The Effect of Different Species of Eimeria with Clostridium perfringens on Performance Parameters and Induction of Clinical Necrotic Enteritis in Broiler Chickens

Necrotic enteritis (NE) is a common disease that causes great economic loss to the broiler industry due to mortality and reduced performance. Although Clostridium perfringens (CP) is a necessary component of this disease, coccidia species are a well-defined predisposing factor that exacerbates the condition. Different Eimeria species have been reported to influence NE to different degrees. In a pair of experiments, six different Eimeria species were evaluated in the presence and absence of C. perfringens. Male broiler chicks were housed in battery cages for the duration of both experiments. Feed conversion, body weight gain, and NE mortality were reported in both experiments. Experiment 1 challenged birds with E. maxima, E. acervulina, E. tenella, E. necatrix, and E. brunetti at day 13 and subsequently inoculated birds with CP on days 18, 19, and 20. In the second experiment, E. maxima, E. acervulina, E. tenella, and E. praecox were inoculated on day 15 and challenged with CP on days 17, 18, 19, 20, 21, and 22 of the experiment. In the first experiment, E. acervulina, E. brunetti, E. maxima, and E. necatrix with the addition of CP all stimulated necrotic enteritis mortality. In the second experiment, E. praecox had minimal impact on performance during the challenge (14-23 days) while E. maxima + CP decreased body weight gain and increased mortality compared to the CP alone control. Eimeria maxima had the highest mortality (21.9%) in this experiment followed by E. acervulina (6.3%). The remaining Eimeria with added CP in the second experiment did not induce NE mortality. While the challenge with CP alone did not induce mortality, feed conversion was increased compared to the unchallenged control group. When using isolated Eimeria species in these experiments, disturbances created by E. brunetti and E. maxima resulted in the most-severe challenges. These experiments highlight the NE risk of these species of Eimeria and give insight into how other species interact with the host in a controlled CP challenge model.

Coexpression of granulocyte colony stimulating factor and its receptor in primary ovarian carcinomas

Immunohistochemistry was used to determine the expression of granulocyte colony-stimulating factor (G-CSF) and its receptor (G-CSFR) in primary ovarian carcinomas. The expression of G-CSFR was observed in the malignant cells of each of the 46 primary carcinomas examined; G-CSF was coexpressed in both the malignant epithelial cells and the stroma of 56.5% of the specimens. Thus the majority of ovarian carcinomas harbor both potential autocrine and paracrine G-CSF axes. In 37% of the samples, G-CSF was expressed only within stromal cells, suggesting that only a potential paracrine system is in place. In a preliminary, retrospective, evaluation, the survival of patients whose tumors expressed only the apparent paracrine loop was significantly worse than patients whose tumors expressed both potential autocrine and paracrine G-CSF-based regulatory loops (14.5 vs. 42.5 months, respectively). Studies on the potential function of G-CSF were performed using the G-CSFR-expressing OVCAR-3 ovarian carcinoma line. As a single agent, rhG-CSF failed to stimulate [3H]-thymidine incorporation in these cells, but enhanced the mitogenic action of epidermal growth factor (EGF) in a dose-dependent manner. Thus, potential autocrine and/or paracrine loops involving G-CSF and its receptor occur in over 90% of primary ovarian carcinomas, and may act to modulate the action of growth factors.

Latent membrane protein 1 associated signaling pathways are important in tumor cells of Epstein-Barr virus negative Hodgkin's disease

