Download The human immunodeficiency virus

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HUMAN IMMUNODEFICIENCY VIRUS RNA QUANTITATIVE
Disease overview: The human immunodeficiency virus (HIV) is a lentivirus, a subgroup of retrovirus, that causes HIV
infection and over time acquired immunodeficiency syndrome(AIDS). AIDS is a condition in humans in which
progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive.
Without treatment, average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the
HIV subtype. Human immunodeficiency virus 1 (HIV-1) is thought to have originated as a zoonotic transmission from
simian immunodeficiency virus (SIV)-infected primates, while human immunodeficiency virus 2 (HIV-2) is thought to
have originated as a zoonotic transmission from Sooty Mangabeys. Infection with HIV occurs by the transfer
of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free
virus particles and virus within infected immune cells.
The reverse transcriptase enzyme plays an essential role in the HIV-1 life cycle by converting a single-stranded viral
RNA genome into a double-stranded viral DNA through a complex process known as reverse transcription. The
resulting double-stranded DNA is integrated into the host chromosome to form a provirus. A small proportion of the
viral DNAs form dead-end circular products, which nevertheless can serve as useful surrogate markers for
monitoring viral replication. Utilizing real-time PCR technology, it is possible to track and quantify different stages of
the reverse transcription process, the pro viruses, and the nonintegrated dead-end reverse transcription products.
HIV infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages,
and dendritic cells. HIV infection leads to low levels of CD4+ T cells through a number of mechanisms,
including pyroptosis of abortively infected T cells, apoptosis of uninfected bystander cells, direct viral killing of
infected cells, and killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When
CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes
progressively more susceptible to opportunistic infections.
You can get or transmit HIV only through specific activities. Most commonly, people get or transmit HIV through
sexual behaviors and use of needle or syringe use.
Only certain body fluids—blood, semen, pre-seminal fluid, rectal fluids, vaginal fluids, and breast milk—from a
person who has HIV can transmit HIV. These fluids must come in contact with a mucous membrane or damaged
tissue or be directly injected into the bloodstream (from a needle or syringe) for transmission to occur. Mucous
membranes are found inside the rectum, vagina, penis, and mouth.
HIV is spread mainly by having anal or vaginal sex without using a condom with someone who has HIV or taking
medicines to prevent or treat HIV, sharing needles or syringes, rinse water, or other equipment (works) used to
prepare drugs for injection with someone who has HIV. HIV can live in a used needle up to 42 days depending on
temperature and other factors.
Less commonly, HIV may be spread from mother to child during pregnancy, birth, or breastfeeding. Although the risk
can be high if a mother is living with HIV and not taking medicine, recommendations to test all pregnant women for
HIV and start HIV treatment immediately have lowered the number of babies who are born with HIV.
In extremely rare cases, HIV has been transmitted by oral sex. In general, there’s little to no risk of getting HIV from
oral sex. But transmission of HIV, though extremely rare, is theoretically possible.
Receiving blood transfusions, blood products, or organ/tissue transplants that are contaminated with HIV may also
transmit HIV.
Deep, open-mouth kissing if both partners have sores or bleeding gums and blood from the HIV-positive partner gets
into the bloodstream of the HIV-negative partner. HIV is not spread through saliva.
Having another sexually transmitted disease (STD) can increase the risk of getting or transmitting HIV. If you have
another STD, you’re more likely to get or transmit HIV to others. Some of the most common STDs include gonorrhea,
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chlamydia, syphilis, trichomoniasis, human papillomavirus (HPV), genital herpes, and hepatitis. The only way to know
for sure if you have an STD is to get tested. If you’re sexually active, you and your partners should get tested for STDs
(including HIV if you’re HIV-negative) regularly, even if you don’t have symptoms.
Treatment: No effective cure exists for HIV. But with proper medical care, HIV can be controlled. Treatment for HIV
is called antiretroviral therapy or ART. If taken the right way, every day, ART can dramatically prolong the lives of
many people infected with HIV, keep them healthy, and greatly lower their chance of infecting others. Before the
introduction of ART in the mid-1990s, people with HIV could progress to AIDS (the last stage of HIV infection) in a
few years. Today, someone diagnosed with HIV and treated before the disease is far advanced can live nearly as long
as someone who does not have HIV.
Symptoms Some people may experience a flu-like illness within 2 to 4 weeks after infection (Stage 1 HIV infection).
But some people may not feel sick during this stage. Flu-like symptoms include fever, chills, rash, night sweats,
muscle aches, sore throat, fatigue, swollen lymph nodes, or mouth ulcers. These symptoms can last anywhere from
a few days to several weeks. During this time, HIV infection may not show up on an HIV test, but people who have it
are highly infectious and can spread the infection to others. If you have these symptoms, that doesn’t mean you
have HIV. Each of these symptoms can be caused by other illnesses.
Methodology: RNA quantitation is done using Taqman based Real Time PCR.RNA is isolated from the sample and
reverse transcribed to produce cDNA. Using cDNA as template, specific region of HIV-1(A-H) is amplified along with
standards and quantitated using specific Taqman probe.
Sensitivity: Range for quantitation is 48-10,000,000 Copies/ml (20- 4.2X10^6 IU/ml).
Interpretive DATA: A negative result (less than 48 Copies/ml) does not rule out the presence of PCR inhibitors in the
patient specimen or HIV RNA concentrations below the level of detection by the assay. Inhibition in occasional
patients may also lead to underestimation of viral quantitation.
Note: Although all precautions are taken and results cross checked during Nucleic acid tests, the currently available
data indicates the technical error rate for all such analysis is ~1-2%. The results assume that all the information
regarding the patient and the sample are correct and should be interpreted and acted upon in the light of the
information noted above.
References:
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ARUP Laboratories: http: www.aruplab.com
CDC: www.cdc.gov
NIH: www.nih.gov
Mayo clinic: www.mayoclinic.org
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