Showing papers on "Virus published in 1980"

Detection and isolation of type C retrovirus particles from fresh and cultured lymphocytes of a patient with cutaneous T-cell lymphoma

Abstract: Retrovirus particles with type C morphology were found in two T-cell lymphoblastoid cell lines, HUT 102 and CTCL-3, and in fresh peripheral blood lymphocytes obtained from a patient with a cutaneous T-cell lymphoma (mycosis fungoides). The cell lines continuously produce these viruses, which are collectively referred to as HTLV, strain CR(HTLVCR). Originally, the production of virus from HUT 102 cells required induction with 5-iodo-2′-deoxyuridine, but the cell line became a constitutive producer of virus at its 56th passage. Cell line CTCL-3 has been a constitutive producer of virus from its second passage in culture. Both mature and immature extracellular virus particles were seen in thin-section electron micrographs of fixed, pelleted cellular material; on occasion, typical type C budding virus particles were seen. No form of intracellular virus particle has been seen. Mature particles were 100-110 nm in diameter, consisted of an electron-dense core surrounded by an outer membrane separated by an electron-lucent region, banded at a density of 1.16 g/ml on a continuous 25-65% sucrose gradient, and contained 70S RNA and a DNA polymerase activity typical of viral reverse transcriptase (RT; RNA-dependent DNA nucleotidyltransferase). Under certain conditions of assay, HTLVCR RT showed cation preference for Mg2+ over Mn2+, distinct from the characteristics of cellular DNA polymerases purified from human lymphocytes and the RT from most type C viruses. Antibodies to cellular DNA polymerase γ and anti-bodies against RT purified from several animal retroviruses failed to detectably interact with HTLVCR RT under conditions that were positive for the respective homologous DNA polymerase, demonstrating a lack of close relationship of HTLVCR RT to cellular DNA polymerases γ or RT of these viruses. Six major proteins, with sizes of approximately 10,000, 13,000, 19,000, 24,000, 42,000, and 52,000 daltons, were apparent when doubly banded, disrupted HTLVCR particles were chromatographed on a NaDodSO4/polyacrylamide gel. The number of these particle-associated proteins is consistent with the expected proteins of a retrovirus, but the sizes of some are distinct from those of most known retroviruses of the primate subgroups.

Comparative Efficacy of Antiherpes Drugs against Different Strains of Herpes Simplex Virus

Abstract: A large variety of antiherpes compounds was compared for their inhibitory activity against laboratory strains and clinical isolates of herpes simplex virus (HSV) type 1 and type 2. From studies performed in primary rabbit kidney cell cultures, six, E-5-(2-bromovinyl)-2'-deoxyuridine, E-5-(2-iodovinyl)-2'-deoxyuridine, 5-vinyl-2'-deoxyuridine, 2'-fluoro-5-iodoaracytosine, acycloguanosine, and 5-iodo-2'-deoxycytidine, emerged as the most potent and selective antiherpes agents. For HSV type 1, the 50% inhibitory doses (ID50) were 0.008, 0.012, 0.018, 0.017, 0.04, and 0.06 micrograms/ml, respectively; those for HSV type 2 were 1, 2, 0.1, 0.05, 0.04, and 0.3 microgram/ml, respectively. These compounds did not inhibit host-cell metabolism or replication of vaccinia virus except at concentrations 100--10,000 times greater than the ID50 for any HSV. All were significantly less inhibitory for a thymidine kinase (TK)-deficient mutant of HSV type 1 than for normal strains, suggesting that phosphorylation by virus-induced TK was required to produce specific inhibition of HSV replication.

The virology and immunobiology of lymphocytic choriomeningitis virus infection.

Abstract: Publisher Summary This chapter presents in molecular terms the explanation for immunologic events accompanying lymphocytic choriomeningitis (LCM) infection, including the dual recognition of viral and histocompatibility antigens essential for T cell action and the modulation of viral expression result from the immune response. It discusses the important aspects of nonimmunologic regulation of viral infection particularly the role of defective interfering virus. Lymphocytic choriomeningitis virus (LCMV) and the infection it causes are important subjects of biomedical investigation. First, this virus sporadically causes human illness. The study of LCMV and the disease it causes in its natural murine host has provided the initial findings to open new fields in viral immunobiology, viral immunopathology, and cell–cell recognition. The apparent increased virulence of LCMV on passage through hamsters and the fact that LCMV infection can be transmitted from hamsters to humans suggest important concerns not only for investigators working with LCMV but for experimentalists who use hamsters or hamster tissues in their studies.