The latent membrane protein 1 (LMP1) oncogene of Epstein-Barr virus (EBV) is selectively expressed in the Reed-Sternberg (RS) cells of EBV-associated Hodgkin's disease (HD). However, no differences in clinical presentation and course are found between EBV positive and EBV negative forms of HD suggesting a common pathogenetic mechanism. We have studied the LMP1 associated signaling pathways and their dominant negative inhibition in the myelomonocytic HD-MyZ and the B-lymphoid L-428 HD cell lines. In both EBV negative cell lines expression of LMP1 is associated with the formation of multinuclear RS cells. Dominant negative inhibition of NF-kappa B mediated signaling at the step of I kappa B-alpha phosphorylation results in increased cell death with only a few typical RS cells resistant to overexpression of the dominant negative inhibitor I kappa B-alpha-N delta 54. However, dominant negative inhibition of NF-kappa B mediated signaling at the early step of TRAF2 interaction results in the formation of multinuclear cells in both cell lines and, in addition, in clusters of small mononuclear cells in the HD-MyZ cell line. In HD-MyZ cells overexpression of the powerful JBD-inhibitor of the JNK signal transduction pathway is restricted to small cells and never observed in RS cells. These small cells undergo apoptosis as shown by the TUNEL technique. Apoptosis of small cells is still observed after co-transfection of JBD and LMP1 but in addition a few apoptotic HD-MyZ cells with large fused nuclear masses are identified suggesting that specific inhibition of JNK leads also to apoptosis of LMP1 induced RS cells. Thus, activation of the JNK signaling pathway is also important in the formation of Reed-Sternberg cells. Our findings are consistent with a model where all three LMP1 associated functions, i.e. NF-kappa B mediated transcription, TRAF2 dependent signaling, and c-Jun activation act as a common pathogenetic denominator of both EBV negative and EBV positive HD.

Sequence polymorphisms between latent membrane proteins LMP1 and LMP2A do not correlate in EBV-associated reactive and malignant lympho-proliferations

The latent membrane proteins LMP1 and LMP2A are co-expressed in most malignancies associated with Epstein-Barr virus (EBV). In contrast with the transforming LMP1 oncoprotein, LMP2A is expressed in lymphocytes of healthy EBV carriers and considered to maintain viral latency. Critical for these LMP2A functions are a transmembranous epitope recognized by specific cytotoxic T lymphocytes (CTLs) and the N-terminal immunoreceptor tyrosine-based activation motif (ITAM), blocking B-cell receptor signaling. To characterize ITAM and CTL motifs of LMP2A and to correlate them with C-terminal variants of LMP1 including the 30-bp deletion variant (LMP1delta), comparative sequence analysis was performed on 76 samples from patients with reactive and malignant lympho-proliferation (infectious mononucleosis, n=21; tonsillar hyperplasia, n=16, chronic lympho-proliferation, n = 9; Hodgkin's disease, n = 8; Non-Hodgkin's lymphoma, n = 5; AIDS-related large-cell lymphoma, n=17). The CTL motif was conserved in all but 2 cases (C426-->S). The ITAM motif was characterized by strictly conserved YXXL sequences in all cases, with a sequence polymorphism in between. The B95.8 prototype was found in 17% (13/76) of cases, while in 72% a variant with 3 point mutations (166796 C-->A, 166805 C-->A, 166810 C-->T) was detected; 11% had 1 or 2 of these mutations in addition to G-->A at 166793. In the C terminus of LMP1, a hypervariable region including LMP1delta was described in 61% of cases. There was no significant association of a particular LMP2A variant with either malignant phenotype or LMP1delta, demonstrating that the functional domains of LMP2A are conserved and that the sequence polymorphisms in LMP1 and LMP2A are independent.

Epstein-Barr virus related hemophagocytic syndrome in a T-cell rich B-cell lymphoma

We report the case of a 30-year-old woman who presented with an EBV related hemophagocytic syndrome. After a few months she developed a T-cell rich B-cell non-Hodgkin's lymphoma with liver involvement. Serological data demonstrated a reactivation of the EBV infection. Tumor progression with liver involvement occurred during treatment with conventional chemotherapy. Tumor reduction and disappearance of all masses was seen after starting high-dose sequential chemotherapy, followed by an autologous peripheral blood progenitor transplantation LMP-1 could be amplified in the tumor material by PCR technology, but no LMP-1 expression could be found in the few malignant B-cells with Reed-Sternberg morphology. Sequence analysis of the carboxy terminal of the LMP-1 region revealed the naturally occurring 30 bp deletion variant of the LMP-1 with multiple point mutations within the NF kb region. Since LMP-1 was not expressed in the malignant tumor cells, no evidence could be found, that EBV participated in the tumorigenesis of this case.

