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Retroviruses are characterized by producing
enzymes reverse transcriptase.
Therefore, viral RNA can be converted into DNA.
This DNA incorporates into the host genome and
produces progony viruses
In this period the infected viruses do not produce
sings or symptoms.
It is named as LATENT PERIOD.
The long & variable incubation period of HIV
infection is because of the latency.
Viral RNA ------> DNA -------> integrated with Host cell genome -------> Release progony virus
<------------------------------------------ Latent period------------------------------------------------>
Two types:
1) Cellular immunity
2) Humoral immunity
| T Cells produce -------> | a) Cytotoxic cells-------------> b) Suppressor cells (T8)-----> c) Helper cells (T4)----------> | CELLULAR IMMUNITY |
|---|
| B Cells produce -------> | Immunoglobulins -------------> a) IgG b) IgA c) IgM d) IgD e) IgE | HUMORAL IMMUNITY |
|---|
T cells produce cellular immunity
B cells produce humoral immunity
T4 lymphocytes help to proliferate immunoglobulings.
Therefore T4 cells also regulate humoral immunity.
Both of these immune systems protect the body against the infection.
The virus attacks T4 lymphocytes.
Therefore T4 lymphocytes,
a) DamageBecause of this,
b) Decrease in number
T4 ( Helper cells)
------------------------
T8 ( Suppressor )= Ratio reversed
c) Function is suppressed
Because of this,
Interleukin
Gamma interferon
Lymphokinase} secretion decrease
An important feature is the polyclonal activation of B lymphocytes that leads to hypergammaglobulinemia. All classes of immunoglobulins are involved and particularly IgG & IgA are raised.
This hypergammaglobulinaemia is more hindrance than help because it is mainly composed of USELESS IMMUNOGLOBULINS.
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