In-depth investigation of archival and prospectively collected samples reveals no evidence for XMRV infection in prostate cancer

XMRV, or xenotropic murine leukemia virus (MLV)-related virus, is a novel gammaretrovirus originally identified in studies that analyzed tissue from prostate cancer patients in 2006 and blood from patients with chronic fatigue syndrome (CFS) in 2009. However, a large number of subsequent studies failed to confirm a link between XMRV infection and CFS or prostate cancer. On the contrary, recent evidence indicates that XMRV is a contaminant originating from the recombination of two mouse endogenous retroviruses during passaging of a prostate tumor xenograft (CWR22) in mice, generating laboratory-derived cell lines that are XMRV-infected. To confirm or refute an association between XMRV and prostate cancer, we analyzed prostate cancer tissues and plasma from a prospectively collected cohort of 39 patients as well as archival RNA and prostate tissue from the original 2006 study. Despite comprehensive microarray, PCR, FISH, and serological testing, XMRV was not detected in any of the newly collected samples or in archival tissue, although archival RNA remained XMRV-positive. Notably, archival VP62 prostate tissue, from which the prototype XMRV strain was derived, tested negative for XMRV on re-analysis. Analysis of viral genomic and human mitochondrial sequences revealed that all previously characterized XMRV strains are identical and that the archival RNA had been contaminated by an XMRV-infected laboratory cell line. These findings reveal no association between XMRV and prostate cancer, and underscore the conclusion that XMRV is not a naturally acquired human infection.

Absence of XMRV and closely related viruses in primary prostate cancer tissues used to derive the XMRV-infected cell line 22Rv1

The 22Rv1 cell line is widely used for prostate cancer research and other studies throughout the world. These cells were established from a human prostate tumor, CWR22, that was serially passaged in nude mice and selected for androgen independence. The 22Rv1 cells are known to produce high titers of xenotropic murine leukemia virus-related virus (XMRV). Recent studies suggested that XMRV was inadvertently created in the 1990's when two murine leukemia virus (MLV) genomes (pre-XMRV1 and pre-XMRV-2) recombined during passaging of the CWR22 tumor in mice. The conclusion that XMRV originated from mice and not the patient was based partly on the failure to detect XMRV in early CWR22 xenografts. While that deduction is certainly justified, we examined the possibility that a closely related virus could have been present in primary tumor tissue. Here we report that we have located the original prostate tumor tissue excised from patient CWR22 and have assayed the corresponding DNA by PCR and the tissue sections by fluorescence in situ hybridization for the presence of XMRV or a similar virus. The primary tumor tissues lacked mouse DNA as determined by PCR for intracisternal A type particle DNA, thus avoiding one of the limitations of studying xenografts. We show that neither XMRV nor a closely related virus was present in primary prostate tissue of patient CWR22. Our findings confirm and reinforce the conclusion that XMRV is a recombinant laboratory-generated mouse virus that is highly adapted for human prostate cancer cells.

In vivo hypermutation of xenotropic murine leukemia virus-related virus DNA in peripheral blood mononuclear cells of rhesus macaque by APOBEC3 proteins

The gammaretrovirus, xenotropic murine leukemia virus-related virus (XMRV), replicates to high titers in some human cell lines and is able to infect non-human primates. To determine whether APOBEC3 (A3) proteins restrict XMRV infections in a non-human primate model, we sequenced proviral DNA from peripheral blood mononuclear cells of XMRV-infected rhesus macaques. Hypermutation characteristic of A3DE, A3F and A3G activities was observed in the XMRV proviral sequences in vivo. Furthermore, expression of rhesus A3DE, A3F, or A3G in human cells inhibited XMRV infection and caused hypermutation of XMRV DNA. These studies show that some rhesus A3 isoforms are highly effective against XMRV in the blood of a non-human primate model of infection and in cultured human cells.

Characterization of antibodies elicited by XMRV infection and development of immunoassays useful for epidemiologic studies

Background

Xenotropic Murine Leukemia Virus-related Virus (XMRV) is a human gammaretrovirus recently identified in prostate cancer tissue and in lymphocytes of patients with chronic fatigue syndrome. To establish the etiologic role of XMRV infection in human disease requires large scale epidemiologic studies. Development of assays to detect XMRV-specific antibodies would greatly facilitate such studies. However, the nature and kinetics of the antibody response to XMRV infection have yet to be determined.

