INTRODUCTION
NICOLA DECARO AND CANIO BUONAVOGLIA
Department of Veterinary Public Health, Faculty of Veterinary Medicine of Bari, Valenzano (Bari), Italy
Parvoviruses (family Parvoviridae) are small (18—26 nm in diameter), non-enveloped viruses, with a linear, singlestrand DNA of 5,000—5,200 nucleotides.
The icosahedral capsid consists of 60 capsomers that are formed by two major structural proteins, VP1 and VP2, whereas a third capsid protein, VP3, arises from enzymatic cleavage of VP2. Parvoviruses replicate in the cell nuclei and, as a result of the limited genetic information contained in the small DNA molecule, for an optimal viral replication most of them need rapidly dividing cell populations in the synthesis (S) phase of the cell cycle. Consequently, parvoviruses are able to infect a variety of tissues with high replication rates, such as several tissues of fetuses and neonates and haematopoietic (bone marrow, lymphoid organs) and epithelial (intestine) tissues of adults. Their replication i n vivo is generally associated with the appearance of nuclear inclusion bodies, whereas the cytopathic effect induced in parvovirus- infected cell cultures is not always evident. All parvoviruses are highly stable in the environment, as they are extremely resistant to pH and temperature changes and to treatment with lipid solvents, trypsin and most disinfectants. Virions can be inactivated by formalin, sodium hypochlorite, beta-Propiolactone, hydroxylamine, oxidizing agents and ultraviolet irradiation. Several parvoviruses are able to agglutinate erythrocytes of different mammal and bird species, and some diagnostic tests for parvovirus infections rely on this haemagglutination activity.The family Parvoviridae comprises two subfamilies, Par- vovirinae and D ensovirinae, which infect vertebrates and arthropods, respectively. Currently, five genera are included in the subfamily Parvovirinae: namely Parvovirus, Erythro- virus, Dependovirus, Amdovirus and Bocavirus. Unlike other parvovirus genera, dependoviruses, also known as adeno- associated viruses, do not have an autonomous replication, but require co- infection with either an adenovirus or a herpesvirus for productive infection in cell cultures. Parvoviruses causing disease in wildlife are members of the genera Parvovirus (Canine parvovirus 2, Feline panleukopenia virus, Porcine parvovirus) and Amdovirus (Aleutian mink disease virus). Recently, novel parvoviruses closely related to human parvoviruses 4 and 5 have been detected in swine and cattle herds in Hong Kong. These viruses, tentatively assigned to a separate genus, Hokovirus, have also been found to circulate in wildlife, and antibodies against Porcine hokovirus have been detected in wild boar in Germany.
Infectious Diseases of Wild Mammals and Birds in Europe, First Edition. Edited by Dolores Gavier-Widen, J. Paul Duff, and Anna Meredith. © 2012 Blackwell Publishing Ltd. Published 2012 by Blackwell Publishing Ltd.
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