AIDS/ HIV

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 Introduction:-

AIDS stand for acquired immuno deficiency syndrome. AIDS is a name use to describe the number potentially life threatening infection & illness  that happen when our immune system has been severely damaged by the HIV virus. 
AIDS is a chronic life threatening condition by HIV ( Human Immunodeficiency Virus), were the virus severely damage the immune system by destroying CD-4 + T-cell which are essential for fighting cell. 

Morphology:-

  • HIV is a spherical envelope RNA virus, about 90-120nm. It belong to retro-viridae family also known as retrovirus, specifically latent virus genus. 
  1. The virus is surrounded by a lipid bilayer with viral glycoprotein spikes, gp 120 & gp 41.
  2. gp 120 is surface glycoprotein or gp 41 is transmembrane protein, important for attachment and entry into host cells. 
  3. HIV has a cone shaped core that contains viral RNA neucleocapsid & enzyme. 
  4. The capsid protect the viral RNA and the enzyme that is characteristic feature of retro-viruses. 
  5. The genome of HIV has 2 copies of single stranded positive- sense RNA. 
  6. HIV carries 3 essential enzyme. 
  • Reverse transcriptase converts  viral RNA into DNA. 
  • Integrase:- this enzyme integrates viral DNA into the host genome. 
  • Protease:- this enzyme process viral proteins during maturation. 

Pathogenesis:-

  1. Entry :- an infectious HIV enters the body through blood product organ transplantation, sexual contact, secretion of reproductive system mother to child (passive transmission), contaminated needles. The virus binds to the CD4+ T cells and also macrophage and dendritic cells. 
  2. Viral Replication:- After the entry of HIV reverse transcriptase enzyme convert it's RNA into DNA, which is integrated into the host genome by integrase. The host cell machinary produces new viral RNA & protein assembly them into new virions ( virus particle).
  3. Immune activation and cell death:- HIV Replication activated the immune system leading to chronic inflammation infected CD4+T cells are killed by direct viral effects, immune mediated destruction or apoptosis ( programmed cell death).
  4. Immune system decline:- over time CD4+ T cells gradually decline impairing the immune system. The body becomes spectacle to opportunistic infection & cancers the cellular immunity is cheaply damage while numeral mechanism are also affected as a result AIDS patients are unable to new antigen.

Clinical symptoms:-

  • Within the few weeks of HIV infection flue like symptom such as fever, sore throat and fatigue can occur.
  • The disease is usually asymptomatic until it's progresses to AIDS 
  • Asymptomatic or latent infection- all persons infected with HIV may pass through a phage of symptom less infection known as clinical latency, which may last upto several years, these person are positive for HIV antibodies and are infectious at the same time.
  • The period between the primary HIV infection and the development of AIDS it's said to be approximately to years in this period virus multiplication goes on.
AIDS related complex:- the symptoms are fatigue, fever, persistent diarrhea, weight loss etc.
AIDS:- this is the end stage of disease representing irreversible break down of immune defence mechanism living the patient open the progressive opportunities and resulting in death in years.

Lab diagnosis:-

  1. Antigen detection:- the antigen is detected in the blood. The core antigen p24 is the earliest virus marker to appear in blood.                                            The p24 can also be detected by ELISA. The patient serum when taken, there is an appearance of IgM antibody.    
  2. Detection of viral nucleic acid:- the amplification of viral DNA, RNA is most sensitive and method for the detection of HIV.                                                    These nucleic acid can be detected by (1) DNA PCR- the test can detect pro viral DNA.                                                  (2) Rt pcr- reverse transcriptase PCR.      This is a useful test to detect disease progression and monitor response to therapy.
  3. Antibody detection:- the demonstration of antibodies is the simplest and most widely employed technique for the diagnostic of HIV infection.                        However, it may take 2-8 weeks to two months for antibodies to appear in the patient serum.                                              This siro negative infective stage is known as the the window period.            The IgM antibodies  appears in weeks followed by IGg. Prior to IgM and IGg antibodies to p24 antigen is detected.
  4. Test used for screening:-  ELISA, rapid test using blood, urine, saliva, western blot test, sputum, etc.
  5. Virus isolation:- cultivated in animal tissue and Pro ELISA.   

Prevention:-

  • Till date no safe and effective vaccine against HIV virus has released.
  • While taking precautions during blood transformation, safe sex, infected needle.

Treatment:-

  • Anti retro- viral drug includes nucleoside analogies like Zidovudin        ( azido thymedin ), Lamibudine, didanosine and protease, inhibitors like rito, ritonavir indinavir.
  • Highly active anti retro- viral treatment (HAAT).

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