Results

Three rhesus macaques were infected with XMRV to determine the dynamics of the antibody responses elicited by infection with XMRV. All macaques developed antibodies to XMRV during the second week of infection, and the predominant responses were to the envelope protein gp70, transmembrane protein p15E, and capsid protein p30. In general, antibody responses to gp70 and p15E appeared early with higher titers than to p30, especially in the early period of seroconversion. Antibodies to gp70, p15E and p30 persisted to 158 days and were substantially boosted by re-infection, thus, were identified as useful serologic markers. Three high-throughput prototype assays were developed using recombinant proteins to detect antibodies to these viral proteins. Both gp70 and p15E prototype assays demonstrated 100% sensitivity by detecting all Western blot (WB) positive serial bleeds from the XMRV-infected macaques and good specificity (99.5-99.9%) with blood donors. Seroconversion sensitivity and specificity of the p30 prototype assay were 92% and 99.4% respectively.

Conclusions

This study provides the first demonstration of seroconversion patterns elicited by XMRV infection. The nature and kinetics of antibody responses to XMRV in primates were fully characterized. Moreover, key serologic markers useful for detection of XMRV infection were identified. Three prototype immunoassays were developed to detect XMRV-specific antibodies. These assays demonstrated good sensitivity and specificity; thus, they will facilitate large scale epidemiologic studies of XMRV infection in humans.

Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a debilitating disease of unknown etiology that is estimated to affect 17 million people worldwide. Studying peripheral blood mononuclear cells (PBMCs) from CFS patients, we identified DNA from a human gammaretrovirus, xenotropic murine leukemia virus-related virus (XMRV), in 68 of 101 patients (67%) as compared to 8 of 218 (3.7%) healthy controls. Cell culture experiments revealed that patient-derived XMRV is infectious and that both cell-associated and cell-free transmission of the virus are possible. Secondary viral infections were established in uninfected primary lymphocytes and indicator cell lines after their exposure to activated PBMCs, B cells, T cells, or plasma derived from CFS patients. These findings raise the possibility that XMRV may be a contributing factor in the pathogenesis of CFS.

Small-molecule activators of RNase L with broad-spectrum antiviral activity

RNase L, a principal mediator of innate immunity to viral infections in higher vertebrates, is required for a complete IFN antiviral response against certain RNA stranded viruses. dsRNA produced during viral infections activates IFN-inducible synthetases that produce 5'-phosphorylated, 2',5'-oligoadenylates (2-5A) from ATP. 2-5A activates RNase L in a wide range of different mammalian cell types, thus blocking viral replication. However, 2-5A has unfavorable pharmacologic properties; it is rapidly degraded, does not transit cell membranes, and leads to apoptosis. To obtain activators of RNase L with improved drug-like properties, high-throughput screening was performed on chemical libraries by using fluorescence resonance energy transfer. Seven compounds were obtained that activated RNase L at micromolar concentrations, and structure-activity relationship studies resulted in identification of an additional four active compounds. Two lead compounds were shown to have a similar mechanistic path toward RNase L activation as the natural activator 2-5A. The compounds bound to the 2-5A-binding domain of RNase L (as determined by surface plasmon resonance and confirmed by computational docking), and the compounds induced RNase L dimerization and activation. Interestingly, the low-molecular-weight activators of RNase L had broad-spectrum antiviral activity against diverse types of RNA viruses, including the human pathogen human parainfluenza virus type 3, yet these compounds by themselves were not cytotoxic at the effective concentrations. Therefore, these RNase L activators are prototypes for a previously uncharacterized class of broad-spectrum antiviral agents.

An infectious retrovirus susceptible to an IFN antiviral pathway from human prostate tumors

We recently reported identification of a previously undescribed gammaretrovirus genome, xenotropic murine leukemia virus-related virus (XMRV), in prostate cancer tissue from patients homozygous for a reduced activity variant of the antiviral enzyme RNase L. Here we constructed a full-length XMRV genome from prostate tissue RNA and showed that the molecular viral clone is replication-competent. XMRV replication in the prostate cancer cell line DU145 was sensitive to inhibition by IFN-beta. However, LNCaP prostate cancer cells, which are deficient in JAK1 and RNase L, were resistant to the effects of IFN-beta against XMRV. Furthermore, DU145 cells rendered deficient in RNase L with siRNA were partially resistant to IFN inhibition of XMRV. Expression in hamster cells of the xenotropic and polytropic retrovirus receptor 1 allowed these cells to be infected by XMRV. XMRV provirus integration sites were mapped in DNA isolated from human prostate tumor tissue to genes for two transcription factors (NFATc3 and CREB5) and to a gene encoding a suppressor of androgen receptor transactivation (APPBP2/PAT1/ARA67). Our studies demonstrate that XMRV is a virus that has infected humans and is susceptible to inhibition by IFN and its downstream effector, RNase L.