Carboxy terminal variants of Epstein-Barr virus-encoded latent membrane protein 1 during long-term human immunodeficiency virus infection: reliable markers for individual strain identification

To assess the frequency and molecular polymorphism of malignancy-associated latent membrane protein 1 (LMP1) variants in human immunodeficiency virus type 1 (HIV-1) infection, 94 B-lymphoblastoid cell lines spontaneously derived from peripheral blood mononuclear cells (PBMC) and 30 PBMC samples at seroconversion and later (mean, 55 months) were analyzed by longitudinal comparative sequence analysis in 8 patients progressing to non-Hodgkin's lymphoma (AIDS-NHL), 7 patients to opportunistic infections, and 2 patients with long-term asymptomatic HIV-1 infection. The sequence polymorphism in the C-terminus of LMP1 was characteristic for strains harbored by individual patients, with high fidelity for strain identification. In 14 of the 17 patients, two different but characteristic LMP1 variants were identified. At HIV seroconversion in 8 of 15 patients, a 30-bp deletion (LMP1Delta) was present. Though serial analysis revealed a shift to LMP1Delta in some individuals, statistical analysis of the cohort does not support the hypothesis that accumulation of LMP1Delta variants in PBMC accounts for their observed high incidence in AIDS-NHL.

Molecular analysis of critical sequences within the EBNA-2 type 1 gene from Epstein-Barr virus isolates from patients with infectious mononucleosis, tonsillar hyperplasia, and HIV infection

EBNA-2 is the first protein to be detected after infection of primary B lymphocytes by Epstein-Barr virus (EBV) and plays an essential role as transcriptional activator in EBV-induced lymphocyte transformation. We analysed by PCR and sequencing regions of the EBNA-2 type 1 gene from isolates from 13 children with infectious mononucleosis (IM), 6 children with tonsillar hyperplasia (TH), and 9 patients with HIV infection followed longitudinally. We found in all three groups of patients frequent non-silent point mutations at positions 48990, 48991, 49021, 49057, 49083, 49089, 49091, 49113, 49119, 49140, 49156, and a triplet insertion at position 49136. While 4 out of 13 samples from patients with IM showed a mosaic pattern suggesting co-existence of more than 1 substrain of EBNA-2 type 1, none of the samples from TH showed this pattern consistent with substrain selection during clinical latency. No sequence changes were noted over time in samples derived from patients with HIV infection. We conclude that in analogy to the coexistence of several subtypes of EBNA-1 in healthy EBV carriers, samples from IM can harbor more than one subtype of the EBNA-2 type 1 gene.

The 30-bp deletion variant of Epstein-Barr virus-encoded latent membrane protein-1 prevails in acute infectious mononucleosis

To assess the frequency of malignancy-associated 30-bp deletion variants of the latent membrane protein 1 (LMP-1) in benign conditions, a comparative sequence analysis was done using samples from 20 American children with acute infectious mononucleosis and 16 Swiss children with chronic tonsillar hyperplasia. The 30-bp deletion variant (LMP-1-del) was present in 66% of patients (12/20 with infectious mononucleosis and 12/16 with tonsillar hyperplasia). Two additional patients had a 3-bp deletion and an inframe insertion of 18 nucleotides, respectively. All but 1 isolate had numerous nonsilent point mutations. These data identify a hypervariable region within the C-terminus of LMP-1, in a domain required for maximal stimulation of NF-kappaB activity. These data demonstrate that LMP-1-del variants are frequent in acute infectious mononucleosis and tonsillar hyperplasia and identical to those observed in Epstein-Barr virus-associated AIDS-related lymphoma.

Selective outgrowth of a posttransplant B-immunoblastic lymphoma expressing a latent membrane protein-1 deletion variant

BACKGROUND

Posttransplant lymphoproliferative disorders are generally associated with Epstein-Barr virus (EBV) and are of B cell origin. We report the case of a B-immunoblastic lymphoma that developed in a pretransplantation EBV-seronegative woman 4 months after kidney transplant from her HLA-haploidentical brother. The patient successfully underwent immunotoxin therapy for lymphoma and has been in remission for 36 months.

METHODS

Latent EBV genomes were identified by polymerase chain reaction, and the purified amplification products were directly sequenced with [35S]dATP.

RESULTS

Molecular analysis of the latent membrane protein (LMP)1 oncogene of EBV, which was expressed in most tumor cells, revealed a 30-base pair deletion. No wild-type LMP1 sequences were found. Analysis of peripheral blood mononuclear cells from the EBV-seropositive donor showed the presence of both the LMP1 deletion variant and the wild-type sequence. The LMP1 deletion variant and the wild-type sequence were also identified within peripheral blood mononuclear cells of the EBV-seroconverted kidney recipient 20 months after lymphoma therapy.

