Adeno-associated viruses (AAVs) depend on a helper virus for efficient replication. To identify novel AAV isolates, we screened a diverse set of virus isolates for the presence of AAV DNA. AAVs found in 10 simian adenovirus isolates showed greater than 96% homology to AAV1 and AAV6 but had distinct biological properties. Two representatives of this group, AAV(VR-195) and AAV(VR-355), were studied in more detail. While the novel AAVs had high sequence homologies and required sialic acid for cell binding and transduction, differences were observed in lectin competition, resulting in distinct tropisms in human cancer cell lines.Adeno-associated virus (AAV) is a member of the Parvoviridae, a virus family characterized by a single-stranded linear DNA genome enclosed by a capsid with icosahedral symmetry. A hallmark of the AAV life cycle is its dependency on a helper virus for efficient productive replication. Adenovirus was originally identified as the AAV helper virus, but other viruses, such as herpesvirus and cytomegalovirus (7), can provide helper functions for AAV replication. Virus stocks have therefore served as a rich source for the discovery of AAV isolates; AAV1, AAV2, AAV3, AAV4, AAV6, and bovine AAV were all found as contaminants of adenovirus preparations (1-3, 8, 10-12, 15).In this article, we describe the analysis of virus stocks from the American Type Culture Collection (ATCC) for the presence of AAV DNA. Our goals were to identify ATCC virus isolates that contain AAV contaminations and, if novel, to characterize the isolates.Virus stocks supplied by the ATCC were analyzed for the presence of AAV DNA by a PCR-based assay, as described previously (5). AAV DNA was detected in 13 of 137 samples analyzed. AAV contaminations were frequently detected in adenovirus isolates (26%) but not in herpesvirus, retrovirus, coronavirus, orthomyxovirus, poxvirus, or reovirus stocks. The entire coding regions for the AAV Rep and Cap open reading frames were PCR amplified and subcloned, and several clones from each isolate were sequenced and analyzed. Adenovirusfree stocks of the novel recombinant AAVs were produced by standard cotransfection protocols (14).Ten of the AAVs detected in simian adenovirus stocks displayed at least 96% homology on the DNA level and 98% identity in the capsid amino acid sequence either to AAV1, to AAV6, or to each other. To determine whether these minor sequence changes could affect the biological activity of the isolates, 2 of the 10 isolates, AAV , and AAV(VR-355), isolated from ATCC respectively (GenBank accession numbers DQ180604 and DQ180605), were studied in greater detail. The VP1 capsid proteins of AAV and AAV(VR-355) differ by 7 and 6 amino acids, respectively, from that of AAV6. The locations of the divergent amino acids within the capsid were identified by superimposing the AAV(VR-195) and AAV(VR-355) VP1 sequences onto a pseudoatomic structure for AAV6 (Fig. 1). Divergent amino acids were found to cluster on the capsid surface around the threefold axis of symmetry, an area ...

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Possible factors for the higher B/M-ratio in referred patients are prompt referral to surgical biopsy, misinterpretation of mammograms, failure in the written report, lack of a second opinion and lack of feedback and communication between surgeon, pathologist and radiologist.