Consumo de nutrientes, comportamento ingestivo e desempenho de ovinos alimentados com fenos de gramíneas tropicais em diferentes intervalos entre cortes / Nutrient intake, feeding behavior and performance of sheep fed hay of tropical grasses at different cutting intervals

Objetivou-se avaliar o efeito dos fenos de andropogon, buffel e massai em diferentes intervalos de cortes sob consumo, comportamento ingestivo e o desempenho de ovinos. O delineamento experimental foi inteiramente ao acaso. Os tratamentos foram arranjados em fatorial 3x4 (andropogon, buffel e massai x intervalos entre corte de 21, 35, 49 e 63 dias). A interação entre as gramíneas e os intervalos não foi significativa para nenhuma das variáveis estudadas. Os maiores consumos de matéria seca, proteína bruta, fibra em detergente neutro e lignina ocorreram com uso do feno de massai, 3,62; 0,48; 2,03 e 0,22% do peso vivo, respectivamente. Aos 63 dias de intervalo, foram observados os maiores consumos de lignina e os menores de proteína bruta, 0,20 e 0,42%, respectivamente. O menor ganho médio diário (121,1g/dia) e o menor peso final (17,6kg) foram dos animais alimentados com buffel. Não houve diferença para o tempo de alimentação e o ócio, com tempo médio despendido de 4,5 e 11,7h/dia, respectivamente. Os fenos de massai e andropogon promovem maior consumo de matéria seca e maior desempenho de ovinos em confinamento, enquanto o intervalo entre corte até 63 dias não modifica essas respostas.(AU)

The objective of this study was to evaluate the effect of Andropogon, Buffel and Massai on different intervals cuts of intake, ingestion behavior and sheep performance. The experimental design was completely randomized. The treatments were arranged in 3x4 factorial (Andropogon, Buffel and Massai x cut intervals of 21, 35, 49 and 63 days). The interaction between the grasses and the intervals was not significant for any of the studied variables. The highest intakes of dry matter, crude protein, neutral detergent fiber, acid detergent fiber and lignin were for Massai hay, 3.62; 0.48; 2.03 and 0.22% of the live weight, respectively. At 63 days interval, the highest consumption of lignin and lowest crude protein, 0.20 and 0.42%, respectively, were observed. The lowest daily gain (121.1g/day) and final weight gain (17,6kg) were of Buffel fed animals. There was no difference in feeding time and time, with mean time removed from 4.5 and 11.7h day-1, respectively. Hays of Massai and Andropogon promote greater dry matter intake and performance of sheep in confinement, while the cut intervals up to 63 days does not modify these responses.(AU)

Influence of gender and stress on the volatile sulfur compounds and stress biomarkers production.

BACKGROUND: Stress and menstrual cycle have been described as factors influencing bad breath, as they can alter oral homeostasis and contribute to the production of volatile sulfur compounds (VSC). OBJECTIVE: Considering that the experimenter's and volunteer's gender may influence the volunteer's responses to stress, the aim of this work was to evaluate the influence of stress and gender on the production of VSC and salivary biomarkers. METHODS: The experimental acute stress was induced by the Video-Recorded Stroop Color-Word Test (VRSCWT). The VSC, salivary proteins, and cardiovascular parameters were measured before and after VRSCWT. RESULTS: The VRSCWT induced significant increase in total VSC, hydrogen sulfide, and blood pressure values in men and women. Women presented higher values of both these compounds than men. The increase in systolic blood pressure was more pronounced when subjects were evaluated by an experimenter of the opposite gender. When women were evaluated by a member of the opposite gender, they showed significant increases in salivary alpha-amylase and cortisol compared with baseline values. CONCLUSION: Thus, the results showed that VRSCWT induced acute stress, which increased VSC production, and these effects were shown to be influenced by the gender.

Influence of gender and menstrual cycle on volatile sulphur compounds production.

