Human immunodeficiency virus (HIV)

Sample for Human Immunodeficiency Virus (HIV)

1. For serological tests, the serum is the best sample.
   • These tests can be done on plasma as well.
2. Oral fluids.
3. Urine.
4. Cerebrospinal fluids.
5. Genital secretions.
6. Tears.
7. Breast milk.

Indications of  Human immunodeficiency virus (HIV)

1. These serological tests are done to diagnose HIV infection.
2. For the diagnosis of Acquired Immune Deficiency Syndrome.

Definition of the human immunodeficiency virus (HIV)

• Human immunodeficiency viruses (HIV) are retroviruses; their genetic (genome) information is composed of RNA viruses.
• It is a non-oncogenic retrovirus and is the causative agent of acquired immune deficiency syndrome (AIDS).
• It was first described in 1981, and the virus was isolated by the end of 1983.

Microbiology of Human immunodeficiency virus (HIV)

1. HIV is also called a human T – cell lymphotropic virus.
   1. HIV is also known as the human T- lymphocyte virus (HTLV).
2. This virus measures 80 to 130 nm in diameter.
   1. This is a single-stranded RNA virus, icosahedral and enveloped.
   2. It contains a reverse transcriptase enzyme, which makes RNA into DNA.
   3. This is a member of the retrovirus family.
3. Types of HIV:
   1. HTLV III or LAV (lymphadenopathy-associated virus).
   2. HIV type I. This is common in the USA and western Europe.
   3. HIV type II. This is more common in West African countries.

The difference between the two types is:

Property	HIV I	HIV II
Envelope protein	GP 41 and GP 120	GP 36 and GP 105
Core protein	p 24 and p 18	p 34 and p 68
Spread	Parenteral and sexual	Sexual transmission
The course of the disease	Faster than HIV-1 in developing AIDS	Slow to develop AIDS
ELIZA test	Available	Not available (Western Blot can be used)
Prevalence	Worldwide pandemic	Endemic in West Africa and spread to India

The viral genes are:

1. Gag forms group-specific proteins, antigens, and these proteins are named p24 and p18.
2. Env forms envelope proteins that are necessary for the interaction and presentation of target cells. These are gp120 and gp41.
3. Pol forms polymerase, reverse transcriptase enzymes, and other enzymes like protease and integrase.

The mechanism of injury:

1. HIV has receptors on the CD4⁺ cells, Helper cells, and macrophages.
   1. Virus gp 120 attaches to CD4+ molecules on cells that are present in the lymphocytes.
   2. It is then internalized in the cell with the help of the reverse transcriptase enzyme.
   3. It changes RNA to DNA and integrates with the target cell DNA with the help of viral integrase.
   4. These are known as provirus.
   5. This will enter into the DNA of the host.
   6. Now, this may become latent.
   7. When the virus is assembled and leaves the cells, it buds out, incorporating the host cell membrane into its coat.

2. HIV leads to the destruction  of the host immune system, which can be summarized below:

3. HIV destroys T-lymphocytes, mainly T lymphocytes, which are CD4-positive cells (T-helper cells).
   1. HIV damages the immune system and leads to acquired immune deficiency syndrome (AIDS).
4. HIV infection may be present for as long as 10 years before the patients develop signs and symptoms or become AIDs patients.

HIV infecting other cells on E/M:

Virus buds out of the cells and on electron microscopy show virus bud. This has a double-layer envelope, a dense core, and a less dense intermediate layer.

HIV mode of transmission:

Body fluids with high concentrations of HIV:

1. Blood and contaminated blood products.
2. Semen
3. vaginal fluid
4. breast milk (contaminated).
5. other body fluids containing blood
6. Tears.
7. There is a transplacental spread.
   1. Infants exposed to the virus during gestation or delivery.
8. 2.8% mode of transmission is not known in the USA.
9. 50% are homosexual.
   1. Between men is 60%.
   2. Between men and women, it is 12%.
10. 20% are I/V drug users.
11. 20% are blood transfusions before 1985.
12. 10%  are heterosexual.
13. Roughly 40 million people are living with HIV/AIDS,
    1. 37.1 million adults.
    2. 18.5 million women.

Mode of HIV infection spread:

1. The most common route is sexual:
   1. Oral sex.
   2. Anal sex.
   3. Vaginal sex.
2. Another mode of spread is:
   1. Blood.
   2. Blood products.
   3. Perinatal exposure.
3. In the USA mode of transmission:
   1. Homosexual/Bisexual  50%.
   2. I/V drug users 20%.
   3. Blood transfusion before 1985 was 20%.
   4. Heterosexual 10%.
4. The dose of HIV is not exactly known, but it is estimated that 10 to 100 viruses may cause infection.

