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HIV-1

General aspects
HIV 1 infection

Fig.1 -Scheme of HIV-1 infection

The human immunodeficiency virus (HIV) is responsible of the Acquired Immune Deficiency Syndrome (AIDS). The HIV is divided in two family: HIV-1 located mainly in Europe, America,
Asia and central Africa and HIV-2 is instead in West Africa where it causes a sindrome clinically more moderate then HIV-1. The HIV is a retrovirus (RNA virus) member of lentivirus characterized by a very long incubation time. The HIV-1 genome is variable so it’s usual to classify it into three groups: M (major) group, divided in 12 subtypes (A,B,C,D,F,G,H,J,K,AB,AE,AG); N group and O group. The virus has a sexual transmission (vaginal secretions, semen, blood), vertical blood transmission through blood contact and/or infected blood products, from mother to child during pregnancy, childbirth or breastfeeding.
After infection, the virus coming in the bloodstream, attacks the CD4 + T lymphocytes, immune system cells to replicate himself. Once inside, the viral RNA is modified into the DNA to integrate genome (provirus) into the host cell. HIV can remain inactive within the cells or begins a replicative process to form new viral particles; these are excreted from the cell, causing the cell demolition, and released into the bloodstream, ready to infect new cells CD4 + T. Acute infection lasts 1-2 weeks and it generally has not so specific clinical conditions , flu-like. At the end of the acute phase the symptoms disappear and it starts the slow immune response of the body, that it lasts 2-8 weeks, with the production of antibodies (HIV-positive).
In absence of treatment, the latency phase (or chronic) can last for many years and although the clinical condition of the HIV positive patient are stable, the lymphatic system suffers a progressive deterioration, because of the viral replication continues and the destroyed CD4+ T cells are not replaced. When their number falls below the critical threshold (200/ml) the body isn’t able to defend themselves from "opportunistic infections", caused by normally poorly pathogenetic microorganisms (bacteria, fungi, viruses, protozoa), that in low levels of CD4+ T lymphocytes, can cause pulmonary, gastro-intestinal, ocular and cerebral diseases with serious clinical conditions (AIDS). Currently, the treatment is based on anti-retroviral drugs that not allow to delete the virus but limit the proliferation and reduces the CD4+ T cells destruction.

Molecular test

In Tecnobios Prenatal Eurogenlab is available a molecular tests (HIV-1 Viral Load) to evaluate of the viral load, expressed in copies/ml in plasma. The sensitive and accurate test allows to detect the presence of viral RNA, of all subtypes of HIV-1, until to 20 copies/ml and quantification in a wide range of linearity (40-10,000,000 copies/ml). The molecular test HIV-1 is suggested mainly for the control of male and female gametes donors, stem cells donors, but also for to the advance of "coverage" of the window period after exposure to the virus detected or for monitoring the effectiveness of antiviral drugs.

Response times

The test result is available after 3 hours from the draw blood.


Analyzed material

RNA extracted from plasma isolated from peripheral blood collected in EDTA tubes.

References
Katzenstein DA, et al. The relation of virologic and immunologic markers to clinical outcomes after nucleoside therapy in HIV-infected adults with 200 to 500 CD4 cells per cubic millimeter. AIDS Clinical Trials Group Study 175 Virology Study Team. N Engl J Med. 1996

Mellors JW, et al. Plasma viral load and CD4+ lymphocytes as prognostic markers of HIV-1 infection. Ann Intern Med. 1997

Mellors JW, et al. Prognosis in HIV-1 infection predicted by the quantity of virus in plasma. Science. 1996

O’Brien WA, et al Changes in plasma HIV-1 RNA and CD4+ lymphocyte counts and the risk of progression to AIDS. Veterans Affairs Cooperative Study Group on AIDS. N Engl J Med. 1996

Ruiz L, et al. Quantitative HIV-1 RNA as a marker of clinical stability and survival in a cohort of 302 patients with a mean CD4 cell count of 300 x 10(6)/l. Aids. 1996

Saag MS, et al. HIV viral load markers in clinical practice. Nat Med. 1996