The menstrual cycle has been pointed out as a factor influencing halitosis. However, this relationship has not yet been clarified. The aim of this study was to evaluate the influence of gender and the menstrual cycle on the production of volatile sulphur compounds (VSC) in women (n=14) across the menstrual cycle, and in men (n=17). Volunteers in good oral and general health were submitted to the evaluation of VSC, salivary flow, cortisol and anaerobic bacteria counts in saliva. Data were compared among groups by Analysis of Variance (alpha=5%). VSC was higher in the menstrual and premenstrual phases when compared with men and the follicular phase (p<0.05). Salivary flow was lower in the menstrual and premenstrual phases when compared with men and the follicular phase (p<0.05). Salivary cortisol was higher in the menstrual phase in comparison with men and the premenstrual and follicular phases (p<0.05). Total salivary protein was higher in men when compared to women (p<0.05) with no differences among menstrual phases (p>0.05). Levels of anaerobic micro-organisms, however, were not different among groups (p>0.05). In conclusion, the production of VSC is influenced by menstrual cycle and protein concentration and salivary flow might be involved in this process.

RD114-pseudotyped retroviral vectors kill cancer cells by syncytium formation and enhance the cytotoxic effect of the TK/GCV gene therapy strategy.

BACKGROUND: Wild-type RD114 virus is capable of generating syncytia during its replication, and it is believed that cell-free viruses direct the fusion of neighboring cells. The RD114 envelope (Env) that mediates this fusion event is now widely used to pseudotype retroviral and lentiviral vectors in gene therapy. Indeed, vectors pseudotyped with RD114 Env are very efficient to transfer genes into human hematopoietic cells, and they are resistant to human complement inactivation. In this study, we have tested the potential of RD114-pseudotyped vectors produced from the FLYRD18 packaging cell line to induce syncytia. METHODS: RD114-pseudotyped vectors produced from the FLYRD18 packaging cells were added on tumor cell lines, and the formation of syncytia was assessed by microscopy after cell fixation and methylene blue staining. The kinetics of syncytium formation was analyzed by time-lapse microscopy. Finally, the cytotoxic effect of RD114-pseudotyped vectors was measured by the MTT assay on tumor cells, and in combination with the TK/GCV strategy. RESULTS: We have found that these vectors were able to mediate cell-to-cell fusion of human tumor cell lines. A few hours after addition of the vector, cells started to aggregate to form syncytia that eventually evolved toward cell death 48 h postinfection. RD114-pseudotyped vectors were very efficient at killing human cancer cells, and they were also able to enhance dramatically the cytotoxic effect of the TK/GCV strategy. CONCLUSIONS: These findings indicate that RD114-pseudotyped vectors used alone, or in combination with a suicide gene therapy approach, have great potential for the treatment of cancer.

The clonal composition of a peptide-specific oligoclonal CTL repertoire selected in response to persistent EBV infection is stable over time.

The TCR repertoire of a peptide-specific HLA A11-restricted CTL response to persistent infection with EBV was followed for a period of 57 mo. Sequencing of TCR V alpha and V beta chains and alanine scanning mutagenesis analysis of 83 CTL clones isolated in five reactivation experiments demonstrated that this repertoire is composed of at least four distinct CTL clonotypes that are constantly reactivated from donor's blood and express structurally heterogeneous TCRs. Target cell recognition and CD8 blocking experiments indicate that the four clonotypes possess different avidity and TCR affinity for the specific Ag. This demonstrates that at least in some individuals a heterogeneous peptide-specific memory CTL repertoire selected by a persistent Ag can be remarkably stable in time and accommodate a range of TCR affinities and T cell avidities. Our results suggest that competition for the specific Ag may be not the major force driving the maintenance of memory CTLs and that the nature of the first antigenic challenge may largely determine the clonal composition of memory.

Epitope-dependent selection of highly restricted or diverse T cell receptor repertoires in response to persistent infection by Epstein-Barr virus.