Virus of Pekin ducks with structural and biological relatedness to human hepatitis B virus.

Abstract: A virus found in the sera of Pekin ducks appears to be a new member of the human hepatitis B-like family of viruses. This virus had a diameter of 40 nm and an appearance in the electron microscope similar to that of human hepatitis B virus. The DNA genome of the virus was circular and partially single stranded, and an endogenous DNA polymerase associated with the virus was capable of converting the genome to a double-stranded circle with a size of ca. 3,000 base pairs. An analysis for viral DNA in the organs of infected birds indicated preferential localization in the liver, implicating this organ as the site of virus replication. In all of these aspects, the virus bears a striking resemblance to human hepatitis B virus and appears to be a new member of this family, which also includes ground squirrel hepatitis virus and woodchuck hepatitis virus.

A herpes simplex virus type 1 function continuously required for early and late virus RNA synthesis.

Abstract: Controlled transcription of animal virus DNAs provides potentially useful models for elucidating the mechanisms which regulate eukaryotic gene expression. The progressive transcription of the herpes simplex virus type 1 (HSV-1) genome has been described previously1–3. Infection of permissive cells with HSV-1 in the presence of the protein synthesis inhibitor cycloheximide resulted in transcription of a restricted set of virus RNAs, referred to as the immediate early RNAs, which map within certain regions of the virus genome only3–5. Removal of cycloheximide led to the transcription of additional virus DNA sequences, which were expressed during the normal replicative cycle both at early and late times post-infection (before and after the onset of virus DNA replication, respectively) and which map throughout the virus genome3. Previously, we have described a temperature-sensitive mutant of HSV-1 Glasgow strain 17, ts K, which accumulated only the immediate early RNAs at the non-permissive temperature (NPT)5. Transfer of ts K-infected cells from NPT to the permissive temperature (PT), even in the absence of de novo protein synthesis, resulted in transcription of the DNA sequences expressed early and late post-infection5. This indicated the persistence at NPT of a non-functional immediate early polypeptide which on transfer to PT regained its function, required for progression from the immediate early to early stage of transcription. Here we demonstrate, by analysing the RNAs made in ts K-infected cells after transfer from PT to the NPT, that this polypeptide's function is required continuously for synthesis of HSV-1 early and late RNAs, thus identifying a control function essential for the expression of early and late HSV genetic information in eukaryotic cells.

Nucleotide sequence of cDNA coding for Semliki Forest virus membrane glycoproteins

Abstract: The genes coding for the three membrane polypeptides of Semliki Forest virus have been sequenced and the primary structures of the proteins deduced. The amino acid sequence gives further insight into how the transmembrane structure of the three-chain virus membrane glycoprotein is generated in the infected cell.

Chronic Arthritis in Goats Caused by a Retrovirus

Abstract: A virus was isolated from an adult goat with chronic arthritis and shown to belong to the retrovirus group by electron microscopy and biochemical methods. Inoculation of the virus into cesarean-derived specific-pathogen-free goats' kids produced arthritic lesions similar to those in the spontaneous disease. Vrus was reisolated from the experimentally induced lesions.

A virus in Beechey ground squirrels that is related to hepatitis B virus of humans.

Abstract: A virus given the name ground squirrel hepatitis virus (or GSHV), with many of the unique characteristics of human hepatitis B virus (HBV), has been found in Beechey ground squirrels in northern California. Common features include virus morphology, viral DNA size and structure, a virion DNA polymerase that repairs a single-stranded region in the viral DNA, crossreacting viral antigens, and persistent infection with viral antigen continuously in the blood. Although similar, GSHV and HBV Are not identical. The ground squirrel virion has a slightly greater diameter, the viral surface antigens crossreact only partially and, thus, are not identical, and GSHV DNA has two restriction endonuclease EcoRI cleavage sites in contrast to the single site in HBV DNA. Thus, GSHV is a member of the virus group that includes HBV and the virus recently found in woodchucks in the eastern United States and named woodchuck hepatitis virus. It is not yet known how closely the ground squirrel and woodchuck viruses are related.