High-risk patients are:

1. Homosexuals in males.
2. Bisexual men and women with multiple partners.
3. Intravenous drug abusers.
4. Contaminated blood transfusion.
5. Infants exposed during delivery to positive mothers

The dose of HIV infection:

• Exactly not known, but a rough estimate is 10 to 100 viruses that may lead to infection.

Stages of HIV infection:

HIV causes the disease in three stages:

Stage 1: Acute infection:

1. After 2 to 4 weeks, the infected patients will have early flu-like symptoms.
2. These patients are very contagious. These patients may not come to know that they have an infection.
3. You must advise the fourth-generation antibody/antigen test or nucleic test to diagnose these patients.

Stage 2: HIV inactive or dormant  or clinical latency :

1. This is the stage called asymptomatic HIV infection or chronic infection.
2. This stage may last for a longer period or for decades.
3. These patients may still spread the disease to other people.
4. Now, the CD4+ cell number starts decreasing, and viral loads go up.
5. Patients may start having symptoms, and the viral level is going up, and patients may go into stage III.

Stage 3: Acquired immune deficiency syndrome:

1. This is the most severe phase of HIV infection.
2. The immune system is severely damaged, and these patients are prone to get the opportunity for infection.
3. Without treatment, these patients may live for about 3 years

• CDC revised the Classification based on the number of CD4⁺ lymphocytes. With the decrease in CD4+ cells, the patient will end up with AIDS.

CD4+ cells	CD4+ cells %	Clinical category  A Asymptomatic. Acute HIV, or PGL	Clinical category B Symptomatic Not  A or C Condition like ARC	Clinical category  C AIDS – indicators condition
≥ 500/ mL	> 29%	A1	B1	C1
200 to 400/ mL	14 to 28%	A2	B2	C2
< 200/ mL Aids indicator	>14%	A3	B3	C3

A = ARC (Aids-related complex)

B = Neurological disease.

C 1 = opportunistic infection.

C 2 = Secondary infection like candidiasis and H. Zoster.

A 3, B 3, C 3 = Considered to have AIDS.

Common symptoms of Human Immunodeficiency Virus (HIV) are the following:

1. The incubation period is:
   1. 50% of the cases developing AIDs syndrome takes roughly 10 years.
   2. 20% are symptoms free for more than 10 years.
   3. 20 to 30% show a sign of infection.
2. Initial stage shows:
   1. Headaches, diarrhea, sore throat, myalgia, and arthralgia.
   2. The patients will have weakness and weight loss.
   3. Fever and chills.
   4. Sweating.
   5. There is a macular rash.
3. There are neurologic symptoms.
4. Lymph nodes are swollen (lymphadenopathy).
5. CD4+ cell number drops to <200 cells/cmm.
6. These are highly infectious.

Typical HIV-positive patients (AIDS) show:

1. Fatigue and night sweating.
2. Persistent diarrhea.
3. Weight loss.
4. Frequent infections like Herpes and candidiasis.
5. Candidiasis shows a thrush and vulvovaginal infection.
6. HIV infection may lead to Kaposi’s sarcoma, B- cell lymphoma, and anal carcinoma.

Two or more of the following signs and symptoms are needed to suspect HIV when these are persistent for more than 3 months:

1. Pyrexia is more than 38 °C.
2. History of chronic diarrhea.
3. Weight loss of more than 10%.
4. Mailase and lethargy.
5. Persistent generalized lymphadenopathy (PGL).
6. Night sweating.
7. Oral candidiasis.
8. Hairy leukoplakia.
9. Herpes Zoster infection.

Aids-related diseases:

Etiology	Disease
Tumors	Kaposi’s sarcoma
	Lymphomas
	Cancers
	Cervical cancer
Bacterial infections	Mycobacterium tuberculosis
	Salmonellosis
	Pneumonia
	Atypical mycobacterial infection
Viral diseases	Herpes simplex
	Cytomegaloviral pneumonia
	Cytomegaloviral retinitis
	Encephalopathy
	Dementia
	Diarrhea
Fungal diseases	Candidiasis
	Cryptococcosis
Parasitic diseases	Pneumocystis carinii
	Toxoplasmosis
	Cryptosporidiosis

HIV outside the body:

1. HIV does not survive outside the body, making the possibility of environmental transmission remote.
2. CDC studies have shown that drying even these high concentrations of HIV reduces the amount of infectious virus by 90 to 99% within several hours.
3. HIV is unable to reproduce outside its living host. Therefore, it does not spread or maintain infectiousness outside its host.

