Five years later, a laboratory in Japan also identified the same virus and called it the “Nakatani” virus. This implies that the human parvovirus is already widespread and has reached practically all corners of the world. In 1985, the International Committee on Taxonomy of Viruses officially assigned the name “B19” to the human parvovirus.
The human parvovirus belongs to one of the largest group of viruses. There are parvoviruses for almost every known mammal. There are feline parvoviruses, canine parvoviruses, mouse parvoviruses, and pig parvoviruses. These viruses are considerably smaller than the average virus, thus they were given the name “parvo”, a derivation from the Latin word “parvum”, which means “small”. Of course, smaller viruses, such as the circoviruses and TT viruses, were discovered since then.
The human parvovirus officially belongs to the family “Parvoviridae”, a group of pathogens that attack Homo sapiens and other mammals. Some parvoviruses need the help of other viruses to strike an organism, while others can wreak destruction by themselves. The human parvoviruses belong to the latter sub-group, called the Erythrovirus genus. So far, only the B19 belongs to this genus, but taxonomists suggest that the monkey parvoviruses should also be classified in the Erythrovirus genus.
The human parvovirus has a simple structure. There is one tiny, linear, and single-stand DNA molecule protected by a capsid, which is made up of two proteins. The small size of the DNA molecule does not make the human parvovirus weak or defenseless. In fact, the opposite happens.
The simplicity of the DNA made the human parvovirus invulnerable to many substances. It cannot be easily destroyed by heat, cold, water, or sunlight. So far, the chemicals and method that can destroy the human parvovirus are also lethal to the human. The chemicals are formalin, and beta-propiolactone (a substance that can sterilize the human arterial grafts). The method that can render the virus useless is the irradiation of dangerous gamma rays.
Like many other viruses, the human parvovirus or B19 infects its hosts this way:
- The parvovirus attaches itself to a host cell
- It sends the contents of the capsid to the nucleus of the host cell where it uses the host cell’s proteins to create a new set of DNA traits.
- The DNA replicates and produces more capsids containing the “improved virions”
- The host cell is destroyed and the lethal and mature virions are sent to attack other organs of the body.
The most dangerous incident that recently occurred was the discovery of a variant of B19 found in a French child who has aplastic anemia. This variant is given the temporary name V9. The existence of the V9 is not yet well-studied, but it implies that the human parvovirus may be evolving.