Significance of Extracellular Enveloped Virus in the in vitro and in vivo Dissemination of Vaccinia

Abstract: Summary The significance of extracellular enveloped vaccinia (EEV) for the in vitro and in vivo dissemination of vaccinia virus was investigated. The quantity of in vitro released extracellular virus correlated very closely with the ability of 13 vaccinia strains to cause long-range spread of infection (comet formation) in cell cultures infected at low m.o.i. but was not correlated with plaque size. The kinetics of virus spread after low m.o.i. was related to the amount of virus released from primary infected cells but not to their content of intracellular naked vaccinia (INV). Most extracellular vaccinia virus from IHD-J-infected RK-13 cells banded in CsCl density gradients as EEV (88%) while very little banded as INV (2%). Antisera to the envelope prevented comet formation while antisera to INV did not. CsCl centrifugation of blood-borne extracellular virus from rabbits infected intravenously with vaccinia virus after cyclophosphamide treatment revealed that 64% of the virus banded as EEV but only 11% as INV. High in vitro EEV-yielding vaccinia strains were able to spread from the respiratory tract to the brains of mice and cause death. Low in vitro EEV-yielding vaccinia strains were generally not able to disseminate in vivo or cause mouse mortality. The notable exception to this trend was strain WR, which, although releasing small amounts of virus in vitro, could nevertheless very effectively disseminate in vivo, causing a high rate of mouse mortality. Treatment with anti-envelope serum protected mice from a lethal vaccinia infection whereas antiserum to inactivated INV did not. These results indicate that the in vitro dissemination of vaccinia infection is mediated by EEV and implicate EEV as having a role in the in vivo dissemination.

The role of viral glycoproteins in adsorption, penetration, and pathogenicity of viruses.

Abstract: The F Glycoprotein 43 Protease activation mutants of a paramyxovirus 45 The activating protease 45 Proteolytic cleavage and viral virulence ..... 46 Structure of the F protein 47 Specific inhibition of virus-induced membrane fusion and virus penetration by oligopeptides 48 Importance of antibodies to F glycoprotein in prevention of spread of paramyxovirus infection 49

Rotavirus-Like, Calicivirus-Like, and 23-nm Virus-Like Particles Associated with Diarrhea in Young Pigs

Abstract: Virus particles morphologically similar to caliciviruses and rotaviruses were detected by electron microscopy (EM) in the intestinal contents of a 27-day-old diarrheic nursing pig. A third small spherical 23-nm virus-like particle was also observed. Calicivirus-like particles averaged 33 nm in diameter. Similar to rotaviruses, rotavirus-like particles were present as single-capsid 55-nm forms or double-capsid 70-nm particles. Most gnotobiotic pigs orally exposed to samples containing these three viruses developed diarrhea and villous atrophy of the small intestine, and all shed the three viruses in their intestinal contents. Attempts to propagate these viruses in cell culture were unsuccessful. The antigenic relationship of the rotavirus-like particles to known rotaviruses was explored by immune EM and immunofluorescent staining. By these techniques, the rotavirus-like particles did not cross-react with antisera to porcine, bovine, or human rotaviruses or to reovirus type 3. Antisera from gnotobiotic pigs exposed to all three viruses had enzyme-linked immunosorbent assay and virus neutralization titers of <4 against porcine rotavirus. Previous infection of gnotobiotic pigs with the mixture containing rotavirus-like particles failed to protect them against a subsequent challenge with porcine rotavirus. The antigenic relationship of the calicivirus-like particles to known caliciviruses was investigated by immune EM and virus neutralization. By these tests, the calicivirus-like particles did not react with antisera against feline calicivirus strain 255 or M-8. In a study conducted at Plum Island Animal Disease Center, antiserum against the three combined agents did not specifically neutralize any serotype of swine vesicular exanthema virus.

Lymphomagenicity of recombinant mink cell focus-inducing murine leukemia viruses.

Abstract: Recombinant mink cell focus-inducing (MCF) murine leukemic viruses, as well as ecotropic and xenotropic viruses, were tested for ability to accelerate or cause development of lymphoma in AKR and other strains of mice. Of the three classes of virus isolated from AKR, only the MCF viruses were able to accelerate development of AKR lymphoma. This fully supports the idea that the MCF viruses are the proximal cause of spontaneous AKR lymphoma. MCF lymphomagenicity was strain specific, however, in that AKR MCF viruses did not induce lymphomas in many murine strains; they were moderately lymphomagenic in C3H/Bi mice and in National Institutes of Health Swiss partially congenic for Akv-1 or Akv-2. In contrast, MCF viruses from nonthymic hematopoietic neoplasms of C3H/Fg, BALB/c, or mice partially congenic for ecotropic virus loci (Akv-1, Akv-2, Fgv-1, C58v-1, and C58v-2) were not able to accelerate or cause lymphomia in AKR or any other mouse strain tested, including some of the strains of origin. MCF lymphomagenicity correlated with thymic origin in the virus and with ability to replicate in the thymus.

