Transcriptional map for Newcastle disease virus

Newcastle disease virus genotype VII gene expression in experimentally infected birds

Newcastle disease virus genotype VII (NDV-GVII) is a highly contagious pathogen responsible for pandemics that have caused devastating economic losses in the poultry industry. Several features in the transcription of NDV mRNA, including differentially expressed genes across the viral genome, are shared with that for other single, non-segmented, negative-strand viruses. Previous studies measuring viral gene expression using northern blotting indicated that the NDV transcription produced non-equimolar levels of viral mRNAs. However, deep high-throughput sequencing of virus-infected tissues can provide a better insight into the patterns of viral transcription. In this report, the transcription pattern of virulent NDV-GVII was analysed using RNA-seq and qRT-PCR. This study revealed the transcriptional profiling of these highly pathogenic NDV-GVII genes: NP:P:M:F:HN:L, in which there was a slight attenuation at the NP:P and HN:L gene boundaries. Our result also provides a fully comprehensive qPCR protocol for measuring viral transcript abundance that may be more convenient for laboratories where accessing RNA-seq is not feasible.

Non-gradient and genotype-dependent patterns of RSV gene expression

Respiratory syncytial virus (RSV) is a nonsegmented negative-strand RNA virus (NSV) and a leading cause of severe lower respiratory tract illness in infants and the elderly. Transcription of the ten RSV genes proceeds sequentially from the 3’ promoter and requires conserved gene start (GS) and gene end (GE) signals. Previous studies using the prototypical GA1 genotype Long and A2 strains have indicated a gradient of gene transcription extending across the genome, with the highest level of mRNA coming from the most promoter-proximal gene, the first nonstructural (NS1) gene, and mRNA levels from subsequent genes dropping until reaching a minimum at the most promoter-distal gene, the polymerase (L) gene. However, recent reports show non-gradient levels of mRNA, with higher than expected levels from the attachment (G) gene. It is unknown to what extent different transcript stabilities might shape measured mRNA levels. It is also unclear whether patterns of RSV gene expression vary, or show strain- or genotype-dependence. To address this, mRNA abundances from five RSV genes were measured by quantitative real-time PCR (qPCR) in three cell lines and in cotton rats infected with RSV isolates belonging to four genotypes (GA1, ON, GB1, BA). Relative mRNA levels reached steady-state between four and 24 hours post-infection. Steady-state patterns were non-gradient and genotype-specific, where mRNA levels from the G gene exceeded those from the more promoter-proximal nucleocapsid (N) gene across isolates. Transcript stabilities could not account for the non-gradient patterns observed, indicating that relative mRNA levels more strongly reflect transcription than decay. Our results indicate that gene expression from a small but diverse set of RSV genotypes is non-gradient and genotype-dependent. We propose novel models of RSV transcription that can account for non-gradient transcription.

Newcastle Disease Virus Infection in Quail

Newcastle disease (ND), caused by virulent strains of Newcastle disease virus (NDV), is a devastating disease of poultry worldwide. The pathogenesis of ND in quail is poorly documented. To characterize the ability of virulent NDV strains to replicate and cause disease in quail, groups of 14 two-week-old Japanese quail ( Coturnix japonica) were experimentally inoculated with 10⁸ EID₅₀ (embryo infectious dose 50%) units of 1 of 4 virulent NDV strains: 2 isolated from quail ( N2, N23) and 2 from chickens ( Israel, Pakistan). At day 2 postinfection, noninfected quail (contact group) were added to each infection group to assess the efficacy of virus transmission. Tested NDV strains showed moderate pathogenicity, with highest mortality being 28% for the N2 strain and below 10% for the others. Two N2-inoculated birds showed neurological signs, such as head tremor and ataxia. Microscopic lesions were present in N2-, Israel-, and Pakistan-inoculated birds and consisted of nonsuppurative encephalitis. Contact birds showed no clinical signs or lesions. In both inoculated and contact birds, virus replication was moderate to minimal, respectively, as observed by immunohistochemistry in tissues and virus isolation from oropharyngeal and cloacal swabs. Strains originally isolated from quail resulted in higher numbers of birds shedding in the inoculation group; however, transmission appeared slightly more efficient with chicken-derived isolates. This study shows that virulent NDV strains have limited replicative potential and mild to moderate disease-inducing ability in Japanese quail.

