A vaccine is a biological preparation that provides active acquired immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as a threat, destroy it, and to further recognize and destroy any of the microorganisms associated with that agent that it may encounter in the future. Vaccines can be prophylactic, or therapeutic.
A cytotoxic T cell is a T lymphocyte that kills cancer cells, cells that are infected, or cells that are damaged in other ways.
Human orthopneumovirus, formerly Human respiratory syncytial virus (HRSV), is a syncytial virus that causes respiratory tract infections. It is a major cause of lower respiratory tract infections and hospital visits during infancy and childhood. A prophylactic medication, palivizumab, can be employed to prevent HRSV in preterm infants, infants with certain congenital heart defects (CHD) or bronchopulmonary dysplasia (BPD), and infants with congenital malformations of the airway. Treatment is limited to supportive care, including oxygen therapy and more advanced breathing support with CPAP or nasal high flow oxygen, as required.
Immunoglobulin G (IgG) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in blood circulation. IgG molecules are created and released by plasma B cells. Each IgG has two antigen binding sites.
Antigenic drift is a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites. This results in a new strain of virus particles which cannot be inhibited as effectively by the antibodies that were originally targeted against previous strains, making it easier for the virus to spread throughout a partially immune population. Antigenic drift occurs in both influenza A and influenza B viruses.
Polyomaviridae is a family of viruses whose natural hosts are primarily mammals and birds. As of the most recent (2016) taxonomy release by the International Committee on Taxonomy of Viruses, there were 77 recognized species in this family contained within four genera, as well as three species that could not be assigned to a genus. Of these, 13 species are known to infect humans. Most of these viruses, such as BK virus and JC virus, are very common and typically asymptomatic in most human populations studied. However, some polyomaviruses are associated with human disease, particularly in immunocompromised individuals; BK virus is associated with nephropathy in renal transplant and non-renal solid organ transplant patients, JC virus with progressive multifocal leukoencephalopathy, and Merkel cell virus with Merkel cell cancer.
Viral hemorrhagic fevers (VHFs) are a diverse group of animal and human illnesses in which fever and hemorrhage are caused by a viral infection. VHFs may be caused by five distinct families of RNA viruses: the families Arenaviridae, Filoviridae, Bunyaviridae, Flaviviridae, and Rhabdoviridae. All types of VHF are characterized by fever and bleeding disorders and all can progress to high fever, shock and death in many cases. Some of the VHF agents cause relatively mild illnesses, such as the Scandinavian nephropathia epidemica, while others, such as Ebola virus, can cause severe, life-threatening disease.
Antigenic variation refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters its surface proteins in order to avoid a host immune response. It is related to phase variation. Immune evasion is particularly important for organisms that target long-lived hosts, repeatedly infect a single host and are easily transmittable. Antigenic variation not only enables immune evasion by the pathogen, but also allows the microbes to cause re-infection, as their antigens are no longer recognized by the host's immune system. When an organism is exposed to a particular antigen an immune response is stimulated and antibodies are generated to target that specific antigen. The immune system will then "remember" that particular antigen, and defenses aimed at that antigen become part of the immune system’s acquired immune response. If the same pathogen tries to re-infect the same host the antibodies will act rapidly to target the pathogen for destruction. However, if the pathogen can alter its surface antigens, it can evade the host's acquired immune system. This will allow the pathogen to re-infect the host while the immune system generates new antibodies to target the newly identified antigen. Antigenic variation can occur by altering a variety of surface molecules including proteins and carbohydrates. There are many molecular mechanisms behind antigenic variation, including gene conversion, site-specific DNA inversions, hypermutation, as well as recombination of sequence cassettes. In all cases, antigenic variation and phase variation result in a heterogenic phenotype of a clonal population. Individual cells either express the phase-variable protein(s) or express one of multiple antigenic forms of the protein. This form of regulation has been identified mainly, but not exclusively, for a wide variety of surface structures in pathogens and is implicated as a virulence strategy.
