April 27, 2021 | Written By: Mohd Syafiq
What is HIV Virus?
HIV (Human Immunodeficiency Virus) is a type of virus that attacks the body's immune system which weakens the body's ability to fight infection and disease. The virus attacks the body's defence system especially CD4 cells (T cells), a type of cell that is important to help the body fight infection.
When infected with HIV, the number of CD4 cells (T cells) in the body decreases and at the same time makes a person more vulnerable to infection or cancer if left untreated. HIV can destroy so many of these cells that the body’s immune system paralysed. This is the last stage of HIV infection known as AIDS.
For normal and healthy humans, they will usually have CD4 cells between 500-1500 cubic millimetres. Once the HIV attacks CD4 cells, those cells will shrink and the body's immune system weakened. An individual is classified as having AIDS if the CD4 cell count is below 200.
Virus HIV is a retrovirus that comes from the family Retroviridae, genus Lentivirus. The human body cannot get rid of HIV completely even with treatment. Therefore, those infected with HIV will live forever with HIV.
There are two types of HIV:
Most cases of HIV are caused by HIV-1. The differences between these two types of viruses are basically in terms of genetics apart from a few other differences such as:
HIV Infection is found widely around the world. It is said that almost 95% of HIV-positive people are infected with the HIV-1 virus. While HIV-2 has a lower infection rate and is rarely found.
Both types of virus have the same way of spreading, that is through fluids from the body that contain the virus such as blood and semen. However, the spread of HIV-1 is easier than that of HIV-2.
Studies are showing HIV-2 is more often spread through heterosexual sexual intercourse. But, its transmission rate is 5-10 times lower than HIV-1. Transmission of HIV-2 from mother to fetus is also lower.
3) Development of Infection
A person infected with HIV-1 is more likely to develop a serious infection and degenerate into AIDS. Meanwhile, for individuals infected with HIV-2, this group may not be affected by AIDS during HIV-2 exposure. However, if AIDS occurs, it may take longer than HIV-1.
HIV-1 infection generally has a higher viral load than HIV-2. Viral load is the amount of virus detected in the blood. Furthermore, the CD4 count for HIV-1 infection is usually lower than in HIV-2 throughout the infection.
How the HIV Virus Infects the Human Body
HIV attaches and penetrates T cells through CD4 molecules and receptors chemokine. Thereafter, HIV RNA and some encoded HIV enzymes are released into the host cell.
Viral replication requires reverse transcription (RNA -dependent DNA polymerase) copying HIV RNA, producing proviral DNA; this copying mechanism is prone to error, resulting in frequent mutations and thus resulting in new viral variants. These mutations produce viruses that can overcome control by the body’s immune system and antiretroviral drugs.
Proviral DNA enters the nucleus of the host cell and is incorporated into the host DNA in a process that involves integration with other HIV enzymes. With each cell division, the integrated proviral DNA is duplicated along with the host DNA. Subsequently, proviral viral DNA can be transcribed into HIV RNA and translated into HIV proteins such as glycoproteins 41 and 120. These HIV proteins are synthesized into HIV virions on host inner membrane cells and grow from the cell surface in modified human cell membranes. Each host cell can produce thousands of virions.
Once evolved, proteases, other HIV enzymes and viral proteins that have been divided, will transform immature virions into mature and infectious virions. Infected CD4 lymphocytes produce more than 98% of the plasma HIV. A small number of infected CD4 lymphocytes are a reservoir of HIV that can be reactivated.
In moderate to severe HIV infection, about 108 to 109 virions are created and released each day. The average half-life of HIV in plasma is around 36 hours. About 5 to 7% of CD4 cells change every day, and the whole group of CD4 cells change every 2 days. Thus, AIDS stems from the continuous and consistent replication of HIV, which leads to virus and CD4 lymphocyte killing. Furthermore, the high number of HIV replication and the high frequency of transcription errors by HIV reverse transcription result in many mutations, increasing the chances of producing immune and drug-resistant strains or variants
Initially, HIV was found in chimpanzees in Africa and infection occurs only among chimpanzees. However, after several studies, it was found that HIV has mutated and can infect humans. After that, HIV began to spread around the world among humans.
Why this infection feared by many is not only because it is deadly but until now no cure has been found to cure or destroy this virus from the human body completely. Besides, the symptoms of this infection are similar to the symptoms of other diseases which makes it difficult to detect at an early stage.
The most common early-stage symptom of HIV is swelling of the glands.
HIV In Malaysia
HIV was first reported in Malaysia in 1986 with three cases and this number continues to increase every year. In 2002, a total of 6,978 cases appeared, resulting in various programs and initiatives undertaken by the government and non -governmental organizations (NGOs) to address the problem of virus transmission.
In 2018, the number of HIV cases decreased to 3,293 cases. However, the Malaysian Ministry of Health (MOH) and the World Health Organization (WHO) have set a target of zero new cases by 2030.
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