Comprehensive Analysis and Characterization of Linear Antigenic Domains on HN Protein from Genotype VII Newcastle Disease Virus Using Yeast Surface Display System

Circulation of genotype VII Newcastle disease virus (NDV) has posed a great threat for the poultry industry worldwide. Antibodies against Hemagglutinin-neuraminidase (HN), a membrane protein of NDV with critical roles in NDV infection, have been reported to provide chickens protection from NDV infection. In this study, we comprehensively analyzed the in vivo antibody responses against the linear antigenic domains of the HN protein from genotype VII NDV using a yeast surface display system. The results revealed four distinct regions of HN, P1 (1-52aa), P2 (53-192aa), P3 (193-302aa) and P4 (303-571aa), respectively, according to their antigenic potency. Analysis by FACS and ELISA assay indicated P2 to be the dominant linear antigenic domain, with the immunogenic potency to protect the majority of chickens from NDV challenge. In contrast, the P1, P3 and P4 domains showed weak antigenicity in vivo and could not protect chickens from NDV challenge. These results provide important insight into the characteristic of humoral immune responses elicited by HN of NDV in vivo.

Influence of antigen insertion site and vector dose on immunogenicity and protective capacity in Sendai virus-based human parainfluenza virus type 3 vaccines

Recombinant Sendai virus (rSeV) was used as a live, attenuated vaccine vector for intranasal inoculation and mucosal expression of the hemagglutinin-neuraminidase (HN) surface glycoprotein of human parainfluenza virus type 3 (HPIV3). Two vaccine candidates rSeV-HPIV3HN(P-M) and rSeV-HPIV3(F-HN) were constructed in which the HPIV3 HN open reading frame and an additional gene junction was inserted in the P-M and F-HN gene junctions of rSeV, respectively. The rSeV-HPIV3HN(P-M) virus was attenuated compared to rSeV-HPIV3(F-HN) in LLC-MK2 cells, and yet both vaccine candidates grew to similar extents in NHBE cells and in the respiratory tracts of cotton rats. These results suggest that in vitro vector growth in NHBE cells more accurately predicts virus yield in cotton rats than does growth in LLC-MK2 cells. Both vaccine vectors elicited high levels of serum neutralizing antibodies and conferred protection from HPIV3 challenge in cotton rats. Compared to vaccination with a high dose (2,000,000 PFU), intranasal inoculation with a low dose (200 PFU) resulted in a 10-fold decrease in vector growth in the nasal cavity and trachea and a 50-fold decrease in the lungs. However, low-dose vaccination resulted in only modest decreases in anti-HPIV3 antibodies in sera and was sufficient to confer complete protection from HPIV3 challenge. Varying the HPIV3 antigen insertion site and vector dose allowed fine-tuning of the in vivo growth and immunogenicity of rSeV-based vaccines, but all four vaccination strategies tested resulted in complete protection from HPIV3 challenge. These results highlight the versatility of the rSeV platform for developing intranasally administered respiratory virus vaccines.

Highly divergent virulent isolates of Newcastle disease virus from the Dominican Republic are members of a new genotype that may have evolved unnoticed for over 2 decades