The T cell receptor (TCR) repertoires of cytotoxic responses to the immunodominant and subdominant HLA A11-restricted epitopes in the Epstein-Barr virus (EBV) nuclear antigen-4 were investigated in four healthy virus carriers. The response to the subdominant epitope (EBNA4 399-408, designated AVF) was highly restricted with conserved Vbeta usage and identical length and amino acid motifs in the third complementarity-determining regions (CDR3), while a broad repertoire using different combinations of TCR-alpha/beta V and J segments and CDR3 regions was selected by the immunodominant epitope (EBNA4 416-424, designated IVT). Distinct patterns of interaction with the A11-peptide complex were revealed for each AVF- or IVT-specific TCR clonotype by alanine scanning mutagenesis analysis. Blocking of cytotoxic function by antibodies specific for the CD8 coreceptor indicated that, while AVF-specific TCRs are of high affinity, the oligoclonal response to the IVT epitope includes both low- and high-affinity TCRs. Thus, comparison of the memory response to two epitopes derived from the same viral antigen and presented through the same MHC class I allele suggests that immunodominance may correlate with the capacity to maintain a broad TCR repertoire.

Identification and characterization of an Epstein-Barr virus-specific T-cell response in the pathologic tissue of a patient with Hodgkin's disease.

Several lines of evidence indicate that an impairment of EBV-specific immune responses may contribute to the pathogenesis of Hodgkin's disease (HD). At present, however, it is not clear whether a defective immunity to EBV is a characteristic restricted to EBV-associated HD cases or a more generalized phenomenon, part of the inherent immune deficiency of HD patients. In this study, we have addressed this issue by analyzing EBV-specific responses in infiltrating T lymphocytes (TILs) from one HD biopsy, where the virus was confined to a small proportion of apparently normal lymphocytes. TIL cultures were established using low amounts of recombinant interleukin 2 and in the absence of specific stimulation, conditions that preferentially induce the proliferation of in vivo activated T cells. An EBV-specific cytotoxic component was revealed by the capacity of these TILs to lyse autologous EBV-positive lymphoblastoid cell lines (LCLs) obtained by spontaneous transformation from the lesion but not HLA-mismatched LCLs and autologous phytohemagglutinin blasts. This cytotoxic activity closely resembled that of EBV-specific memory T cells, which may be reactivated from the blood lymphocytes of healthy donors by in vitro stimulation with autologous LCLs. The use of a panel of appropriately HLA-matched B95.8-transformed LCLs as targets in standard 51Cr release assays revealed EBV-specific cytotoxic responses to be restricted mainly through the A11 and B44 HLA alleles with a minor HLA-A26-restricted component. Using autologous fibroblasts infected with recombinant vaccinia viruses expressing the EBV latent antigens, the TIL culture was shown to recognize latent membrane protein 2 and, to a lesser extent, EBV-encoded nuclear antigen 6. In addition, a strong proliferative response was induced by coculture of TILs with autologous but not with allogeneic LCLs or autologous phytohemagglutinin blasts. Six CD4-positive, EBV-specific T-cell clones were isolated by limiting dilution. The study of cytokine mRNA expression, carried out by reverse transcriptase-assisted PCR, revealed that three of these T-cell clones expressed a Th0 phenotype, whereas 1 had a Th2 phenotype. These findings are consistent with the presence in this HD lesion of an ongoing immune response against EBV-carrying cells and suggest that the complex immune deficiency that characterizes HD patients probably does not include a generalized, constitutional defect of EBV-specific T-cell responses.

Mechanisms of allele-selective down-regulation of HLA class I in Burkitt's lymphoma.

