Serodiagnosis Of Hiv ClinPath Midterms PDF

FIRST SEMESTER: CLINICAL PATHOLOGY MIDTERMS SERODIAGNOSIS OF HIV #03 Johari M. Ancheta, MD, DPCP...

FIRST SEMESTER: CLINICAL PATHOLOGY MIDTERMS SERODIAGNOSIS OF HIV #03 Johari M. Ancheta, MD, DPCP OCT - 13 - 2023 OUTLINE I HIV Epidemiology II. CHARACTERISTICS OF HIV Characteristics of HIV Genus: Lentiviridae A. HIV Transmission → which means this virus causes chronic, deadly disease II B. HIV Replication and involves lengthy incubation time C. Stages of HIV infection → category of viruses that only infect cells with CD4+ D. Diagnostic definition expressed in the cell membrane Laboratory Testing Family: Retroviridaae A. CD4 T Cell Enumeration Common name: Retrovirus B. Antibody detection Single-stranded, positive sense, RNA genome III C. Antigen detection Unique enzyme: Reverse transcriptase → converts D. Viral nucleic acid genomic RNA into DNA E. Viral culture Two genetically different but related forms of HIV, mainly F. Testing algorithms HIV-1 and HIV-2 have been isolated from patients with AIDS. I. HIV EPIDEMIOLOGY The HIV-1 variant is the most prevalent type globally → highly infective and highly virulent Most common mode of transmission is through sexual HIV 2 has low infectivity and virulence rate and restricted contact where higher risks is associated through male to only to Africa male sex A zoonotic disease (mainly primates as primary hosts) as Affects numerous countries worldwide: it crosses the species barrier ▪ Total → 35.0 million in 2013 ▪ Sub-Saharan Africa → most affected (23.1 million – Table 1. Comparison of HIV species 26.1 million cases) Species HIV-1 HIV-2 ▪ Asia and the Pacific → second affected (4.8 million cases) Virulence HIGH LOW ▪ Today, affected individuals are around 25 million Infectivity HIGH LOW Local data (Philippines) based on DOH statistics Prevalence Global West Africa → Total reported cases → 68,401 (from 1984-2019) Inferred origin Common chimpanzee Sooty Mangabey → Reported deaths → 3,459 → Mostly affected are males as based in the demographic Table 2. HIV structure data majority ranging from 25-34 years old HIV-1 virion is spherical, composed of electron-dense, → In pregnant women although minimal, eventually their cone-shaped core enclosed by a lipid envelope derived from child can be infected by the HIV as soon as they were born host cell membrane Genes TAT gene essential to → “transactive transcription” enhances the viral transcription and thus the expression of viral replication proteins by binding to the TAR (transactivation responsive region) in the LTR REV gene → post transcriptional activator for splicing and transport of viral mRNA (production of structural proteins) LTR sequence → promoter and enhancer elements Structural gag gene genes → group-specific antigen pol gene → codes for the reverse transcriptase, a protease and integrase env gene → envelope glycoprotein (gp) Genes not Virus infection factor (vif) essential to → makes the virus more infectious viral replication Negative factor (nef) (not essential → inhibits or activates viral transcription as but enhance required, influences t cell activation, reduces the capacity of CD4 expression virus to survive) vpr → controls rate of replication (TWG) TAPIT, TE, TAGANAS | (TEG) | (TC) COSTALES NMD2026  Lesson 3: Serodiagnosis of HIV NMD2026 A. HIV TRANSMISSION vpx → only in HIV 2, controls rate of replication Can be transmitted from one person to another by the ff: vpu 1. Intimate sexual contact → only in HIV 1, contributes to viral release, → 85% are through heterosexual contact (worldwide) increases CD4 turnover → STIs increase likelihood of transmission especially if there are lesions in the genitals during the sexual activity 2. Contact with blood or other body fluids → Sharing of contaminated needles (recreational use of the needles ; in healthcare it is only used once) → Average risk of transmission to health workers ★ 0.3% - percutaneous exposure (accidental prick from a needle) ★ 0.09% - mucous membrane exposure 3. Perinatally, from