A Newcastle disease virus (NDV) outbreak in chickens was reported in the Dominican Republic in 2008. The complete genome of this isolate, chicken/DominicanRepublic(JuanLopez)/499-31/2008 (NDV-DR499-31/08), and the fusion proteins of three other related viruses from the Dominican Republic and Mexico were sequenced and phylogenetically analyzed. Genetically, these four isolates were highly distinct from all other currently known isolates of NDV, and together, they fulfill the newly established criteria for inclusion as a novel genotype of NDV (genotype XVI). The lack of any reported isolation of viruses related to this group since 1986 suggests that virulent viruses of this genotype may have evolved unnoticed for 22 years. The NDV-DR499-31/08 isolate had an intracerebral pathogenicity index (ICPI) score of 1.88, and sequencing of the fusion cleavage site identified multiple basic amino acids and a phenylalanine at position 117, indicating this isolate to be virulent. These results were further confirmed by a clinicopathological assessment in vivo. In 4-week-old chickens, NDV-DR499-31/08 behaved as a velogenic viscerotropic strain with systemic virus distribution and severe necrohemorrhagic lesions targeting mainly the intestine and the lymphoid organs. The clear phylogenetic relationship between the 2008, 1986, and 1947 ancestral viruses suggests that virulent NDV strains may have evolved in unknown reservoirs in the Caribbean and surrounding regions and underlines the importance of continued and improved epidemiological surveillance strategies to detect NDV in wild-bird species and commercial poultry.

Molecular basis of neurovirulence of flury rabies virus vaccine strains: importance of the polymerase and the glycoprotein R333Q mutation

The molecular mechanisms associated with rabies virus (RV) virulence are not fully understood. In this study, the RV Flury low-egg-passage (LEP) and high-egg-passage (HEP) strains were used as models to explore the attenuation mechanism of RV. The results of our studies confirmed that the R333Q mutation in the glycoprotein (G(R333Q)) is crucial for the attenuation of Flury RV in mice. The R333Q mutation is stably maintained in the HEP genome background but not in the LEP genome background during replication in mouse brain tissue or cell culture. Further investigation using chimeric viruses revealed that the polymerase L gene determines the genetic stability of the G(R333Q) mutation during replication. Moreover, a recombinant RV containing the LEP G protein with the R333Q mutation and the HEP L gene showed significant attenuation, genetic stability, enhancement of apoptosis, and immunogenicity. These results indicate that attenuation of the RV Flury strain results from the coevolution of G and L elements and provide important information for the generation of safer and more effective modified live rabies vaccine.

Transcription and replication of nonsegmented negative-strand RNA viruses

The nonsegmented negative-strand (NNS) RNA viruses of the order Mononegavirales include a wide variety of human, animal, and plant pathogens. The NNS RNA genomes of these viruses are templates for two distinct RNA synthetic processes: transcription to generate mRNAs and replication of the genome via production of a positive-sense antigenome that acts as template to generate progeny negative-strand genomes. The four virus families within the Mononegavirales all express the information encoded in their genomes by transcription of discrete subgenomic mRNAs. The key feature of transcriptional control in the NNS RNA viruses is entry of the virus-encoded RNA-dependent RNA polymerase at a single 3' proximal site followed by obligatory sequential transcription of the linear array of genes. Levels of gene expression are primarily regulated by position of each gene relative to the single promoter and also by cis-acting sequences located at the beginning and end of each gene and at the intergenic junctions. Obligatory sequential transcription dictates that termination of each upstream gene is required for initiation of downstream genes. Therefore, termination is a means to regulate expression of individual genes within the framework of a single transcriptional promoter. By engineering either whole virus genomes or subgenomic replicon derivatives, elements important for signaling transcript initiation, 5' end modification, 3' end polyadenylation, and transcription termination have been identified. Although the diverse families of NNS RNA virus use different sequences to control these processes, transcriptional termination is a common theme in controlling gene expression and overall transcriptional regulation is key in controlling the outcome of viral infection. The latest models for control of replication and transcription are discussed.

Effect of inserting paramyxovirus simian virus 5 gene junctions at the HN/L gene junction: analysis of accumulation of mRNAs transcribed from rescued viable viruses