Burkitt lymphomas (BL) that arise in HLA-AII-positive individuals are characterized by selective loss/down-regulation of the HLA AII polypeptide. We have investigated the molecular basis of such down-regulation by comparing 5 pairs of BL lines and Epstein-Barr virus (EBV)-transformed lymphoblastoid cell lines (LCL) derived from the normal B cells of the same individuals. The presence of apparently intact HLA AII genes was confirmed in all 5 BL/LCL pairs by polymerase chain reaction (PCR) typing and by Southern-blot hybridization with HLA A locus-specific probes. Northern-blot analysis with locus- and allele-specific probes revealed a significantly lower expression or absence of AII-specific mRNA in all 5 BL lines compared to the corresponding LCLs. Up-regulation of AII-specific mRNA was achieved by IFN alpha treatment of 2 BL lines with low HLA AII expression (BL-28 and BL-72) while the treatment had no effect in 3 BL lines (WWI-BL, WW2-BL and BL41) that did not express the endogenous gene. HLA AII expression was restored by transfection of the gene in WWI-BL whereas transfectants of BL-41 remained AII-negative. An HLA-AII-promoter-driven chloramphenicol acetyl transferase reporter gene (pAIICAT) was active in WWI-BL but not in BL-41. HLA-AII was expressed in hybrids of BL-41 with an AII-positive LCL, while expression of the endogenous HLA AII gene could not be restored by fusion of BL-41 with an AII-negative LCL, although an adequate set of transcription factors was present in the hybrid. Our results suggest that genetic defects and lack of transcription factors may contribute to the selective down-regulation of HLA AII in BL cells.

T cell responses and virus evolution: loss of HLA A11-restricted CTL epitopes in Epstein-Barr virus isolates from highly A11-positive populations by selective mutation of anchor residues.

Epstein-Barr virus (EBV) is a B lymphotropic herpesvirus of humans that elicits strong HLA class I-restricted cytotoxic T lymphocyte (CTL) responses. An influence of such responses on virus evolution was first suggested by our finding that EBV isolates from the highly HLA A11-positive Papua New Guinea (PNG) population carried a lys-thr mutation at residue 424 of the nuclear antigen EBV-encoded nuclear antigen (EBNA4) that destroyed the immunodominant target epitope for A11-restricted CTL recognition. Here we turn to a much larger population, Southern Chinese, where the A11 allele is again present in over 50% of the individuals. Each of 23 EBV isolates analyzed from this population were also mutated in the EBNA4 416-424 epitope, the mutations selectively involving one of the two anchor residues in positions 2 (417 val-leu) or 9 (424 lys-asp, -arg or -thr) that are critical for A11-peptide interaction. The majority of the Chinese isolates and all 10 PNG isolates also carried mutations affecting positions 1 and 2 of the next most immunodominant A11-restricted epitope, EBNA4 residues 399-408. These changes clearly affected antigenicity since A11-positive lymphoblastoid cell lines (LCLs) carrying these mutant EBV strains were not recognized by A11-restricted CTLs raised against the prototype B95.8 virus. Furthermore, Chinese donors naturally infected with these mutant viruses did not mount detectable A11-restricted CTL responses on in vitro stimulation with autologous LCL cells carrying either the B95.8 or their endogenous EBV strain. In two different highly A11-positive populations, therefore, immune pressure appears to have selected for resident EBV strains lacking immunodominant A11-restricted CTL epitopes.

Epstein-Barr virus (EBV) can immortalize B-cll cells activated by cytokines.

B-type of chronic lymphocytic leukemia (B-CLL) cells are inert to the potent transforming action of Epstein-Barr virus (EBV). The mitogenic action of Staphylococcus aureus Cowan I (SAC), MP6-thioredoxin, and interleukin 2 (IL-2), agents previously shown to induce proliferation in normal as well as in B-CLL cells, lifted this block, and EBV-positive cell lines could be established. It was not possible to establish cell lines of leukemic origin from cultures that were incubated with EBV alone or cytokine mix alone. CLL-cells infected with EBV only, expressed the viral nuclear antigen complex (EBNA), but not the viral latent membrane protein (LMP). They were not activated as measured by cell size and 3H-thymidine incorporation. In contrast, cells incubated with EBV and cytokine mix expressed both EBNA and LMP in parallel with enlargement and increased 3H-thymidine incorporation. These results emphasize that LMP expression is a prerequisite for growth transformation and immortalization and that cytokine activation signals are required for its expression in B-CLLs. Cells incubated with SAC/MP6-thioredoxin/IL-2 did not express any of the viral antigens, but were activated with regard to the mentioned parameters. Nine cell lines were established from six patients. From each of the three patients, we obtained 'twin'-pair lines: one corresponding to the malignant cell and the other to a normal B-lymphoblastoid cell. Thus, malignant and normal B-cell counterparts, from the very same donor, are at hand for comparative studies. The cell lines have been carried out for more than 12 months in culture. We conclude that B-CLL that are refractory to EBV-transformation can be rendered susceptible through in vitro cytokine activation.