Integration of the adeno-associated virus genome into cellular DNA in latently infected human Detroit 6 cells.

Abstract: A clone of human cells (Detroit 6) latently infected by adeno-associated virus (AAV) has been characterized with regard to the status of the viral DNA. In both early (9 to 10) and late (118) passages of the clone, AAV-DNA was recombined with host DNA, at least in some cases as a head-to-tail tandem repeat, via the terminal sequences of the viral genome. However, it was not possible to distinguish between integration into chromosomal DNA and very large plasmids (< 20 x 10(6) molecular weight) which contain both viral and cellular DNA sequences. Although evidence for some modifications of the viral sequence was obtained, most of the integrated sequences appeared to be intact. In some cases sequences of undetermined origin separated adjacent copies of the viral genome. Free copies of the AAV genome were detectable in late passage cells, but not in early passage cells. The orientation of nucleotide sequences present in the free AAV DNA from late passage cells was indistinguishable from that of virion DNA. With the notable exception, the organization of the integrated AAV sequences as determined by restriction enzyme digestion remained constant with continued passage. Digestion with SmaI, which cleaves within the palindromic region of the terminal repetition in AAV DNA, produced reproducibly different patterns when early and late passage DNAs were compared. Several models for rescue of free copies of the genome from the integrated DNA are possible, all of which involve the terminal repetition.

Duck influenza lacking evidence of disease signs and immune response.

Abstract: Influenza viruses A/duck/Hokkaido/5/77 (Hav7N2), A/budgerigar/Hokkaido/1/77 (Hav4Nav1), A/Kumamoto/22/76 (H3N2), A/Aichi/2/68 (H3N2), and A/New Jersey/8/76 (Hsw1N1) were experimentally inoculated into Pekin ducks. Of these, the influenza viruses of duck and budgerigar origin replicated in the intestinal tract of the ducks. The infected ducks shed the virus in the feces to high titers, but did not show clinical signs of disease and scarcely produced detectable serum antibodies. Using immunofluorescent staining, we demonstrated that the target cells of the duck virus in ducks were the simple columnar epithelial cells which form crypts in the large intestines, especially in the colon. After primary infection, the birds resisted reinfection with the duck virus at least for 28 days, but from 46 days onward they were susceptible to reinfection. These infections were quickly restricted by a brisk secondary immune response, reflected in the rapid appearance of high titers of antibody after reinoculation. In contrat to the avian influenza viruses, the remaining three influenza viruses of human origin did not replicate in the intestinal tract but did cause a serum antibody response.

Assay of transforming activity of tumor virus DNA.

Abstract: Publisher Summary This chapter describes the assay of transforming activity of tumor virus DNA. Several techniques have been developed for assaying biological activity of DNA extracted from mammalian viruses. These methods measure the infectivity of viral nucleic acid preparations in cultured cells. This technique was developed as an assay for infectivity of adenovirus DNA, which also appeared suitable for demonstrating transformation with several viral DNAs. The diethylaminoethanol (DEAE)-dextran and the calcium technique have been used in virus research. A possible reason for the failure to obtain transformation with the DEAE-dextran technique may be the relative toxicity of this compound for many cultured cells. The chapter describes the procedures for assaying transformation of cultured cells by viral DNA or DNA fragments, in particular of adenovirus and SV40 DNA. The only method suitable for the demonstration of transforming activity with these viral DNAs is the calcium technique, therefore, the chapter discusses this method and the modifications developed to enhance its effectiveness.

Coding potential and regulatory signals of the polyoma virus genome.

Abstract: The complete DNA sequence of the A2 strain of polyoma virus has been determined. It consists of 5,292 base pairs. The sequence is analysed in terms of its coding potential and sites of possible functional significance or structural interest. The polyoma virus genome is compared with those of related tumour viruses, simian virus 40 and BK virus.

