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The Virus 


AIDS is caused by a member of the lentivirus family, human immuno-deficiency virus (HIV). Lentiviruses are characterized by a single stranded RNA genome and RNA dependent DNA polymerase (reverse transcriptase) carried in infectious virions. HIV preferentially replicates in cells of the immune system, CD4+ lymphocytes, leading to CD4+ lymphocyte depletion. HIV replicates continuously in vivo at very high rates and replication of the viral genome is highly error prone.

Hepatitis B Virus (HBV)


There are at least five major hepatitis viruses, three of which can cause persistent infection and chronic hepatitis: the hepatitis B virus (HBV), the hepatitis C virus (HCV), and the hepatitis D virus. HBV possesses a double stranded circular DNA genome, whereas the others are single stranded RNA viruses. HBV is a spherical particle consisting of a core particle enveloped by a surface coat that contains the surface antigen (HBsAg). Failure to clear HBsAg from the blood is the hallmark of chronic HBV infection.

Epidemiology of Hepatitis B 


Hepatitis B Virus (HBV) remains a significant global health concern, with approximately 300 million individuals infected worldwide. HBV is a leading cause of liver-related health conditions, including liver cancer. The highest prevalence of chronic HBV infection is in Asia, where more than 75% of chronic carriers are located. In the United States, it is estimated that between 200,000 and 300,000 people are newly infected with HBV annually. Chronic infection occurs in approximately 10% of those infected. The Centers for Disease Control (CDC) estimates that 1 to 1.25 million people in the U.S. live with chronic HBV.


Three primary mechanisms of transmission for HBV are:


  • Mother to infant
  • Person to person
  • Parenteral (bloodborne)

Infection during infancy or early childhood carries the highest risk of developing chronic infection. The likelihood of chronic infection is greatest during the perinatal period, with a rate of 70-90%, and decreases to 6-10% by the age of six years.


Hepatitis C Virus (HCV)


Hepatitis C virus (HCV) is an RNA virus from the flavivirus and pestivirus families. Its complete genome has been sequenced using molecular techniques, and the virus particles have been observed in recent studies.


HCV is known for its high mutation rate, meaning that individuals infected with the virus have multiple closely related viral variants, referred to as quasispecies. This variability in the virus allows it to adapt quickly to changes in its environment, which can make it more difficult to target effectively.


The presence of quasispecies in an infected person means that the virus population is diverse and can behave differently in various conditions, which can impact the effectiveness of any treatment or management strategy.

Epidemiology of Hepatitis C


Hepatitis C is a widespread condition, with approximately four million individuals affected in the United States alone. It is associated with significant liver complications, contributing to a large number of deaths annually, primarily due to liver-related issues. The progression of the disease is complex and varies, with only a portion of those infected developing severe liver damage. However, predicting who will experience significant progression remains a challenge. Data from tertiary centers indicate that a significant proportion of individuals present with chronic hepatitis, cirrhosis, or hepatocellular carcinoma, with a subset developing these complications several years after initial evaluation.


=> This video offers a detailed examination of HIV virus behavior and its interaction with the immune system, focusing on key scientific insights into disease progression :