Integration of a short Epstein-Barr virus DNA fragment in a B95-8 virus converted Burkitt lymphoma line expressing Epstein-Barr nuclear antigens EBNA2 and EBNA5.

We have analysed the expression of transformation-associated viral antigens, the Epstein-Barr virus (EBV) DNA content and the phenotypic characteristics of two B95-8 virus-converted sublines of the EBV-negative Burkitt's lymphoma (BL) line BL28. The converted lines called E95A-BL28 and E95B-BL28, respectively, differed in their EBV gene expression. The E95B convertant expressed virus-encoded nuclear antigens EBNA1 to -6 and the membrane protein LMP1, but only EBNA2 and EBNA5 were detected by immunofluorescence and immunoblotting in the E95A convertant. Only the entire BamHI W, Y and H regions could be detected in the E95A convertant by hybridization of Southern blots with probes covering the BamHI C, W, Y, H, F, E, K and Nhet regions of the EBV genome. EBV episomes were found to be absent in the E95A convertant as seen by Gardella gels. The E95A convertant retained the phenotypic characteristics of the EBV-negative parental line, and remained highly clonable in agarose. In contrast, expression of EBNA1 to -6 and LMP1 was accompanied by a shift towards a more lymphoblastoid cell line-like phenotype and by loss of agarose clonability in the E95B convertant.

Selective induction of allostimulatory capacity after 5-azaC treatment of EBV carrying but not EBV negative Burkitt lymphoma cell lines.

Epstein-Barr virus (EBV) negative and EBV carrying Burkitt lymphoma (BL) lines that remain phenotypically similar to the in vivo tumor cells (operationally defined group I BLs) express high levels of CD10 and CD77, and lack immunoblastic markers such as CD23 and CD39, and the cell adhesion molecules CD11a, CD18, CD54 and CD58. This cell phenotype is associated with poor stimulatory capacity in allogeneic mixed lymphocytes cultures (MLC) [Avila-Carino et al. Int. J. Cancer 40, 691-697 (1987)] EBV carrying BL lines tend to drift spontaneously towards an immunoblastic phenotype in parallel with up-regulation of six EBV-encoded nuclear antigens (EBNA-2 to -6) and two membrane proteins (LMP-1 and -2). These viral antigens are characteristically expressed in all EBV transformed lymphoblastoid cell lines (LCLs) of normal B cell origin and can be induced in group I BL lines by treatment with the DNA demethylating agent 5-azacytidine (5-azaC) [Masucci et al. J. Virol. 65, 1558-1567 (1989)]. We have now studied the effect of 5-azaC on the induction of allogenic T cell proliferation by three EBV negative (Ramos, BL28 and BL41) and four EBV carrying BL lines (Rael, Eli, Chep and Mutu) which stably express a group I phenotype. Pre-treatment with 4-15 microM 5-azaC had no effect on the EBV negative cells but increased the stimulatory capacity of all four EBV carrying lines. LMP-1 was the only viral antigen regularly induced suggesting that its expression may be required for the increase of allostimulation. This was corroborated by the observation that LMP-1 transfection increased 35-70-fold the stimulatory capacity of Rael cells. The cell adhesion molecule CD54 was the only cellular marker selectively up-regulated in all cell lines with increased stimulatory capacity.

HLA-A11 epitope loss isolates of Epstein-Barr virus from a highly A11+ population.

