• Key proteins:
• gp120 → binds CD4 + CCR5/CXCR4
• gp41 → membrane fusion
• p24 → capsid (early antigen)
• Genes:
• gag → p24, p17
• pol → RT, integrase, protease
• env → gp120, gp41
• Core concept:

→ Reverse transcription → integration as provirus → lifelong infection

🔹 REPLICATION (ONE-LINE FLOW)

Attachment (gp120–CD4–CCR5/CXCR4) → Fusion (gp41) → RT → Integration → Transcription → Assembly → Budding → Protease-mediated maturation

🔹 TRANSMISSION (REFLEX TRIAD)

• Sexual
• Blood
• Vertical: In utero + Intrapartum + Breastfeeding

📌 Without ART: 15–45%

📌 With ART + PMTCT: <2%

🔹 LAB DIAGNOSIS (PREGNANCY-FOCUSED)

• Screening: 4th-generation Ag/Ab test (p24 + Ab),p24 highest 2–3 weeks post-infection(high viral replication)
• Monitoring: HIV RNA viral load (PCR) ← MOST IMPORTANT for delivery planning
• CD4 count: Immune status (less obstetric relevance now)) ,<200-AIDS-defining (PCP risk-TMP-SMX),<50-CMV infection

🔹 PMTCT — CORE MANAGEMENT LOGIC

🟢 Antenatal

• Test ALL pregnant women
• Start lifelong triple ART immediately (regardless of CD4)
• Goal: Undetectable viral load by delivery
• Repeat viral load at 34–36 weeks

🟢 Intrapartum — MODE OF DELIVERY (EXAM GOLD)

• VL < 50 copies/mL → ✅ Vaginal delivery
• VL > 1000 or unknown → ✅ Elective LSCS at 38 weeks
• 50–1000 → Individualize (often vaginal if good ART)

🚫 Avoid ARM, scalp electrodes, fetal scalp sampling, prolonged ROM

🟢 Postpartum (Mother)

• Continue lifelong ART
• Contraceptive counselling (drug interactions!) Barrier - IUCD

🔹 NEONATE (PMTCT SIDE)

• Low-risk baby:

→ Single-drug prophylaxis (AZT or NVP) 2–6 weeks

• High-risk baby:

→ 2–3 drug prophylaxis, longer duration

• Testing:
• PCR at 4–6 weeks,6months
• Final antibody test after 18 months

🔹 BREASTFEEDING — EXAM-SAFE STATEMENT

• HIV can transmit via breast milk
• With effective maternal ART + adherence + infant prophylaxis:
• Residual risk <1% (not zero)
• World Health Organization recommendation:

→ Exclusive breastfeeding 6 months, then complementary feeding + breastfeeding up to 12–24 months

📌 Exclusive breastfeeding safer than mixed feeding

🎯 ULTIMATE ONE-PARAGRAPH EXAM ANSWER

HIV is an enveloped diploid positive-sense RNA retrovirus that infects CD4 T cells via gp120 binding to CD4 and CCR5/CXCR4, undergoes reverse transcription, integration, and protease-dependent maturation. In pregnancy, universal screening and lifelong triple ART aiming for undetectable viral load reduces mother-to-child transmission to <2%. Mode of delivery depends on viral load, with vaginal delivery acceptable if suppressed and elective caesarean at 38 weeks if viral load is high or unknown. Neonates receive antiretroviral prophylaxis and early PCR testing, and breastfeeding is recommended under effective ART with counselling on residual risk.

MASTER TABLE

🧬 TABLE 1 — HIV MICROBIOLOGY (CORE FACTS)

🧫 TABLE 2 — HIV STRUCTURE (PROTEINS, GENES, FUNCTIONS)

🔄 TABLE 3 — HIV REPLICATION CYCLE (STEP-BY-STEP)

💊 TABLE 4 — ANTIRETROVIRAL DRUG TARGETS

🔬 TABLE 5 — TRANSMISSION & PATHOGENESIS

🧪 TABLE 6 — LAB DIAGNOSIS (PREGNANCY-FOCUSED)

🤰 TABLE 7 — ANTENATAL MANAGEMENT OF HIV IN PREGNANCY

🚼 TABLE 8 — MODE OF DELIVERY (EXAM GOLD TABLE)

⚠️ TABLE 9 — INTRAPARTUM PRECAUTIONS

👩‍🍼 TABLE 10 — POSTPARTUM (MOTHER)

👶 TABLE 11 — NEONATAL PMTCT MANAGEMENT

🧬 TABLE 12 — EARLY INFANT DIAGNOSIS

🍼 TABLE 13 — BREASTFEEDING & HIV

Common Cancers in HIV — High-Yield Exam Table