CONCLUSION

This pattern is consistent with a natural growth advantage of B cells expressing the LMP1 deletion variant in the immunocompromised host.

Deletion variants within the NF-kappaB activation domain of the LMP1 oncogene in acquired immunodeficiency syndrome-related large cell lymphomas, in prelymphomas and atypical lymphoproliferations

The latent membrane protein 1 (LMP1) oncogene of Epstein Barr virus (EBV) is expressed in tumor cells of acquired immunodeficiency syndrome (AIDS) related lymphomas, HIV-negative, EBV-associated malignant lymphoproliferations, nasopharyngeal carcinoma, as well as in reactive immunoblasts of infectious mononucleosis. Naturally occurring LMP1 deletion variants (LMP1-del), characterized by clustered mutations and a distinct 30 base pair deletion within the carboxy terminal domain of LMP1, essential for maximal NF-kappaB stimulation, have been identified in the same conditions. These variants prevail in AIDS-related lymphomas, and are associated with clinically aggressive behaviour in HIV-negative lymphomas, and are frequent in prelymphomatous and reactive states. Functional studies showing a growth advantage of cells infected by these variants may explain the accumulation of LMP1-del in these entities. In the carboxy terminal NF-kappaB activation domain of LMP1, evidence of a hypervariable region close to the highly conserved 23 outermost amino acids essential for malignant transformation, may reflect the natural selection of growth promoting variants involved in signalling pathways. The prevalence of the same mutational pattern in AIDS-related lymphoma as well as in hyperplastic reactive states and prelymphomas supports the hypothesis that these variants confer a growth advantage manifested under impaired cellular immunity.

Natural 30 base pair and 69 base pair deletion variants of the LMP1 oncogene do stimulate NF-kappaB-mediated transcription

An increasing number of reports shows a link between the Epstein-Barr virus (EBV) and lymphoid neoplasia. The latent membrane protein 1 (LMP1) is likely to play a determinant role in this process since this EBV encoded protein has oncogenic properties and is usually expressed in EBV-associated lymphoproliferative diseases (LPD), except Burkitt's lymphoma. We previously identified in LPD patients mutational hot spots and a 30 bp or 69 bp deletion in the LMP1 gene region coding for the C-terminal domain. These deletions are located in an area shown to be important for the activation of the transcription factor NF-kappaB. These findings lead us to test whether these natural deletion variants may have a functional effect. We measured the stimulation of their activity using a luciferase reporter plasmid containing NF-kappaB responsive elements. We tested the NF-kappaB inducing activity of four naturally occurring LMP1 deletion variants. Our results show that these deletion variants activate NF-kappaB to the same level as the wild-type form, indicating that the crucial residues for NF-kappaB activation are conserved among the variants isolated and lie within the last 32 amino acids of the C-terminal domain of the LMP1 oncogene.

Epstein-Barr virus-associated persistent polyclonal B-cell lymphocytosis with a distinct 69-base pair deletion in the LMP1 oncogene

Epstein-Barr virus (EBV) genomes have been detected in peripheral blood lymphocytes (PBL) of patients with persistent polyclonal B-cell lymphocytosis (PPBL). This is consistent with the hypothesis that latent EBV infection is involved in the pathogenesis of this disorder. Two EBV-encoded proteins expressed in viral latency are the latent membrane proteins 1 and 2A (LMP1 and LMP2A). We have studied the LMP1 oncogene and the LMP2A gene in a female patient with PPBL and her five siblings. A cell line derived from peripheral blood lymphocytes (PBL) of the patient was also analyzed. A distinct 69-base pair deletion was identified within the carboxy terminal NF-kappa B activation domain of the LMP1 oncogene in PBL of the patient and in the cell line, whereas none of the siblings harbored this deletion. The tyrosine-signaling motif and the HLA A2.1 epitope of the LMP2A gene were wild type in the patient and all siblings. The presence of a 69-base pair deletion variant of the LMP1 oncogene within the lymphocytes of a PPBL patient but absence of this deletion variant in the unaffected siblings suggests a direct implication of altered LMP1 oncoprotein-dependent function in the pathogenesis of PPBL.

