Materials: HIV/AIDS Diagnostics

HIV- infection diagnostics

HIV- infection diagnostics includes 2 stages: determination of personal fact of HIV contamination and determination of disease stage

90-95 % contaminated, antibodies to HIV appear during 3 months after the contamination, 5-9 % after 6 months and 0.5-1 % - in later period. The most precautious period of revelation of antibodies is 2 weeks after the moment of contamination.

In principle, antibodies detection can reveal more than 99 % of infected people. Some difficulties are connected with that the antibodies to HIV are lack in the early weeks after the contamination, but in terminal stage of disease their quantity can be reduced noticeable.

Most often the antibodies to HIV are detecting by immune enzymatic methods.

A special assay kit is called the Diagnostic test-systems for the revelation of markers of HIV infection. There are no principal differences in numerous commercial test-systems for solid phase IFA, though they can be differed substantially on sensibility and specificity. Fairly often happens that the same serums produce different results when using different test-systems. In connection with this it is admitted that the positive result of researches should not be considered unconditionally as a positive result.

Series of methods are proposed for checking of results specificity of antibodies detection.

Most often the reaction of immune blotting is applied among these methods. The content of immune blotting method lies in that the immune enzymatic reaction is conducted not with the mixture of antigens, but with the HIV antigens, preliminary distributed method of immune pharoses on fractions, located as consisted with the molecular mass on surface of the nitrocellulose membrane. Consequently basic proteins of HIV are spreading on the surface in the form of separate lines, which are showing up during the conduction of immune enzymatic reaction.

Detection of antibodies to HIV includes 2 stages. On the first stage detection of summery spectrum of antibodies to HIV is conducting with the usage of different tests, usually of immune enzymatic. On the second stage determination of antibodies to separate proteins of virus is conducting by the method of immune blotting.

The methods of virus detection are used, with the aim of diagnostics, its antigens and gene material (peculiar nucleotide consequences).

Most often among the antigens of HIV they attempt to detect the p24 HIV-1, however this method was not been widely used in epidemiological researches, as the greater part of antigen is not connected with the antibodies only in the early period of disease and in the development period of clinically apparent immunodeficiency. In connection with this method is of interest for patients detection on the early stages of HIV infection and sometimes for the estimation of disease progressing. Detection of this antigen in the child, born from HIV infected mother may serve as a criterion during diagnosing in him the HIV-infection.

Discharge and identification of HIV culture is a significant sign of HIV infection, however this method inaccessible, it demands a long period, high qualification of performers and special equipment.

At last, method of HIV gene material detection by the methods of replication (amplification, reproduction) of specific gene sequences often joined under the name of one of this method variants- “polymerase chain reaction”. Advantage of PCR is its ability to detect HIV-infection in incubatory and in the early clinical periods, when the antibodies may be absent. Reactions like PCR are successfully used for prognostication of disease course and estimation of the therapy efficiency, determination of quantitative indices of HIV presence in biological fluid.