RESUMO
Porcine parvovirus is an autonomous parvovirus which normally infects pigs and multiplies in porcine cells in vitro. In this report, we describe the properties of a variant designated P2, which has extended its host range to include canine cells. The variant was able to produce cytopathic effects (CPE) in canine cells, unlike the prototype NADL-2 strain. The variant also produced higher viral antigen and infectivity titers in canine cells than the NADL-2 strain, whereas both strains produced CPE and similar titers in porcine cells. Generation of recombinant plasmids between the P2 variant DNA and an infectious clone of NADL-2, and analysis of the properties of the virus stocks produced from these recombinant plasmids, indicated that two changes were necessary for this extension in the host range. One change was located in the nonstructural protein coding region and the other in the capsid coding region.
Assuntos
Capsídeo/fisiologia , Parvoviridae/crescimento & desenvolvimento , Proteínas do Core Viral/fisiologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Capsídeo/química , Efeito Citopatogênico Viral , Análise Mutacional de DNA , DNA Recombinante , Cães/microbiologia , Genes Virais , Dados de Sequência Molecular , Parvoviridae/genética , Conformação Proteica , Especificidade da Espécie , Suínos/microbiologia , Proteínas do Core Viral/química , Proteínas não Estruturais Virais , Proteínas Estruturais Virais/genéticaRESUMO
The complete nucleotide sequence of an infectious clone of porcine parvovirus, strain NADL-2, was determined. The nucleotide sequence organization of the viral genome was found to be similar to that of the other autonomous parvoviruses, such as canine parvovirus and minute virus of mice.
Assuntos
Parvoviridae/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Células Cultivadas , Clonagem Molecular , DNA Viral/química , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Parvoviridae/ultraestrutura , Regiões Promotoras Genéticas , SuínosRESUMO
The genome of the porcine parvovirus, strain NADL-2, has been cloned and the sequence of map units 28 to 100, which is 3670 bp in length and contains the capsid coding regions and the right-hand terminal palindrome, has been determined. The sequence shows extensive homology with other parvoviruses such as MVM, H-1, CPV, and FPV in the capsid coding region. Given the information available from these sequences, the regulatory and capsid coding regions for PPV have been proposed and the amino acid sequences of capsid proteins compared. The right end, which has a 188-nucleotide-long imperfect palindromic sequence, has an organization similar to that of other parvoviruses and the homologies in this region with other parvoviruses correspond to the homologies observed in the rest of the respective genomes.
Assuntos
Capsídeo/genética , Parvoviridae/genética , RNA Viral/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , Códon/genética , Dados de Sequência Molecular , Conformação de Ácido Nucleico , RNA Mensageiro/genética , Sequências Repetitivas de Ácido Nucleico , Homologia de Sequência do Ácido NucleicoRESUMO
Trypanosoma brucei brucei is an important pathogen of domestic cattle in sub-Saharan Africa and is closely related to the human sleeping sickness parasites, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. However, T. b. brucei is non-infectious to humans. The restriction of the host range of T. b. brucei results from the sensitivity of the parasite to lysis by toxic human high density lipoproteins (HDL) (Rifkin, M. R. (1978) Proc. Natl. Acad. Sci. U.S.A. 75, 3450-3454). We show in this report that trypanosome lytic activity is not a universal feature of all human HDL particles but rather that it is associated with a minor subclass of HDL. We have purified the lytic activity about 8,000-fold and have identified and characterized the subspecies of HDL responsible for trypanosome lysis. This class of HDL has a relative molecular weight of 490,000, a buoyant density of 1.21-1.24 g/ml, and a particle diameter of 150-210 A. It contains apolipoproteins AI, AII, CI, CII, and CIII, and monoclonal antibodies against apo-AI and apo-AII inhibit trypanocidal activity. In addition to these common apolipoproteins, the particles also contain at least three unique proteins, as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions. Treatment of the particles with dithiothreitol resulted in the disappearance of two of the proteins and abolished trypanocidal activity. Two-dimensional gel electrophoresis showed that these proteins were a disulfide-linked trimer of 45,000, 36,000, and 13,500-Da polypeptides and dimers of the 36,000- and 13,500-Da polypeptides or of 65,000- and 8,500-Da polypeptides. Studies on the lysis of T. b. brucei by the purified particle suggest that the lytic pathway may involve the uptake of the trypanocidal subspecies of HDL by endocytosis.
