Blood Borne Viruses Flashcards by Rebekah Agunede

Conditions associated with HIV later stage

Oral candidiasis 
Kaposis sarcoma (rash)
Pneumocystis pneumonia (PCP)

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Pathogen complications HIV

Reactivation of virus (those that lie dormant and then reappears (latent)

Fungus (yeast, mould) common

Protozoa common

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Outcomes for HIV

Chronic infection +/- disability
Death
Management

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Structure virus

Genome (RNA vs DNA) double/signle strand

Capsid (protein shell) - helical vs icsohedral

Lipid envelope (derived from host cell membrane) present/absent

Replication strategy

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HIV virus type

Retrovirus - inserts RNA into host cell, uses reverse transcriptase to convert it to DNA, converts back

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Genetic material HIV

Single stranded RNA

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How does HIV infect?

Gp120 (glycoprotein on HIV) infects cells that have CD4 surface receptor

(Mostly T helper lymphocytes)

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Cells with CD4 receptor

T helper lymphocytes

Monocytes/macrophages

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What does HIV do once inside cell?

Replicates:
Destroys cell
Causes inflammation
Spreads to/infects more cells

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Enzymes important in HIV

Reverse transcriptase - ssRNA converted to dsDNA

Integrase - Viral DNA intergrated into host cells DNA

Protease - new viral particles cut to combine to form new activated virus

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Receptors HIV binds to

CD4
CCR5
CXCR4

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Transmission of HIV

Sexual contact

Transfusion

Contaminated needles

Perinatal (usually during delivery through infected birth canal or through breast milk)

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Stages of HIV infection

Primary infection (seroconversion)

Latent infection

Symptomatic

Severe infection/AIDS

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Primary infection

Flu like symptoms (CD4 low)

Viral load high - infectious

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Latent infection

Viral load lowers
CD4 count recovers

Dormant virus

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Symptomatic infection

CD4 count below 350

Viral load increasing

Severe infection/AIDS

CD4 count below 200 cells per microlitre

Viral load very high

Symptoms of HIV

Malaise
Headache
Rash
Nausea/vomitting
Enlarged spleen
Mouth sores/thrush
Fever
Weight loss

Factors affecting HIV transmission

Tye of exposure
Viral load in blood
Condom use
Breaks in skin/mucosa (from other STI’s/sexual assault)

Highest risk of transmission from exposures

Transfusion (very high risk)
Anal intercourse (receptive) (1.1%)
Injection (1/149)

Living with HIV now

Life expectancy and quality of life very good

80 years

Factors affecting life expectancy with HIV

Early detection (good starting CD4 levels)
Treatment
Adherence
Healthy habits (no smoking, limit alcohol, exercise)

HIV tests

Blood test - serology (test for antigen and antibody) - falso negative possible

PCR - highly sensitive (used for follow up not initial as expensive)

Rapid at home tests - low cost (finger prick, oral) false positives - confirm with serology

Who should be tested?

Everyone
Resp: bacterial pneumonia/TB
Neuro: meningitis/dementia/neurotoxoplasmosis
Derm: severe psoriasis 
Gastro: chronic diarrhoea/weight loss
Haem: anaemia with no cause?
Onc: lymphoma, anal cancer
Gynae: cervical intraepithelial neoplasia
ANY STI, HEPB, HEPC

Treatment HIV

Anti-retroviral drugs

Aims of HV treatment

Undetectable viral load = 0 risk of transmission Restablish CD4 and immune system Reduce systemic inflammation Normal lifespan/quality of life

Drug targets HIV

Attachment Reverse transcriptase inhibitors Protease inhibitors Integrase inhibitors

When to start HIV treatment?

CD4 <350 | As early as possible

Anti retrovirals classes

Nucleoside reverse transcriptase inhibitor AND - non nucleoside reverse transcriptase inhibitor OR - Protease inhibitor OR - Integrase inhibitor OR - CCR5 (entry) inhibitor

Why do HIV patients need more than 1 ARV?

Virus mutates Resistance to drug develops 2-3 drugs = harder to develop resistance

Strategies to reduce HIV prevalance

``` Condom use ARV prevention treatment Testing/screening Post exposure prophlaxis Male circumcision (voluntary) ```

New HIV treatments

Pre exposure prophlaxis (if dont have HIV but at risk) Dual therapy Injectable drugs (every 2 months instead of daily) Monoclonal antibodies (Ibaluzimab attachment inhibitor) VACCINE??

Ethical dilemmmas HIV

Psychological impact of diagnosis Stigma Patient confidentiality vs health of others

Blood borne viruses examples

HIV Hep B Hep C

Neurological problems associated with HIV

Neurotoxoplasmosis - parasite in brain