Parvovirus B19 Achievements and Challenges

Parvovirus B19 is a widespread human pathogenic virus, member of the Erythrovirus genus in the Parvoviridae family. Infection can be associated with an ample range of pathologies and clinical manifestations, whose characteristics and outcomes depend on the interplay between the pathogenetic potential of the virus, its adaptation to different cellular environments, and the physiological and immune status of the infected individuals. The scope of this review is the advances in knowledge on the biological characteristics of the virus and of virus-host relationships; in particular, the interactions of the virus with different cellular environments in terms of tropism and ability to achieve a productive replicative cycle, or, on the contrary, to establish persistence; the consequences of infection in terms of interference with the cell physiology; the process of recognition of the virus by the innate or adaptive immune system, hence the role of the immune system in controlling the infection or in the development of clinical manifestations. Linked to these issues is the continuous effort to develop better diagnostic algorithms and methods and the need for development of prophylactic and therapeutic options for B19V infections. 1. Introduction Human parvovirus B19 (B19V) is a human pathogenic virus, member of the Erythrovirus genus in the Parvoviridae family. Structural features of parvovirus B19 are common to viruses in the family, and include a genome constituted by a molecule of linear single-stranded DNA of either positive or negative polarity, about 5600 bases in length, encapsidated in isometric virions, and approximately 25？nm in diameter. Infection is widespread and can be associated with an ample range of pathologies and clinical manifestations, whose characteristics and outcomes depend on the interplay between the pathogenetic potential of the virus, its adaptation to different cellular environments, and the physiological and immune status of the infected individuals. The virus shows a marked tropism for erythroid progenitor cells in the bone marrow, exerting a cytotoxic effect and causing a block in erythropoiesis that can be manifested as a transient or persistent erythroid aplasia. However, the virus has the capability to infect several different cellular types, as inferred from the detection of viral nucleic acids, and sometimes viral proteins, in diverse tissues, and the pathogenetic potential of the virus is ample. The most common clinical manifestations of infection are erythema infectiosum mainly in children or postinfection arthropathies