Regulation of chemokine mRNA stability by lipopolysaccharide and IL-10

IL-10 has been reported to inhibit the expression of LPS-induced proinflammatory cytokines and chemokines by altering the rate of specific mRNA decay although the molecular target(s) for its action remain unknown. In the present study, using primary peritoneal exudate macrophages and a cell culture model in which a tetracycline-responsive promoter controls transcription of CXC ligand 1 (KC) mRNA, we demonstrate that LPS promotes a time-dependent increase in KC mRNA stability. Although IL-10 had no direct effect on mRNA decay, this treatment antagonized the stabilizing action of LPS. The mechanisms involved were further explored using a cell-free mRNA degradation system. A 5'-capped, polyadenylated in vitro transcript derived from the 3'-untranslated region of KC mRNA exhibited time-dependent decay in the presence of protein extracts prepared from untreated RAW264.7 macrophages. Extracts prepared from LPS-treated RAW264.7 cells had reduced decay activity and this change was antagonized if the cells were costimulated with IL-10. A substrate in which the AU-rich element motifs were mutated exhibited minimal decay that did not vary using extracts prepared from cells treated with LPS or LPS and IL-10. A nonadenylated RNA substrate was also degraded and that activity was diminished by LPS. In concert, these findings demonstrate that KC mRNA stability is regulated by LPS-induced alterations in activities that govern both deadenylation and degradation of the mRNA body. The effects of IL-10 on KC mRNA stability reflect antagonism of the response to LPS.

Gastro-duodenal mucosal changes associated with low-dose aspirin therapy: a prospective, endoscopic study

OBJECTIVES

The association of low-dose aspirin use and gastro-intestinal bleeding is well described. However, the gastroduodenal mucosal changes associated with low-dose aspirin therapy have not been properly evaluated. We undertook a prospective, endoscopic study to evaluate gastro-duodenal mucosal lesions produced by low-dose aspirin.

METHODS

Forty-seven patients with non-hemorrhagic cerebral infarct or transient ischemic attacks and normal upper gastrointestinal endoscopy were randomized to receive either enteric-coated (n=25) or plain (n=22) aspirin (150 mg/day). Follow-up endoscopy was done at 2, 4 and 8 weeks; gastro-duodenal mucosal lesions, if present, were scored. Forty-seven patients with hemorrhagic infarct who were not treated with aspirin served as controls.

RESULTS

Twenty eight (60%) of 47 patients receiving aspirin had mucosal lesions; stomach alone was the most frequent site (32%), followed by both stomach and duodenum (23%). Frequency of mucosal changes in the stomach at 8 weeks (19%) was significantly lower (p<0.05) than those at 2 weeks (53%) and 4 weeks (55%). Coated (56%) and plain (63.6%) aspirin induced mucosal lesions with similar frequency.

CONCLUSION

Administration of low-dose aspirin, either plain or enteric-coated, induces endoscopic gastro-duodenal mucosal lesions in a large majority of patients. The frequency of damage decreased after 8 weeks of therapy.

Position and sequence requirements for poly(A) length regulation by the poly(A) limiting element

The poly(A)-limiting element (PLE) is a cis-acting sequence that acts to limit poly(A) tail length on pre-mRNA to <20 nt. Functional PLEs are present in a number of genes, underscoring the generality of this control mechanism. The current study sought to define further the position requirements for poly(A) length regulation and the core sequence that comprises a PLE. Increasing the spacing between the PLE and the upstream 3' splice site or between the PLE and the downstream AAUAAA had no effect on poly(A) length control. However, moving the PLE from the terminal exon to either an upstream exon or intron eliminated poly(A) length control. Poly(A) length control was further evaluated using a battery of constructs in which the PLE was maintained in the terminal exon, but where upstream introns were either deleted, modified, or replaced with a polypyrimidine tract. Poly(A) length control was retained in all cases, indicating that the key feature is the presence of the PLE in the terminal exon. A battery of mutations demonstrated the importance of the 5' pyrimidine-rich portion of the element. Finally, UV crosslinking experiments identified an approximately 62-kDa protein in Hela nuclear extract that binds to a wild-type 23-nt PLE RNA oligonucleotides but not to a mutated nonfunctional form of the element.