infected mother to infant (vertical transmission) According to doc, studies have reported that you need to at least drink up to 9 galloons of saliva to get infected with the HIV (oh noe mah men!) Table 3. HIV Transmission POTENTIALLY BY NOT INFECTIOUS INFECTIOUS BODY FLUIDS Blood Saliva Semen Sputum Vaginal secretions Nasal secretions CSF Tears Synovial fluid Sweat Pleural fluid Urine Vomitus Feces B. HIV REPLICATION 1. Binding and fusion 2. Reverse transcription 3. Integration 4. Transcription 5. Assembly 6. Budding 1. BINDING gp120 (HIV) binds to the CD4 T cells (T tropic/X4 strains); other cells (M tropic/R5 strains): macrophages, monocytes, dendritic cells, langerhans cells and microglial cells 2. FUSION Requires chemokine receptors → CXCR4 - T-cells → CCR5 - macrophages Induce conformational change in the gp41 Happens when chemokine receptor binds to gp120 and gp41 3. REVERSE TRANSCRIPTION HIV capsid → bullet shaped core that contains HIV Viral contents now gains entry into the host membrane RNA Releases the nucleic acid material within the capsid and HIV envelope → Outer surface of HIV the enzymes HIV enzymes → Proteins that carry out steps in the HIV RNA unravels followed by reverse transcription HIV life cycle Enzyme reverse transcriptase produces complementary HIV glycoproteins → protein “spikes” embedded in DNA from the viral RNA the HIV envelope HIV RNA → HIV’s genetic material 4. INTEGRATION p24 capsid → protein that makes up the nucleocapsid material The cDNA crosses the nuclear membrane along with gp41 → stalk of the spike enzyme integrase gp120 → head of the spike Integrase cuts a nick into the host’s genome and inserts that cDNA into the host genome itself Viral DNA becomes integrated into the host cell’s genome and is called a PROVIRUS 2 of 10  Lesson 3: Serodiagnosis of HIV NMD2026 5. REPLICATION Under favorable conditions, if there is activation of the portion where the provirus is inserted, it is subjected to central dogma (replication, transcription, translation) make long chains of HIV proteins 6. ASSEMBLY The virus can only start assembling itself once it completes the (3) central dogma processes In most cases it does not occur right away. The reason for long incubation periods of the virus HIV proteins move to the surface as immature (non infectious) HIV Autoassembly Once products are produced, accumulate under the cell membrane of the host cell and automatically group themselves in a process termed AUTO ASSEMBLY 7. BUDDING Immature HIV pushes out of the host cell Protease breaks put the long protein chains to form Figure 2. Life cycle of HIV mature (infectious) HIV When a virion buds off it takes a portion of the host’s cell C. STAGES OF HIV INFECTION membrane → results in the deficiency of the cell membrane → cell lysis → damages/kills the host cells Three stages of HIV infection: Remember that HIV causes much decreases in your Acute infection stage/primary HIV infection CD4+ T helper cells Clinical latency stage/chronic HIV infection AIDS Note: see diagram below to visualize process Table 4. Stages of HIV infection Stage 1: Acute Flu like symptoms: infection stage or → fever primary infection → swollen glands → sore throat → rash → muscle and joint pains → fatigue → headache Stage 2: Clinical Asymptomatic HIV infection latency stage or Chronic HIV infection Stage 3: AIDS → CD4+ cells falls below 200 (terminal stage) cells/mm3 → RNA copies rises → develop one or more opportunistic illnesses, regardless of your CD4 count (AIDS defining disease) Figure 1. HIV Life Cycle; familiarize this diagram Blue lines represent CD4+ count Red Lines represent HIV copies 3 of 10  Lesson 3: Serodiagnosis of HIV NMD2026 ▪ Signals are interpreted by the machine D. DIAGNOSTIC DEFINITION → Removing the erythrocytes by lysis Diagnostic definitions of AIDS in adults → Stabilizing the leukocytes by fixation with Serves as clinical diagnosis paraformaldehyde → Normal: 600–1200 cells/uL Table 5. Categories of AIDS CD4+ T cells/ul Clinical Categories A B C >500 A1 B1 C1 200-499 A2 B2 C2