Expression of the LMP1 oncoprotein in the EBV negative Hodgkin's disease cell line L-428 is associated with Reed-Sternberg cell morphology

The latent membrane protein 1 (LMP1) oncogene is one of the major proteins synthesized by the Epstein-Barr virus (EBV) and is expressed in Reed-Sternberg (RS) cells of EBV-associated Hodgkin's disease (HD). We have studied the effect of this oncoprotein on the formation of RS cells in the EBV-negative HD cell lines L-428 and KM-H2 as well as on the formation of multinucleated cells in the mononuclear human embryonic kidney cell line 293. LMP1 prototype (B95-8) and its naturally occurring carboxy terminal 30 base pair deletion variant LMP1-del were transfected into the cell lines and cytocentrifuge preparations were analysed after 24, 48, 72, 144, 216, and 240 h. While no oncoprotein expression was seen in the KM-H2 cell lines, expression of LMP1 and LMP1-del was observed in the L-428 and 293 cell lines. In the HD cell line L-428 oncoprotein expression was infrequent but when observed was very strong and preferentially associated with multinucleated RS cell morphology (71% of LMP1 positive cells). This is in contrast with the untransfected or transfected but not expressing cells where intermediate mononuclear elements predominated over multinucleated RS cells (< 3%). Frequent oncoprotein expression was observed in the 293 cells and again was associated with multinuclearity. These LMP1 expressing 293 giant cells showed strong expression of ICAM-1(CD54), not detectable in the untransfected cells. In the LMP1-del transfectants giant cells with more than four nuclei were frequently observed. However, giant cells were much less frequent in 293 cells transfected with the amino terminal deletion variant of LMP1 or the lytic form of LMP1, known to induce low NF-kappa B activation compared to the LMP1 prototype. Therefore, LMP1 mediated NF-kappa B activation appears to be involved in polycaria formation. The strong association of LMP1 expression with multinuclearity in a genetically unstable condition -the L-428 and 293 cells show multiple chromosomal abnormalities-suggests that this oncoprotein including its naturally occurring carboxy terminal deletion variant promote the formation of multinuclear cells, in particular of RS cells in EBV-associated HD.

Miliary tuberculosis in a patient with Epstein-Barr virus-associated angioimmunoblastic lymphadenopathy

A 74-year-old woman developed angioimmunoblastic lymphadenopathy (AILD) with involvement of intra-abdominal and retroperitoneal lymph nodes. Southern blot analysis showed germline configuration of the JH genes and an oligoclonal pattern of the TcR beta genes. The immunoblasts were of B-cell phenotype and often expressed the CD30 antigen and the latent membrane protein 1 (LMP1) oncogene. Six nonsilent point mutations were identified near the 3' end of the LMP1 gene, leading to a cluster of six amino acid changes within a protein domain needed for maximal NF-kappa B stimulation. After a clinical remission of 8 months the patient relapsed with generalized lymphadenopathy and died secondary to tuberculosis. The oligoclonal rearrangements of the TcR beta genes may reflect an unsuccessful cellular immune response to Mycobacterium tuberculosis or an HLA-restricted T-cell response to B-immunoblasts expressing mutated viral antigens. A positive percutaneous tuberculin test observed 6 months prior to the onset of AILD is in favor of the first possibility.

Deletion variants within the NF-kappa B activation domain of the LMP1 oncogene prevail in acquired immunodeficiency syndrome-related large cell lymphomas and human immunodeficiency virus-negative atypical lymphoproliferations

This sequencing study of 17 acquired immunodeficiency syndrome-related lymphomas (9 primary brain, 8 systemic) and 8 human immunodeficiency virus-negative atypical lymphoproliferations expressing large amounts of the latent membrane protein 1 (LMP1) of Epstein-Barr virus was performed to characterize the carboxy terminal NF-kappa B activation domain of LMP1 at the molecular level in an immunocompromised host. In-frame deletions within the NF-kappa B activation domain were identified in all but 2 primary brain lymphomas, 4 systemic lymphomas, and 4 atypical lymphoproliferations, ie, in 60% of cases. In addition, non silent point mutations (range 1 to 5, mean 3.3) were detected in all cases. Although all changes occurred within the first 100 nucleotides of the carboxy terminal NF-kappa B activation domain--a critical sequence for the protein half-life--not a single point mutation was found in the remaining 62 nucleotides, necessary for malignant transformation. Such a clustering of nonrandom sequence variations, associated with a high oncoprotein expression in immunocompromised hosts, suggests that this part of the LMP1 oncogene behaves as a hypervariable region with natural selection of growth-promoting variants through prolongation of the protein half-life.