HLA-A11 (A11) is a human leukocyte antigen serotype within HLA-A "A" serotype group. The serotype is determined by the antibody recognition of α11 subset of HLA-A α-chains. For A11, the alpha "A" chain are encoded by the HLA-A*11 allele group and the β-chain are encoded by B2M locus. This group currently is dominated by A*1101. A11 and A*11 are almost synonymous in meaning. A11 is more common in East Asia than elsewhere, it is part of a several long haplotypes that appear to have been frequent in the ancient peoples of Asia.
T-cell surface glycoprotein CD3 gamma chain is a protein that in humans is encoded by the CD3G gene.
Glycophorin A , also known as GYPA, is a protein which in humans is encoded by the GYPA gene. GYPA has also recently been designated CD235a.
T-cell surface glycoprotein CD3 delta chain is a protein that in humans is encoded by the CD3D gene.
Merkel cell polyomavirus was first described in January 2008 in Pittsburgh, Pennsylvania. It was the first example of a human viral pathogen discovered using unbiased metagenomic next-generation sequencing with a technique called digital transcriptome subtraction. MCV is one of seven currently known human oncoviruses. It is suspected to cause the majority of cases of Merkel cell carcinoma, a rare but aggressive form of skin cancer. Approximately 80% of Merkel cell carcinoma (MCC) tumors have been found to be infected with MCV. Three years later, a team of researchers at the Dana-Farber Cancer Institute developed an antibody that detected MCV expression in 97% of MCC tumors. MCV appears to be a common—if not universal—infection of older children and adults. It is found in respiratory secretions suggesting that it may be transmitted by a respiratory route. But it also can be found shedding from healthy skin, and in gastrointestinal tract tissues and elsewhere, and so its precise mode of transmission remains unknown. Most MCV viruses found in MCC tumors, however, have at least two mutations that render the virus nontransmissible: 1) The virus is integrated into the host genome in a monoclonal fashion and 2) The viral T antigen has truncation mutations that leave the T antigen unable to initiate DNA replication needed to propagate the virus.
The virus causing influenza is one of the best known pathogens found in various species. In particular, the virus is found in birds as well as mammals including horses, pigs, and humans. The phylogeny, or the evolutionary history of a particular species, is an important component when analyzing the evolution of influenza. Phylogenetic trees are graphical models of the relationships between various species. They can be used to trace the virus back to particular species and show how organisms that look so different may be so closely related.
The Heartland virus (HRTV) is a tick-borne phlebovirus of the Bhanja virus serocomplex discovered in 2009. The Lone Star Tick transmits the virus to people when feeding on blood. As of 2017, only five Midwestern United States have reported 20 human infections, namely Arkansas, Indiana, Missouri, Oklahoma, and Tennessee; symptoms resemble those of two other tick-borne infections ehrlichiosis and anaplasmosis. The reservoir host is unknown, but deer, raccoon, coyotes, and moose in 13 different states have antibody titers against the virus.
Sandfly fever Naples phlebovirus (SFNV) is an antigenic species of genus Phlebovirus within the family Phenuiviridae of the order Bunyavirales. It is an enveloped RNA virus with a tripartite genome e Uukuniemi (UUK) serogroup. The Sandfly group's natural reservoir are sandflies, while the natural reservoir for Uukuniemi is ticks. The SFNV serogroup consists of two main serocomplexes associated with disease in humans, the Naples and Sicilian serocomplexes. Sandfly fever induces myalgia, fever, and elevated liver enzymes in humans. It is difficult to diagnose outside endemic areas.
Amalgaviridae is a family of double-stranded RNA viruses that has one genus: Amalgavirus. Members of both the family and the genus are referred to as amalgaviruses. There are currently four recognized species of the family: Blueberry latent virus, Rhododendron virus A, Southern tomato virus, the type species of Amalgavirus, and Vicia cryptic virus M. The family and genus are called amalga, from amalgam, due to the viruses possessing characteristics of both partitiviruses and totiviruses, indicating a likely genetic relation to those two families. Members of this family infect plants and are transmitted vertically via seeds. Their genomes are monopartite, about 3.5 kilobases in length, and contain two partially overlapping open reading frames, encoding the RNA-dependent RNA polymerase (RdRp) and a putative capsid protein.
Influenza D virus is a species in the virus genus Influenzavirus D in the family Orthomyxoviridae, that causes influenza.