Cytotoxic T lymphocytes (CTLs) control viral infections by recognizing viral peptides presented by major histocompatibility complex (MHC) class I molecules. Human leukocyte antigen (HLA)-A11-restricted CTLs that recognize peptide residues 416 to 424 of the Epstein-Barr virus (EBV) nuclear antigen-4 frequently dominate EBV-induced responses in A11+ Caucasian donors. This epitope is conserved in type A EBV strains from Caucasians and central African populations, where A11 is relatively infrequent. However, strains from highly A11+ populations in New Guinea carry a lysine-to-threonine mutation at residue 424 that abrogates CTL recognition and binding of the peptide to nascent A11 molecules. The results suggest that evolution of a widespread and genetically stable virus such as EBV is influenced by pressure from MHC-restricted CTL responses.

Multiple HLA A11-restricted cytotoxic T-lymphocyte epitopes of different immunogenicities in the Epstein-Barr virus-encoded nuclear antigen 4.

Epstein-Barr virus (EBV), a ubiquitous herpesvirus, induces potent HLA class I-restricted cytotoxic T-lymphocyte (CTL) responses. Analyses of target antigen choice have shown that the very strong CTL responses which are often observed through the HLA A11 allele map are due almost entirely to a single transformation-associated EBV protein, the nuclear antigen EBNA4. Here, we sought to determine the number and relative immunogenicities of HLA A11-restricted epitopes within this 938-amino-acid protein. An initial screening with a series of recombinant vaccinia virus vectors encoding progressively truncated forms of EBNA4 was followed by peptide sensitization experiments using overlapping 14- or 15-mers from the entire sequence. These two approaches allowed the identification of five epitope regions located between residues 101 and 115, 416 and 429, 396 and 410, 481 and 495, and 551 and 564 of the EBNA4 molecule. CTL preparations from all seven HLA A11-positive donors tested had demonstrable reactivities against the 416-to-429 peptide, whereas reactivities against the other epitopes either tended to be lost on serial passage or, for some of the donors, were never detected. The immunodominance of the 416-to-429 epitope was further supported by peptide dilution assays using polyclonal effectors and by CTL cloning experiments. Analysis of the 416-to-429 region identified the nanomer 416-424 (IVTDFSVIK) as the cognate peptide. This peptide was able to sensitize targets to lysis by A11-restricted CTL clones at concentrations as low as 5 x 10(-14) M.

Antigen processing and presentation by EBV-carrying cell lines: cell-phenotype dependence and influence of the EBV-encoded LMP1.

Burkitt's-lymphoma (BL) lines which have maintained in vitro the tumor-cell phenotype (group-I BLs) are poor antigen-presenting cells (APC), in spite of a relatively high surface expression of MHC class II. In order to investigate the mechanism of this deficiency, we have compared group-I BL lines, their sub-lines which have progressed in vitro towards an LCL-like phenotype (group-III BLs), and EBV-transformed lymphoblastoid cell lines (LCLs), for their ability to bind and process tetanus toxoid (TT). The uptake and internalization of 125I-labelled TT was equivalent in the 3 cell types. Only LCLs and group-III BL lines were able to process the TT, as shown by the identification of discrete proteolytic products after separation of whole-cell extracts in tricine-SDS-polyacrylamide gels, and by the recovery of TCA-soluble radioactivity in the culture supernatant. Processing of TT was induced by expression of the EBV-encoded membrane protein LMP 1 in transfected group-1 BLs. The present findings suggest that the inability of group-1 BLs to act as APC is due to their failure to process exogenous antigens. This function appears to be related to phenotypic properties that can be modulated by the expression of LMP1.

Immune escape by Epstein-Barr virus (EBV) carrying Burkitt's lymphoma: in vitro reconstitution of sensitivity to EBV-specific cytotoxic T cells.