Mutations in the fusion peptide and heptad repeat regions of the Newcastle disease virus fusion protein block fusion

Nonconservative mutations were introduced by site-specific mutagenesis into the fusion peptide and the adjacent heptad repeat region of the fusion protein of Newcastle disease virus in order to determine the role of both regions in the fusion activity of the protein. Mutations in both regions that allowed for proper folding and intracellular transport of the protein blocked the fusion activity of the protein when assayed in the presence of the hemagglutinin-neuraminidase protein.

The role of the amino terminus of F1 of the Newcastle disease virus fusion protein in cleavage and fusion

Phenylalanine is the amino acid at the amino terminus of the F1 protein of all paramyxovirus fusion proteins with the exception of the avirulent strains of Newcastle disease virus, which have a leucine residue in this position (Toyoda et al. (1989) Virology 169, 273-282). To explore the role of this phenylalanine in the fusion activity of the protein, this residue, amino acid 117 in the fusion protein sequence, was changed to leucine (F117L) or to glycine (F117G) by site-specific mutagenesis while maintaining the cleavage site sequence of virulent strains of NDV. While both wild-type and the F117G protein were proteolytically cleaved and F1 was detected, the F117L protein was not cleaved. In the presence of the HN protein, both wild-type F and F117G proteins stimulated fusion, but the F117L protein was inactive in fusion. However, incubation in trypsin activated the fusion activity of the protein. Thus the phenylalanine at the amino terminus of the F1 component of the fusion protein is not required for the fusion activity of the protein. The presence of a leucine at this position blocks cleavage even though the cleavage site sequence is unchanged.

Retroviral expressed hemagglutinin-neuraminidase protein protects chickens from Newcastle disease virus induced disease

The hemagglutinin-neuraminidase (HN) gene and the phosphoprotein (P) gene of Newcastle disease virus (NDV) were inserted into a replication competent avian leukosis virus vector. The expression of the HN gene from this vector in chick embryo cells has been previously reported. The P gene is also expressed from this vector in chick embryo cells. The retroviruses were used to immunize 4-week-old chickens. Birds receiving the virus containing the HN gene developed low levels of serum HI titers and NDV neutralization titers. Upon challenge, all birds vaccinated with the HN gene containing virus were protected from disease but not viral infection and replication. In contrast, birds immunized with the P gene containing retrovirus developed more severe clinical signs of disease earlier than birds receiving no immunization or retrovirus alone. The results obtained with the HN gene may have potential application to reducing disease due to NDV genetically engineered vaccines.

Mature, cell-associated HN protein of Newcastle disease virus exists in two forms differentiated by posttranslational modifications

Characterization of the posttranslational modifications of the mature, cell-associated hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) revealed that the HN protein exists in two forms differentiated by disulfide bonds and glycosylation. One form, HNa, contains intermolecular disulfide bonds and is endoglycosidase H partially resistant. The other form, HNb, is not linked by disulfide bonds and is endoglycosidase H sensitive. Both forms of the protein are modified with fucose indicating transport to the Golgi membranes. Both forms are detected at the cell surface by monoclonal antibody. Furthermore, both forms are transported to the cell surface with identical kinetics. HNa is incorporated into virions. HNb is not incorporated into virions and is presumably degraded. The cDNA derived from the HN gene was expressed from a retrovirus vector. The majority of the protein expressed was in the nonvirion-associated form b. Evidence is presented that the level of gene expression determines the ratio of the two forms of HN protein. At high levels of expression, the virion-associated form is favored while at low levels of expression the nonvirion-associated form is favored. The results presented have implications for persistent infections as well as expression of viral genes from different vectors.

