HIV infection

Which specific surface receptors of target cells do the proteins of the immunodeficiency virus bind to?

The immunodeficiency virus protein binds to the specific CD4 receptor as well as chemokine co-receptors on the membrane of target cells. Initial binding is performed by the surface viral glycoprotein gp120 with the CD4 receptor (on T-lymphocytes, monocytes, and macrophages). Subsequent entry of the virus into the cell strictly requires co-reception with chemokine receptors:

• CCR5 — predominantly at early stages of the disease (on macrophages).
• CXCR4 — during further disease progression (on the surface of T-cells).

Which viral enzyme ensures the synthesis of viral DNA after entering the host cell?

The synthesis of viral DNA after HIV enters the host cell is mediated by a specific enzyme, reverse transcriptase (revertase). This viral enzyme performs the process of reverse transcription—the synthesis of a complementary DNA strand using the viral genomic RNA template as a blueprint. Following the formation of the double-stranded DNA transcript, the resulting proviral DNA integrates into the cell's chromosome, which is necessary for subsequent viral replication.

What stages of the clinical course of HIV infection are distinguished in modern classification?

In modern Russian clinical classification (according to V.I. Pokrovsky), five sequential stages of HIV infection are distinguished:

• Stage 1 — incubation stage.
• Stage 2 — stage of primary manifestations (includes the asymptomatic phase, acute infection without secondary diseases, and acute infection with secondary diseases).
• Stage 3 — subclinical stage.
• Stage 4 — stage of secondary diseases (subdivided into 4A, 4B, 4C depending on the severity of opportunistic lesions).
• Stage 5 — terminal stage.

Which specific opportunistic diseases are characteristic of the terminal stage (AIDS)?

In the sources, a specific list is provided for stage 4B—the stage of secondary HIV infections. The following are indicated:

• generalized bacterial, viral, fungal, protozoal, and parasitic diseases;
• lesions of the esophagus, bronchi, and lungs of fungal, herpesvirus, or CMV etiology;
• atypical mycobacteriosis;
• disseminated Kaposi's sarcoma;
• central nervous system lesions;
• cachexia.

Separately for CMV infection, it is indicated: CMV organ involvement, other than or in addition to the liver, spleen, and lymph nodes, in a patient older than 1 month is included in the list of AIDS-defining conditions.

According to ICD-10, HIV infection resulting in infectious and parasitic diseases and HIV infection resulting in malignant neoplasms, including Kaposi's sarcoma, Burkitt's lymphoma, and other non-Hodgkin lymphomas, are also distinguished.