Simian parainfluenza virus 5 (SV5) is a prototype of the Paramyxoviridae family of nonsegmented negative-sense RNA viruses. The single-stranded RNA genomes of these viruses contain a series of tandemly linked genes separated by intergenic (IG) sequences flanked by gene-end (GE) and gene-start (GS) sequences. The viral RNA polymerase (vRNAP) complex is thought to enter the genome at its 3' end, and synthesis of mRNAs is thought to occur by a stop-start mechanism in a sequential and polar manner, with transcriptional attenuation occurring primarily at the intergenic regions. As a result, multiple nonoverlapping mRNA species are generated for each single entry of the vRNAP. To investigate the functions of GE, IG, and GS sequences in transcription, we constructed plasmids containing cDNAs of the full-length SV5 genome in which the gene junction sequences (GE, IG, and GS sequences) located between the hemagglutinin-neuraminidase (HN) and the polymerase (L) genes were replaced with the counterpart sequences from other gene junctions. By using reverse genetics, we recovered viable viruses from each cDNA construct, although their growth characteristics varied. Analysis of the HN and L mRNAs by quantitative RNase protection assay indicated that the ratios of HN to L mRNAs varied over a fourfold range. The alteration of the gene junction sequences also permitted examination of the hypothesized requirement for hexamer nucleotide position of the GS sites. The recovery of infectious viruses with transcription initiation sites that occurred at nucleotide positions 1, 2, 3, 5, and 6 of the hexamer suggest that the requirement is nonstringent.

Structure of the L (polymerase) protein gene of sonchus yellow net virus

The complete nucleotide sequence of the L protein gene of sonchus yellow net virus (SYNV), a plant rhabdovirus, was determined by dideoxynucleotide sequencing of cloned cDNAs derived from the negative-strand genomic RNA. The L protein gene is composed of 6401 nucleotides (nt) located between positions 7158 and 13558 relative to the 3' end of the genomic RNA. Sequence analysis suggests that the complementary mRNA contains a 44 nt untranslated 5' leader sequence preceding an open reading frame of 6348 nucleotides that is capable of encoding a polypeptide of 2116 amino acids with a deduced molecular weight of 241,569 Da. The L protein is positively charged, has a high proportion of the amino acids Leu and Ile, and contains putative polymerase and RNA binding domains. Extended alignment of the SYNV L protein amino acid sequence with those of other nonsegmented negative-strand RNA virus polymerases reveals conservation of sequences within 12 blocks that appear sequentially along the protein. A cluster dendrogram derived from the L protein alignments indicates that SYNV is more closely related to animal rhabdoviruses than to the paramyxoviruses and that the animal rhabdoviruses have diverged less from each other than from SYNV.

Rapid accumulation of measles virus leader RNA in the nucleus of infected HeLa cells and human lymphoid cells

The 3' terminus of the single-stranded, negative-sense genome of the measles virus comprises a 55-nucleotide-long sequence, which is transcribed into a short, positive-sense RNA called the leader sequence. In other viral systems, this RNA has been shown to modulate host cell transcription. Here, we report the presence of measles virus leader RNA in both cytoplasmic and nuclear fractions of infected HeLa cells as well as T- and B-lymphoid cells. A sharp and rapid increase in the concentration of leader RNA in the nucleus of infected HeLa cells was also observed. The presence and accumulation of leader RNA in the nucleus of infected cells supports the hypothesis that the leader RNA plays a role in the down regulation of host cell transcription and may be responsible for the suppression of immunoglobulin synthesis by measles virus-infected B cells. Such alterations in immune responsiveness could aid in the establishment of a persistent infection by measles virus.

Gene expression of nonsegmented negative strand RNA viruses

Nonsegmented negative strand RNA viruses comprise major human and animal pathogens in nature. This class of viruses is ubiquitous and infects vertebrates, invertebrates, and plants. Our laboratory has been working on the gene expression of two prototype nonsegmented negative strand RNA viruses, vesicular stomatitis virus (a rhabdovirus) and human parainfluenza virus 3 (a paramyxovirus). An RNA-dependent RNA polymerase (L and P protein) is packaged within the virion which faithfully copies the genome RNA in vitro and in vivo; this enzyme complex, in association with the nucleocapsid protein (N), is also involved in the replication process. In this review, we have presented up-to-date information of the structure and function of the RNA polymerases of these two viruses, the mechanisms of transcription and replication, and the role of host proteins in the life-cycle of the viruses. These detailed studies have led us to a better understanding of the roles of viral and cellular proteins in the viral gene expression.

