The Battle Between Vaccines and Natural Infection: How Our Bodies Remember Hepatitis E

Hepatitis E is a liver infection that can be quite serious. It is caused by a virus. The body's immune system plays a big role in fighting it off. The immune system has a memory. It remembers how to fight off infections it has seen before. This memory is crucial for preventing future infections. A recent study looked at how the immune system remembers hepatitis E. It compared natural infection with vaccination. The study took place in a nursing home. An outbreak of hepatitis E occurred there between June and August 2023. The study involved 60 people who had been infected with the virus. It also included 58 people who had been vaccinated against it. Four people who had not been infected or vaccinated served as controls. Researchers used several methods to study the immune response. These included multicolor flow cytometry, ELISA, and quantitative polymerase chain reaction (qPCR). These tools helped detect memory T-cell expression profiles, HEV-specific antibodies and cytokine expression. The study found some interesting things. First, it looked at the levels of HEV-specific IgM. This is a type of antibody. It is produced during an active infection. The levels of HEV-specific IgM were higher in patients with acute jaundiced hepatitis E. These are patients who had severe symptoms. The levels were lower in patients who did not have jaundice. This suggests that the severity of the infection affects the production of this antibody. However, the levels of HEV-specific IgG were not affected by the severity of the infection. This type of antibody is produced later. It provides long-term protection. The study also looked at memory T cells. These are a type of white blood cell. They help the immune system remember how to fight off infections. The percentage of CD8+ TEM cells was higher in people who had recovered from the infection. This was true even six months after recovery. This suggests that the immune system's memory improves over time. The study also compared natural infection with vaccination. It found that vaccination increased the levels of HEV-specific IgG. This is the antibody that provides long-term protection. Vaccination also increased the levels of certain cytokines. These are proteins that help regulate the immune response. The cytokines IL-7 and IL-15 were higher in vaccinated individuals. This suggests that vaccination may enhance the immune response. However, natural infection also established effective immune memory. During recovery, the severity of the infection only affected HEV-specific IgM. It did not affect HEV-specific IgG or memory T-cell expression profiles. This suggests that natural infection can also provide long-term protection. But, vaccination may provide a more consistent immune response. It may also have fewer side effects. This is an important consideration. It highlights the need for more research. Researchers need to understand the long-term effects of vaccination and natural infection. This knowledge can help improve prevention and treatment strategies for hepatitis E.