Polynucleotide phosphorylase is a component of a novel plant poly(A) polymerase

We have isolated cDNA clones encoding a novel RNA-binding protein that is a component of a multisubunit poly(A) polymerase from pea seedlings. The encoded protein bears a significant resemblance to polynucleotide phosphorylases (PNPases) from bacteria and chloroplasts. More significantly, this RNA-binding protein is able to degrade RNAs with the resultant production of nucleotide diphosphates, and it can add extended polyadenylate tracts to RNAs using ADP as a donor for adenylate moieties. These activities are characteristic of PNPase. Antibodies raised against the cloned protein simultaneously immunoprecipitate both poly(A) polymerase and PNPase activity. We conclude from these studies that PNPase is the RNA-binding cofactor for this poly(A) polymerase and is an integral player in the reaction catalyzed by this enzyme. The identification of this RNA-binding protein as PNPase, which is a chloroplast-localized enzyme known to be involved in mRNA 3'-end determination and turnover (Hayes, R., Kudla, J., Schuster, G., Gabay, L., Maliga, P., and Gruissem, W. (1996) EMBO J. 15, 1132-1141), raises interesting questions regarding the subcellular location of the poly(A) polymerase under study. We have reexamined this issue, and we find that this enzyme can be detected in chloroplast extracts. The involvement of PNPase in polyadenylation in vitro provides a biochemical rationale for the link between chloroplast RNA polyadenylation and RNA turnover which has been noted by others (Lisitsky, I., Klaff, P., and Schuster, G. (1996) Proc. Natl. Acad. Sci. U. S. A. 93, 13398-13403).

A plant poly(A) polymerase requires a novel RNA-binding protein for activity

We have purified a novel factor (PAP-III) that is a component of a multisubunit poly(A) polymerase from pea seedlings. This factor consists of one or more polypeptides with molecular masses of about 105 kDa and of a population of associated RNAs that can serve as substrates for polyadenylation. When these RNAs are separated from the 105-kDa polypeptides, polyadenylation becomes dependent upon exogenously added RNA. This RNA-dependent activity does not require the presence of a polyadenylation signal in the substrate, indicating that the activity under study is a nonspecific polyadenylation activity. One or more of the 105-kDa polypeptides could be cross-linked to the products of polyadenylation labeled with [alpha-32P]ATP and to exogenously added labeled RNAs. Cross-linking of the 105-kDa polypeptides to the products of polyadenylation was not affected by the presence of exogenously added competitors, whereas cross-linking to exogenous RNAs was diminished by excesses of RNA homopolymers. Exogenous RNAs could be polyadenylated by the combination of PAP-I + PAP-III, and this activity was diminished if the binding of the exogenous RNAs to PAP-III was prevented. We conclude from these studies that PAP-III is an RNA binding protein, that polyadenylation by the poly(A) polymerase occurs while the substrate RNAs are associated with this protein, and that the pea poly(A) polymerase can only polyadenylate those RNAs that are associated with PAP-III.

Influence of dietary restriction and soyabean supplementation on the growth of a murine lymphoma and host immune function

A comparative study was made to reveal the influence of caloric restriction with or without soyabean in the diet on the growth of a murine lymphoma, host survival, serum profile of vitamin A and E and immune status of the host. Caloric restriction delayed and inhibited tumour growth and improved host survival; inclusion of soyabean during restriction enhanced this effect. Dietary restriction both in the absence and presence of soyabean improved the proliferative response of peripheral blood lymphocytes. This was accompanied by increased cytolytic activity of peritoneal macrophages and elevation in serum immunoglobulins (IgG and IgM). Levels of vitamins A and E, which is found to be low in tumour bearing animals, decreased further when maintained in the restricted diet without soyabean, but was raised to normal levels following addition of soyabean in the diet. These observations imply that tumour growth is arrested possibly by insufficient nutrition available due to dietary restriction, for actively proliferating tumour cells and by improvement in host immune mechanism in the presence of soyabean in the diet.

Experimental evaluation of preventive and therapeutic potentials of lysozyme

Therapeutic efficacy and preventive role of egg white lysozyme was evaluated in three types of murine ascitic tumours, namely sarcoma 180, Ehrlich's carcinoma, and Dalton's lymphoma. Lysozyme treatment produced regression of tumour growth and improved the life expectancy of the host. Growth of tumour cells treated in vitro with lysozyme prior to transplantation was also affected. In addition, lysozyme was found to have a preventive effect when administered to normal mice. The antitumour activity, therapeutic and preventive, of lysozyme seems to be due to its action on the tumour cell surface as well as on the host-mediated immune response.