Induction of a chicken small heat shock (stress) protein: evidence of multilevel posttranscriptional regulation

A novel form of regulation of expression of a vertebrate heat shock gene is described. A cDNA clone encoding human Hsp27 was shown to specifically recognize chicken Hsp23 RNA by Northern (RNA) blot analysis and hybrid-select translation. This probe was then used to measure chicken hsp23 gene activity in control and heat-stressed cells. The hsp23 gene(s) was transcriptionally active in non-heat-stressed cells, and its rate of transcription did not increase significantly upon heat shock. Cytoplasmic Hsp23 mRNA, which was metabolically very stable in nonstressed cells, underwent a fourfold increase in amount after a 1-h heat shock, resulting in a twofold increase in Hsp23 mRNA in polysomes. Hsp23 mRNA was relatively abundant and translationally active even in non-heat-shocked cells. Taken together, these data implicated posttranscriptional nuclear events as an important control point for induction of Hsp23 RNA transcripts. The protein half-life of Hsp23 increased from approximately 2 h in control cultures to 13 h in heat-shocked cells, revealing a second major control point. Hsp23 which was synthesized prior to heat shock also increased in stability and contributed to the overall accumulation of Hsp23 in heat-shocked cells. Cycloheximide had no effect on this change in Hsp23 half-life, while dactinomycin blocked the stabilization of Hsp23, suggesting a need for newly synthesized RNA. These data indicated that stabilization of Hsp23 protein and posttranscriptional nuclear events resulting in increased production of Hsp23 mRNA were primarily responsible for a 13-fold increase in the accumulation of newly synthesized Hsp23 after 1 h of heat shock. The regulation of the hsp23 gene is discussed in comparison with several other posttranscriptionally regulated genes, including the proto-oncogene c-fos, the developmentally regulated chicken delta-crystallin gene, and regulation of cellular gene expression by the proto-oncogene c-myc.

Induction of a chicken small heat shock (stress) protein: evidence of multilevel posttranscriptional regulation

A novel form of regulation of expression of a vertebrate heat shock gene is described. A cDNA clone encoding human Hsp27 was shown to specifically recognize chicken Hsp23 RNA by Northern (RNA) blot analysis and hybrid-select translation. This probe was then used to measure chicken hsp23 gene activity in control and heat-stressed cells. The hsp23 gene(s) was transcriptionally active in non-heat-stressed cells, and its rate of transcription did not increase significantly upon heat shock. Cytoplasmic Hsp23 mRNA, which was metabolically very stable in nonstressed cells, underwent a fourfold increase in amount after a 1-h heat shock, resulting in a twofold increase in Hsp23 mRNA in polysomes. Hsp23 mRNA was relatively abundant and translationally active even in non-heat-shocked cells. Taken together, these data implicated posttranscriptional nuclear events as an important control point for induction of Hsp23 RNA transcripts. The protein half-life of Hsp23 increased from approximately 2 h in control cultures to 13 h in heat-shocked cells, revealing a second major control point. Hsp23 which was synthesized prior to heat shock also increased in stability and contributed to the overall accumulation of Hsp23 in heat-shocked cells. Cycloheximide had no effect on this change in Hsp23 half-life, while dactinomycin blocked the stabilization of Hsp23, suggesting a need for newly synthesized RNA. These data indicated that stabilization of Hsp23 protein and posttranscriptional nuclear events resulting in increased production of Hsp23 mRNA were primarily responsible for a 13-fold increase in the accumulation of newly synthesized Hsp23 after 1 h of heat shock. The regulation of the hsp23 gene is discussed in comparison with several other posttranscriptionally regulated genes, including the proto-oncogene c-fos, the developmentally regulated chicken delta-crystallin gene, and regulation of cellular gene expression by the proto-oncogene c-myc.