Direct transfer of cloned genes from bacteria to mammalian cells

Abstract: Induction of a virus infection by cloned simian virus 40 DNA was chosen as a test system to detect transfer of genes from bacteria to cultured mammalian cells. Escherichia coli cells containing a recombinant plasmid with three tandem inserts of simian virus 40 DNA were able to infect CV-1 monkey cells under various conditions. The gene transfer was resistant to DNase I and therefore seems not to occur via free DNA but most likely via uptake of whole bacteria, followed by release of plasmid DNA and generation of infectious circular simian virus 40 DNA in a recombination-excision process. Spontaneous transfer was found to be infrequent, 4 x 10(9) bacteria yielding one infection per 10(7) monkey cells. The frequency was greatly increased by adding bacteria as a calcium phosphate coprecipitate or by fusion of lysozyme-treated bacteria (protoplasts) with monkey cells in the presence of polyethylene glycol. With the latter technique, 10(4) protoplasts gave rise to one infection per 15 monkey cells. Experiments with other cell lines of human, monkey, and mouse origin, and also with bacteria harboring another recombinant plasmid, indicate that DNA transfer from bacteria to mammalian cells is a general phenomenon.

Integration of hepatitis B virus sequences and their expression in a human hepatoma cell

Abstract: Hepatitis derived from hepatitis B virus (HBV) infection is endemic throughout the world, but it is particularly prevalent in Asia and Africa. In these areas, demographic studies show a strong coincidence between HBV infection (assayed by HBV antigenic markers) and the incidence of primary liver cancer. On these grounds, a causal link between HBV infection and primary hepatocellular cancer has been proposed. Recently, a human hepatoma cell line (PLC/PRF/5; Alexander cells) has been shown to produce hepatitis B surface antigen (HBsAg). We show here that the Alexander cell line contains at least six (four complete and two partial) hepatitis B viral genomes integrated into high molecular weight host DNA. An analysis using specific probes to fragments of the HBV genome suggests that integration of the virus in most cases occurs at the nicked cohesive end region of the virus. Expression of viral sequences using Northern blots demonstrates the presence of RNA transcripts specific for the surface antigen sequences of HBV DNA and the absence of detectable transcripts corresponding to the hepatitis B core antigen.

Importance of antibodies to the fusion glycoprotein of paramyxoviruses in the prevention of spread of infection.

Abstract: The effects of monospecific antibodies to the viral glycoprotein with hemagglutinating and neuraminidase activity (HN) and the viral glycoprotein with membrane-fusing activity (F) of the paramyxovirus simian virus 5 (SV5) on the spread of infection in two cell types have been investigated. In CV-1 cells, infection can spread by either released progeny virus adsorbing to and infecting other cells, or by fusion of an infected cell with an adjacent cell as a result of the cell-fusing activity of the F glycoprotein. In these cells, antibodies specific for the HN glycoprotein prevented the dissemination of infection by released infectious virus, but spread by cell fusion was not inhibited. Antibodies to the F glycoprotein completely prevented the spread of infection in these cells. In Madin-Darby bovine kidney cells, which are relatively resistant to SV5-induced fusion, antibodies to either the HN or F glycoproteins were capable of preventing the dissemination of infection. These results indicate that effective immunological prevention of the spread of paramyxovirus infection requires the presence of antibodies that inactivate the F glycoprotein. This requirement for anti-F antibodies has obvious implications for the design of effective paramyxovirus vaccines and provides an explanation for previous failures of formalin-inactivated paramyxovirus vaccines as well as additional insight into the possible immunopathological mechanisms involved in the atypical and severe infections that have occurred in individuals who received inactivated paramyxovirus vaccines and were subsequently infected by the virus.

Human rotavirus type 2: cultivation in vitro

Abstract: A strain of type 2 human rotavirus (Wa) was grown to relatively high titer through 14 passages in primary cultures of African green monkey kidney (AGMK) cells. This passage series was initiated with virus that had been passaged 11 times serially in newborn gnotobiotic piglets. In contrast, virus present in the stool of patient Wa as well as virus from the first, second, or third passage in piglets could not be propagated successfully in African green monkey kidney cells. Prior to each passage in cell culture, the virus was treated with trypsin and the inoculated cultures were centrifuged at low speed. Cultivation of a type 2 human rotavirus should aid attempts to characterize this virus and to develop a means of immunoprophylaxis for a serious diarrheal disease of human infants.

Pathogenicity in mice of strains of herpes simplex virus which are resistant to acyclovir in vitro and in vivo.