Epstein-Barr virus (EBV) positive Burkitt's lymphoma (BL) cells are markedly less sensitive to EBV-specific cytotoxic T cell (CTL) recognition than EBV-transformed lymphoblastoid cell lines of normal B cell origin. Three features of the BL cell phenotype might contribute to this reduced susceptibility: (i) low expression of cell adhesion molecules, (ii) low expression of HLA class I and selective down-regulation of particular alleles, and (iii) down-regulation of all transformation-associated EBV antigens except EBV-encoded nuclear antigen (EBNA)-1. This study assesses the individual importance of each of these features for immune escape. For this purpose the WW1-BL cell line was used which expresses all the known transformation-associated EBV antigens (EBNA-1 to -6 and latent membrane protein-1 and -2) but which is negative for HLA A11 and for the adhesion molecule leukocyte function associated antigen-3 (LFA-3). Using recombinant vectors, these deficiencies have been sequentially corrected and the cells have been tested for sensitivity to EBV (B95.8 strain)-induced CTL preparations recognizing epitope(s) of EBNA-4 in the context of HLA A11. Expression of HLA A11 alone or in combination with LFA-3 did not sensitize WW1-BL cells to these effectors. Lysis was only achieved when HLA A11 was co-expressed with the B95.8 virus-encoded EBNA-4 protein, and in these circumstances sensitization did not require LFA-3. These results indicate that reconstitution of the relevant HLA-EBV epitope target complex on the cell membrane is sufficient to render BL cells sensitive to virus-specific cytolysis. The requirement for EBNA-4 reconstitution to achieve lysis of the WW1-BL/A11 transfectant suggested that the resident WW1 virus-encoded EBNA-4 protein did not contain the relevant target epitope for HLA A11-restricted recognition. This was confirmed by transferring the WW1 virus isolate into another A11-positive B cell background.

Human papillomavirus genomes in male urethral cells.

Sixty-four samples of urethral cells from male sexual partners of women with genital human papillomavirus (HPV) infection were analyzed for the presence of HPV types 6, 11, 16, and 18 by polymerase chain reaction (PCR) followed by slot blot hybridization. Additional samples from 37 of these subjects were analyzed for the presence of viral cytopathic effects by conventional cytology. By PCR, HPV DNA was detected in 21% (14/64) of samples. By cytology, 16% (6/37) of the samples showed cellular changes consistent with HPV infection. Polymerase chain reaction and cytology results were concordant for presence and absence of HPV in 5 and 28 cases, respectively. Three additional HPV-positive cases were obtained with PCR in the cytologically negative samples. The cytologic abnormalities were found to be associated with the presence of both low-risk HPV types and meatal acetoreactivity. On the contrary, HPV DNA positivity by PCR was unrelated to viral type and peniscopic findings. Urethral HPV infection was detected by PCR in 30% of males with visible penile lesions and in 18% of those without. These results indicate that PCR analysis of urethral samples is a helpful adjunct to cytology for the detection of HPV DNA in absence of cytologic evidence of infection.

Recognition of the Epstein-Barr virus-encoded nuclear antigens EBNA-4 and EBNA-6 by HLA-A11-restricted cytotoxic T lymphocytes: implications for down-regulation of HLA-A11 in Burkitt lymphoma.

Evasion from cytotoxic T-lymphocyte (CTL) surveillance may be an important step in the pathogenesis of Epstein-Barr virus (EBV)-carrying Burkitt lymphoma (BL) as suggested by the consistent down-regulation of all transformation-associated viral antigens, except EBV nuclear antigen 1 (EBNA-1), and of certain HLA class I alleles in BL biopsies and cell lines that maintain the tumor cell phenotype in vitro. The most common HLA class I defect recorded in BL lines is a selective down-regulation of HLA-A11. To gain some insight into the role of HLA-A11 down-regulation in pathogenesis of BL, we have investigated the target specificity of HLA-A11-restricted CTLs derived by stimulation of lymphocytes from three EBV-seropositive individuals with autologous EBV-transformed lymphoblastoid cell lines. Recombinant vaccinia viruses carrying the coding sequences for EBNA-1, -2A, -2B, -5, -3, -4, and -6 (also known as EBNA-1, -2A, -2B, -LP, -3a, -3b, and -3c, respectively) and EBV latent membrane protein 1 were used to induce high levels of expression of the relevant EBV antigen in fibroblasts derived from HLA class I-matched individuals. EBNA-4-expressing fibroblasts were the predominant target of HLA-A11-restricted CTLs in all three donors. A less pronounced and less regular EBNA-6-specific cytotoxic component was found in two of the donors.