The P protein and the nonstructural 38K and 29K proteins of Newcastle disease virus are derived from the same open reading frame

The nucleotide sequence of cloned cDNA copies of the mRNA encoding the Newcastle disease virus (NDV), strain AV, phosphoprotein (P) was determined. The sequence of 1443 nucleotides contains one long open reading frame which could encode a protein with a molecular weight of 42,126, and two smaller open reading frames which could encode proteins with molecular weights of 11,178 and 13,935. Full-length cDNA clones were constructed in an SP6 vector, mRNA was transcribed in a cell-free system using the SP6 polymerase, and the mRNA was translated in a wheat germ cell-free extract. The P mRNA directed the synthesis of, primarily, four products. One, with a molecular weight of 53,000 Da, comigrated with authentic P protein made in infected cells and was precipitable with antisera with specificity for the NDV P protein. The other products of the cell-free reaction had molecular weights of 38,000, 29,000 and 12,000. The 29,000- and the 38,000-Da polypeptides were also precipitable with anti-P protein antibody. Using truncated cDNA clones, evidence is presented that the 38,000- and 29,000-Da proteins are derived from initiation at AUG triplets in the same reading frame as the P protein. Infected cells also contain these polypeptides which may be analogous to C proteins of other paramyxoviruses. Thus the NDV P protein mRNA is different than most other paramyxovirus P protein mRNAs which are translated in two different reading frames to yield the P and C proteins.

Identification of the sequence content of four polycistronic transcripts synthesized in Newcastle disease virus infected cells

During infection, the Newcastle disease virus (NDV) genome is transcribed to produce 5 to 7 species of polycistronic messenger RNA (Wilde and Morrison, J. Virol. 51, 71-76) in addition to the well characterized monocistronic messenger RNA. To identify the specific sequences present in each of the polycistronic RNA species, cDNA clones generated by reverse transcription of NDV mRNAs were characterized and used as probes on Northern blots of total NDV cytoplasmic RNA. By this method, it was shown that four of these large RNA species are polycistronic transcripts containing sequences from two genes: one species contains nucleocapsid protein (NP) and phosphoprotein (P) gene sequences; another, P and membrane protein (M) gene sequences; another, M and fusion protein (F0) gene sequences; and another, F0 and hemagglutinin-neuraminidase protein (HN) gene sequences. The existence of these transcripts yields a transcription map order of NP, P, M, F0, HN. The remaining RNA bands may be composed of at least three different polycistronic transcripts, each of which represents transcription through three adjacent genes.

Effects of salsalate (nonacetylated salicylate) and aspirin on serum prostaglandins in humans

Prostaglandin E2 (PGE2), thromboxane B2 (TXB2), and salicylic acid were measured in blood samples from 10 healthy men after administration of antiinflammatory doses of aspirin (3.9 g/day) or salsalate (3.0 g/day). Each medication was given for 3 days, followed by an observation period of 13 days. Plasma salicylate concentrations were slightly, but generally insignificantly, higher during aspirin dosing, although both drugs produced salicylic acid levels in the antiinflammatory range. Serum levels of PGE2 and TXB2, which reflected synthesis of cyclo-oxygenase products by platelets, were minimally affected by salsalate but profoundly suppressed by aspirin. When medication was discontinued, the effects of salsalate on serum PGE2 and TXB2 were readily reversible within 36 h, whereas the recovery from aspirin was still incomplete after 13 days of observation. These results indicate that the two orally administered salicylates have differential effects on prostaglandin synthesis in platelets and may also differ in their therapeutic and adverse effects.

Assembly of viral membranes. I. Association of vesicular stomatitis virus membrane proteins and membranes in a cell-free system

We report here an in vitro system designed to study the interactions of vesicular stomatitis virus (VSV) proteins with cellular membranes. We have synthesized the VSV nucleocapsid (N) protein, nonstructural (NS) protein, glycoprotein (G protein), and membrane (M) protein in a wheat germ, cell-free, protein-synthesizing system directed by VSV 12 to 18S RNA. When incubated at low salt concentrations with purified cytoplasmic membranes derived from Chinese hamster ovary cells, the VSV M andG proteins bind to membranes, whereas the VSV N and NS proteins do not. The VSV M protein binds to membranes in low or high divalent cation concentrations, whereas binding of significant amounts of G protein requires at least 5 mM magnesium acetate concentrations.