Abstract: Mice infected with three different isolates of herpes simplex virus (HSV) and treated with acyclovir (acycloguanosine; ACV) showed low levels of virus replication during the acute phase of infection However, virus isolated from such treated mice did not show increased resistance to ACV In contrast, resistant virus was readily isolated in vitro by passaging HSV in the presence of the drug The degree of resistance was determined, in part, by the nature of the cells used to test the virus The majority of ACV-resistant strains induced low or undetectable levels of HSV-specified thymidine kinase (TK), the enzyme responsible for phosphorylating ACV in infected cells The TK-resistant strains were attenuated when injected into mice as indicated by reductions in virus replication, inflammation, and establishment of latent infections in sensory ganglia The reduced virulence of the TK- strains was most marked after intracerebral inoculation, where the lethal dose was increased more than 100-fold compared with the parental isolates However, one mutant is described which induced high levels of TK but was highly resistant to ACV and retained virulence for mice

Expression of leukemogenic recombinant viruses associated with a recessive gene in HRS/J mice.

Abstract: HRS/J inbred mice carry a mutant autosomal recessive gene (hr), which in homozygotes coincides with susceptibility to spontaneous thymic leukemia. Unlike their heterozygote (hr/+) littermates, hr/hr homozygotes express high levels of xenotropic virus during the preleukemic period, and viruses with a broadened host range (termed polytropic viruses) can be isolated from their preleukemic and leukemic tissues. Because hr/hr and hr/+ mice are otherwise genetically identical, the virological differences between them support the role of polytropic viruses in the generation of thymic leukemia. In the present report we show that the HRS/J polytropic viruses are env gene recombinants with unique oligonucleotide and peptide maps. These polytropic viruses appear to arise by recombination between ecotropic virus and an unidentified genome related, but not identical to, the endogenous xenotropic viruses. Moreover, polytropic viruses not only accelerate leukemogenesis in HRS/J mice, but also induce thymic leukemia in the low leukemia strain CBA/J. By contrast, cloned ecotropic and xenotropic viruses have no leukemogenic action.

Monoclonal antibody against a 250,000-dalton glycoprotein of Epstein-Barr virus identifies a membrane antigen and a neutralizing antigen

Abstract: An antibody-secreting hybrid cell line was produced by fusion of mouse myeloma cells with splenocytes from mice immunized with virions of the B95-8 strain of Epstein-Barr Virus (EBV). The monoclonal IgG antibody was shown to have anti-EBV activity by the following criteria: (i) It reacted with the membranes and the cytoplasm of seven different EBV-producing lines, but with no nonproducing line. (ii) The individual cells identified by the murine antibody were shown to be the same cells identified by a human serum having anti-EBV activity. (iii) The antibody significantly reduced the infectivity of two independent strains of EBV (namely, P3HR1K and B95-8). The antigen being recognized was characterized by immunoprecipitations of radiolabeled EBV-producer cell lysates. A single glycoprotein with an estimated molecular weight of 250,000 was identified. It is concluded that neutralization of EBV can be achieved by an IgG-class monoclonal antibody directed against a single antigenic site on a 250,000-dalton glycoprotein, which is a constituent of the EBV virion.

Human Polyomavirus Infections with JC Virus and BK Virus in Renal Transplant Patients

Abstract: Infection with the human polyomaviruses JC virus and BK virus was studied in 61 immunosuppressed renal transplant patients. Urine cytologic studies, indirect immunofluorescence microscopy, electron microscopy, and serologic studies were used to assess viral activity. Patients records were abstracted for events associated with polyomavirus infections. Polyomavirus excretion in urine was detected in 12 of 61 patients (20%). Eleven excreted JC virus and nine, BK virus. Fourfold hemagglutination-inhibition antibody titer rises occurred in 25 of 61 patients (41%). The serologic data suggested that most JC virus infections were primary, whereas most BK virus infections resulted from virus reactivation. During this 2-year study, 32 of 61 patients (52%) had evidence of active viral replication. Urinary tract excretion was associated with drug-requiring diabetes mellitus (P = 0.001), arterial occlusive disease (P = 0.03), and ureteral stricture with loss of renal function (P = 0.02). Antibody increases to BK virus were associated with a rising seurum creatinine (P = 0.02) and need for transplant biopsy (P = 0.02). Polyomavirus replication was therefore associated with an increased frequency of transplant related complications.