Chronic arsenic toxicity from drinking tubewell water in rural West Bengal

Hepatic damage caused by chronic exposure to arsenic has been frequently described. Here we report on 13 patients from West Bengal, India, who consumed large amounts of arsenic in drinking water. An epidemiological investigation of the study area showed evidence of chronic arsenical dermatosis and hepatomegaly in 62 (92.5%) of 67 members of families who drank contaminated water (arsenic level, 0.2-2 mg/l). In contrast, only six (6.25%) of 96 persons from the same area who drank safe water (arsenic level, <0.05 mg/l) had non-specific hepatomegaly, while none had skin lesions. Hepatomegaly occurred in all the 13 patients who were studied in detail, although five had splenomegaly. Biopsy of samples of liver from these patients revealed various degrees of fibrosis and expansion of the portal zone that resembled non-cirrhotic portal fibrosis (NCPF).

Trace elements in the sera of leprosy spectrum

Serum zinc, copper, calcium and magnesium levels were estimated by atomic absorption spectrophotometry in 56 leprosy patients comprising 14 BT, 12 BB, 11 BL and 19 LL. These findings were evaluated in comparison to 42 normal subjects serving as controls. A significant elevation of serum copper was recorded while reduction in zinc, calcium and magnesium was noted throughout the leprosy spectrum. The findings of our study are of considerable importance and need to be taken note of in the light of delineating these alterations to be the cause or effect of the disease.

Levels of glycolytic enzymes in the red blood cells of Australian Aborigines

Blood samples wer collected from three populations of full-blood Aborigines, and twelve different enzymes were assayed in red blood cells. These results were compared with those of Caucasian controls. In the majority of enzymes studied significant differences were observed between the Aboriginal populations and also between individual Aboriginal populations and the Caucasian controls.

Effect of other drugs and chemicals on the degradation of aspirin in vitro: possible extrapolation to in vivo metabolism of aspirin

To assess the possible influence of other drugs and chemicals on the metabolic degradation of aspirin in man, their effect on the serum aspirin esterase activity was determined in vitro. The activation or inhibition of the enzyme as observed with these compounds suggest the possibility that simultaneous ingestion of these drugs with aspirin may influence the pharmacology and toxicity of the analgesic.

Serum aspirin esterase activity in women with habitual aspirin intake

A method for the determination of aspirin esterase activity in serum is described. Sera from 59 pregnant women who were habitual aspirin users were found to have a mean enzyme activity value statistically lower than those of 68 non-pregnant women controls or of 12 pregnant women controls who were either occasional users of the drug or were non-users. The distribution of enzyme activity in the experimental group was also significantly different from that of the control group. It is postulated that the low enzyme activity may further aggravate the injurious effects of high intake of aspirin.

Galactose metabolism in relation to cataract formation in marsupials

Erythrocytic galactokinase and/or galactose-1-phosphate uridyl transferase activity were low in many species of marsupials. However, cataract formation was observed only in pouch-young members of these species when reared on cow's milk. The galactose tolerance of young kangaroos was found to be greatly impaired, but improved rapidly and markedly at the stage of which the definitive structure of the ruminant type of stomach as in adults is formed. The combination of high absorption of galactose and low levels of galactokinase and/or transferase thus appears to determine the predisposition of pouch-young marsupials to galactose cataractogenesis.

Differential immune response to attenuated rubella virus vaccine

Serum samples collected from 18 volunteers 1, 2, and 3 months after vaccination with Cendehill strain of attenuated rubella virus vaccine were fractionated on a Sephadex G-200 column to test for immunoglobulin M (IgM) antibody. Seventeen of the 18 had demonstrable IgM antibody in serum collected 1 month postvaccination whereas only 5 and 3 had IgM antibody 2 and 3 months, respectively, post-inoculation. The geometric mean titers of hemagglutination-inhibiting antibody in the 19S fraction were 38, 7, and 6 at 1, 2, and 3 months after vaccination, whereas the corresponding 7S titers were 29, 53, and 57, respectively. Four other seronegative volunteers vaccinated with Cendevax were tested serially for total antibody only in whole blood obtained by finger pricks. Three of them showed appearance of antibody between 14 and 17 days and one between 17 and 21 days. It appears that vaccine-induced immune response is similar to natural infection especially with regard to the time of appearance of antibody and the relative proportions of IgM and IgG antibody thus produced.