Bunka DH, Lane SW, Lane CL, Dykeman EC, Ford RJ, Barker AM, Twarock R, Phillips SE, Stockley PG. 2011. and LuIII, are promising candidates for antitumor delivery vectors, particularly for cytoreductive and immunogene therapy approaches (reviewed in recommendations 4 and 5). The inherent Aripiprazole (Abilify) oncotropism of these autonomous parvoviruses is based on their dependence on cellular proliferation factors expressed during the S phase and the differentiated state of the host cell (6, 7). The Rabbit Polyclonal to APC1 rodent parvoviruses display oncopreferential cytotoxic activity and also possess an oncosuppressive potential, inhibiting the formation of spontaneous and chemical or virus-induced tumors and (8C13). These viruses can also persistently infect their natural hosts, do not integrate their genome into cellular chromosomes, and Aripiprazole (Abilify) are not associated with human disease (reviewed in reference 4). Recombinant rodent parvovirus vectors targeted for tumor therapy utilize a double-edged strategy that takes advantage of their inherent oncotropism and selective cytotoxicity plus their ability to deliver therapeutic genes that code for toxins, such as thymidine kinase, or host immune response enhancers, such as cytokines/chemokines (14C19). The first clinical study of H-1PV in 1965 injected wild-type (wt) computer virus into two osteosarcoma patients (20). This treatment did not completely ablate tumor development, possibly due to the generation of neutralizing Aripiprazole (Abilify) antibodies. In other studies, H-1PV was assessed for the killing of human neuroblastoma and hepatoma cells and exhibited tumor-selective lytic effects and low toxicity for nontransformed cells (21, 22). Local, intranasal, or systemic treatment of advanced rat and human gliomas in rat models with H-1PV was also reported to induce regression (23, 24). These promising results set the stage for the first phase I/IIa clinical trial using replication-competent H-1PV in patients with progressive primary or recurrent glioblastoma multiforme (25). The parvoviruses encapsulate a linear ssDNA genome of 5 kb, with small terminal palindromes, into a T=1 icosahedral capsid with an overall diameter of 260 ?. The H-1PV genome encodes two nonstructural proteins (NS; NS1 and NS2) and two capsid viral proteins (VPs; VP1 and VP2), driven by promoters P4 and P38, respectively. NS1 (76 kDa) is usually a phosphoprotein with helicase, ATPase, DNA-nicking, and sequence-specific DNA binding activities essential for replication, and it is also the major mediator of cytotoxicity (26). NS2 (21 kDa) is also required for computer virus replication and cytotoxicity (26). The capsid VPs are overlapping in amino acid sequence, with VP1 (81 kDa) and VP2 (65 kDa) produced by alternative splicing from the same mRNA, and are expressed at a ratio of 1 1:5 (27). VP1 and VP2 have a common C-terminal sequence (593 amino acids [aa]), with VP1 made up of a unique N-terminal region of 142 amino acids (VP1u). In wt virions (DNA made up of) but not in vacant capsids, VP3 is usually generated by posttranslational cleavage of 18 or 21 amino acids from the N terminus of VP2 (but not of VP1). VP1 is present at 10 copies per virion or capsid (of 60 VPs) with 50 copies of VP2 Aripiprazole (Abilify) in vacant capsids or a mixture of VP2 and VP3 in virions, with VP3 being the major component. The structures for several members of the mammalian have been decided using X-ray crystallography and/or cryoelectron microscopy and image reconstruction (cryoreconstruction), including those of MVM, canine parvovirus (CPV), feline panleukopenia computer virus (FPV), and porcine parvovirus (PPV) (28C36). In most of these structures, only 520 to 550 residues (depending on the computer virus) of VP2 (or VP3 in virions) in the overlapping polypeptide region is observed. The only exception is the cryoreconstructed Aripiprazole (Abilify) structure of B19V, in which the N-terminal amino acids were also ordered (37). Despite differences in amino acid sequence between family members, the VP structural topology is usually highly conserved among the parvoviruses (38). Variable capsid surface loops govern many biological functions, including receptor binding, tissue tropism, pathogenicity, and antigenicity, and also form the structural basis of the phenotypic differences among members and between strains of the same computer virus (39). Here, we report the structure determination of H-1PV virions and vacant capsids using X-ray crystallography to 2.7- and 3.2-? resolution, respectively. These structures differ only in the side chain conformations for some of the residues that surround nucleotides ordered in a conserved parvovirus DNA binding pocket in the virion structure. This indicates a potential evolutionarily conserved role in capsid DNA packaging and stability. The VP structure conserves the -barrel and A helix topology previously reported for other parvoviruses, including CPV,.