Characterization of an in vitro system for the synthesis of mRNA from human parainfluenza virus type 3

A cell extract derived from human parainfluenza virus type 3-infected human lung carcinoma (HLC) cells synthesized mRNA in vitro. Under optimal conditions, the extract was able to support transcription of all virus-encoded genes as determined by hybridization analyses. The RNA products contained full-length poly(A)-containing mRNA species similar to those observed in acutely infected cells. Further purification of the viral nucleocapsids from the infected HLC cell extract resulted in total loss of the capacity of the extract to synthesize mRNA in vitro. However, the addition of cytoplasmic extracts from uninfected HLC cells to the nucleocapsid preparations restored transcription to levels observed in the infected cell lysates, indicating requirement of a host factor(s) in the human parainfluenza virus type 3 transcription process. In distinction to the abundant transcription observed in the cell extract from HLC cells, cell extract prepared from CV-1 cells failed to support transcription in vitro. High levels of RNase activity in the cell extract from CV-1 cells appears to be the principal reason for this difference.

Measles virus synthesizes both leaderless and leader-containing polyadenylated RNAs in vivo

The minus-sense RNA genome of measles virus serves as a template for synthesizing plus-sense RNAs of genomic length (antigenomes) and subgenomic length [poly(A)+ RNAs]. To elucidate how these different species are produced in vivo, RNA synthesized from the 3'-proximal N gene was characterized by Northern RNA blot and RNase protection analyses. The results showed that measles virus produced three size classes of plus-sense N-containing RNA species corresponding to monocistronic N RNA, bicistronic NP RNA, and antigenomes. Unlike vesicular stomatitis virus, measles virus does not produce a detectable free plus-sense leader RNA. Instead, although antigenomes invariably contain a leader sequence, monocistronic and bicistronic poly(A)+ N-containing RNAs are synthesized either without or with a leader sequence. We cloned and characterized a full-length cDNA representing a product of the latter type of synthesis. mRNAs and antigenomes appeared sequentially and in parallel with leaderless and leader-containing RNAs. These various RNA species accumulated concurrently throughout infection. However, cycloheximide preferentially inhibited accumulation of antigenomes and leader-containing RNA but not leaderless and subgenomic RNAs late in infection, suggesting that synthesis of the former RNA species requires a late protein function or a continuous supply of structural proteins or both. These results reveal a previously undescribed mechanism for RNA synthesis in measles virus.

Nucleotide sequence analysis of the L gene of Newcastle disease virus: homologies with Sendai and vesicular stomatitis viruses

The nucleotide sequence of the L gene of the Beaudette C strain of Newcastle disease virus (NDV) has been determined. The L gene is 6704 nucleotides long and encodes a protein of 2204 amino acids with a calculated molecular weight of 248822. Mung bean nuclease mapping of the 5' terminus of the L gene mRNA indicates that the transcription of the L gene is initiated 11 nucleotides upstream of the translational start site. Comparison with the amino acid sequences of the L genes of Sendai virus and vesicular stomatitis virus (VSV) suggests that there are several regions of homology between the sequences. These data provide further evidence for an evolutionary relationship between the Paramyxoviridae and the Rhabdoviridae. A non-coding sequence of 46 nucleotides downstream of the presumed polyadenylation site of the L gene may be part of a negative strand leader RNA.

Detection of polycistronic transcripts in Newcastle disease virus infected cells and identification of their sequence content

The synthesis of six to seven polycistronic transcripts of Newcastle disease virus (NDV) in BHK cells was detected by Northern hybridization using cDNA clones generated by reverse transcription of five NDV mRNAs. Within the molecular weight range resolved by the gel electrophoresis system employed, four of the transcripts were suggested to be distronic, containing sequences of two genes, NP-P, P-M, M-F0 and F0-HN, respectively. In addition, tricistronic molecules of M-F0-HN and possibly of NP-P-M as well as P-M-F0 appeared to develop, although they were very low in amount. These data suggest a gene order of NP-P-M-F0-HN on the NDV genome. The polycistronic as well as monocistronic transcripts were generated with an almost constant proportion in amount throughout the virus replication. Further, at least several of them were also generated under the conditions where only the primary transcription was allowed by inhibiting de novo protein synthesis. Therefore, it appears likely that there is no distinct temporal control in NDV genome expression.