Health care worker at risk:

1. Although HIV transmission is possible in healthcare settings, it is extremely rare.
2. Careful practice of infection control procedures is necessary.
3. Protects patients and healthcare providers from possible HIV transmission in medical and dental offices and hospitals.

Diagnostic tests for Human Immunodeficiency Virus (HIV) are the following:

1. Screening test.
2. This test detects antibodies. These are not confirmatory tests. These have to be confirmed by ELISA.
3. These tests are done in blood banking for the screening of donors.
4. This can also be done for the screening of blood products.
5. ELISA
   1. This test is more specific than the screening antibody test.
   2. These tests detect viral antibodies and not antigens.
   3. There is a window period in which the patient will be negative before seroconversion for the test to become positive.
   4. It is used for clinical diagnosis, screening of blood, and blood products. 
   5. This cannot detect HIV infection in the early phase because there is an interval of 2 to 12 weeks, which may even be 6 months.
   6. The person who is infected with HIV becomes seropositive. This time period is called the window period.
   7. This is positive in 99% of the case of patients who have had an infection of HIV for the last 12 weeks or more.
6. Oral fluid for the antibody to HIV is available instead of serum or plasma.
   1. This is a simple, non-invasive, and safe method. 
   2. This is easier for the screening of the population and user-friendly.
   3. This portable method can identify more infected people with the goal of early detection, treatment, and prevention.
   4. This method will decrease the transmission of the disease in the population.
7. Western blot is a confirmatory test.
   1. This test is done to validate the reactive ELIZA.
8. The p24 antigen capture assay may detect the peripheral blood of the patient.
   1. This may be found as an antigen or antibody to p24.
   2. p24 antigen can be used to find the neonatal HIV infection; this detects before there is seroconversion and find the progress of AIDS.
9. HIV in the urine.
   1. This test was approved in 1996 by the USA Food and Drug Administration.
   2. In 1998 license was given for the HIV 1- antibody.
   3. This is useful when there is difficulty with venipuncture.
   4. This is easier, more convenient, safer, and cheaper than the serum test.
10. HIV viral load.

Interpretation of the serologic tests for Human Immunodeficiency Virus (HIV):

1. Serologic antibody test, when positive, should be repeated by the ELISA.
2. When ELISA is positive, confirm by the western blot or by immunofluorescence assay (IFA).
3. Viral RNA may do to confirm HIV.
4. In positive ELISA and negative western blot or IFA, repeat the test after 3 to 6 months.
5. The patient with positive ELISA does not have AIDS until the patients develop signs and symptoms of diminished immunity.
6. Rarely false-positive results may occur.
7. HIV RNA antigens may be detected to confirm the diagnosis.
   1. p24 antigen (protein p24) may be detectable as early as 2 to 4 weeks after infection.
8. Recently oral fluids have been taken to detect antibodies against HIV.
9. Urine may be tested for the HIV antibody.

False-positive tests:

1. These are seen in patients with autoimmune diseases.
2. In patients with:
   1. Lymphoproliferative diseases.
   2. Lymphoma.
   3. Leukemias.
3. In patients with syphilis.

False-negative tests:

1. These are seen in the early stage of infection.
2. Or in the end stage of HIV infection.

Table showing various serological markers (Virus proteins):

Test	Detection	Purpose of the test
ELISA	Ab to HIV	Screening test
Western blot	Ab to HIV	confirmatory test
P24 Ag	HIV-1 core protein	support western blot
Urine for HIV	Ab to HIV	screening test
HIV load	HIV- RNA	marker for diagnosis and AIDS
Home Screening	Ab to HIV	Screening test
oral mucosa sample	Ab to HIV	Screening test

Treatment for Human Immunodeficiency Virus (HIV):

Recommendation for antiviral treatments based on viral load and CD4+ positive cells:

CD4+ count	HIV viral load (copies/mL)	Treatment
<350/cmm	<5000	Treatment recommended
	5000 to 30,000	Treatment recommended
	>30,000	Treatment recommended
350 to 500/cmm	<5000	Consider treatment
	5000 to 30,000	Treatment recommended
	>30,000	Treatment recommended
>500/cmm	<5000	Defer treatment
	5000 to 30,000	Consider treatment
	>30,000	Treatment recommended

1. Antiviral therapy like zidovudine (AZT), Zalcitabine (ddC), and Lamivudine (3TC).
2. Treatment for opportunistic infection is needed.

Prevention for Human Immunodeficiency Virus (HIV):

1. Avoid contact with infected blood.
2. Avoid contact with infected blood products and body secretion.
3. Compulsory screening of the donor’s blood.
4. Educate about safe sex.

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