B-Cell Development Stages. stem cell –> early pro-B cell –> late pro-B cell –> large pre-B cell –> [1st checkpoint – selects for functional heavy chains] –> small pre-B cell –> [2nd checkpoint – select for functional light chains] –> Immature B cell (has surface IgM, no surface IgD). Somatic recombination is the process in which different individual gene segments of the H (heavy) chain combine with rearranged gene segments of the L (light) chain. The enzymes responsible for somatic recombination are the recombinase enzymes (RAG-1 and RAG-2) that recognize specific sequences (RSS) or recombination signal sequences. RAG-1 and RAG-2 are only expressed in B or T lymphocytes. These specific sequences recognized by the RAG-1 or RAG-2 enzymes are either a 1) heptamer or 2) nonamer. The heptamer literally contains 7 nucleotides, and the nonamer literally contains 9 nucleotides. There are typically 12 or 23 nucleotides in between the heptamer and nonamer to separate them.
Retroviruses are a class of viruses that not only infect host cells but also integrate their genetic material into the host genome, establishing a permanent infection that cannot be cured. The most common retrovirus is the human immunodeficiency virus or HIV, which targets and destroys helper T-cells.
The question of how a vaccination would work to combat the current COVID-19 pandemic is a major concern right now. Everybody has their own perspective on the situation, and in some people’s minds, vaccines do not fit into the equation. Therefore, it’s extremely important to understand what a vaccine’s purpose is, how it is supposed to achieve that purpose, how a vaccine is developed, and its benefits versus side effects before coming to a final conclusion on the subject as it relates to the pandemic. To understand a vaccination’s purpose it is necessary to first understand how a pathogen works. A pathogen is essentially any foreign material (foreign in the sense that it is not a part of the human body), that can cause disease or a malfunction of the body. They spread from surface to surface and person to person.
Innate vs Adaptive Immunity: What are the differences between innate and adaptive immunity? The human body has two protective immunological systems against pathogens: the innate immunity and the adaptive immunity. In this quick and easy lesson, we will explain the differences between the innate and adaptive immunity. The innate immunity and adaptive immunity differ based on the type of components that are used to protect the human body. For example, the innate immunity consists of neutrophils, dendritic cells, natural killer cells, macrophages, complements, physical barriers. On the other hand, the adaptive immunity contains components such as T cells, B cells, and antibodies to protect us from viruses, bacteria, and other pathogens.