Human parainfluenza virus type 3: messenger RNAs, polypeptide coding assignments, intergenic sequences, and genetic map

cDNA clones of mRNAs for the major nucleocapsid protein (NP), the nucleocapsid P protein plus the nonstructural C protein (P+C), and the matrix protein (M) of human parainfluenza virus type 3 (PF3) were identified by hybrid arrest and hybrid selection of in vitro translation. Previously, cDNA clones were identified and sequenced for the hemagglutinin-neuraminidase glycoprotein (HN) and the fusion glycoprotein (F) mRNAs (N. Elango, J. E. Coligan, R. C. Jambou, and S. Venkatesan, J. Virol. 57:481-489, 1986; M. K. Spriggs, R. A. Olmsted, S. Venkatesan, J. E. Coligan, and P. L. Collins, Virology 152:241-251, 1986). Synthetic oligonucleotides, designed from nucleotide sequences of the cDNAs, were used to direct dideoxynucleotide sequencing of gene junctions in PF3 genomic RNA (vRNA). From sequencing of vRNA, a sixth viral gene was detected and identified as the large nucleocapsid protein (L) gene by hybridization of a synthetic oligonucleotide to intracellular PF3 mRNAs separated by gel electrophoresis. The order of the six PF3 genes on vRNA was 3'-NP-P+C-M-F-HN-L-5'. The five intergenic regions consisted of the trinucleotide 3'-GAA. The PF3 genes initiated with semiconserved 10-nucleotide gene-start sequences and terminated with semiconserved 12-nucleotide gene-end sequences. The M gene terminated with an aberrant gene-end sequence; analysis of intracellular mRNA showed that this aberrant sequence correlated with a disproportionately high accumulation of readthrough mRNA. These studies showed that PF3 encodes six unique mRNAs (NP, P+C, M, F, HN, and L) that encode seven proteins (NP, P, C, M, F, HN, and L) and provided evidence of a close relationship between PF3 and Sendai (murine parainfluenza type 1) viruses.

Conserved structures among the nucleocapsid proteins of the paramyxoviridae: complete nucleotide sequence of human parainfluenza virus type 3 NP mRNA

The nucleotide sequence of the mRNA coding for the nucleocapsid protein (NP) of the paramyxovirus, human parainfluenza virus type 3 (PIV-3), has been determined. The NP mRNA was found to contain 1642 bases, excluding poly(A), and encode a protein of 515 amino acids, with a molecular weight of 57,823. Amino acid residues 1 through 420 of PIV-3 NP protein showed extensive sequence homology with the corresponding amino acids of Sendai virus nucleocapsid protein. There was virtually no homology between the last 95 amino acids. Comparison of the NP proteins of PIV-3, Sendai virus, measles virus, and canine distemper virus revealed, from amino acid residues 160 through 390, some conserved areas between the corresponding proteins of these paramyxoviruses. The 5' terminal sequence of PIV-3 NP mRNA (5'-AGGATTAAAG-3') was similar to the conserved sequence (formula; see text) found at the 5' termini of Sendai virus mRNAs. Both PIV-3 NP and Sendai virus mRNAs had a common 3' terminal tetranucleotide (5'-TAAG-3') preceding the poly (A) tail.

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.

Cloning and gene assignment of mRNAs of human parainfluenza virus 3

Cytoplasmic poly(A)-containing RNA from parainfluenza virus 3-infected cells was used as template to construct a cDNA library that was cloned into the EcoRV site of the plasmid pMG5. The resulting clones were screened with [32P]-labeled cDNA probes made from infected and mock-infected cell mRNAs. The virus specificity of the clones was confirmed by Northern blot hybridization. The viral clones were grouped into five different families by hybridization with individual size-selected reverse transcripts representing the major classes of poly(A)+-RNA from virus-infected cells. The five groups were shown to be unrelated on the basis of cross-colony hybridization and corresponded to five unique classes of intracellular viral poly(A)+-RNAs. Clones representing the NP and P genes of PIV-3 were identified by both hybrid-selected and hybrid-arrested translation. Clones specific for the P gene selected mRNA that directed the synthesis of P protein and another polypeptide of 21 kDa. This additional polypeptide comigrated with protein VP8 previously identified in virions and in infected cell lysates.

Proteins associated with human parainfluenza virus type 3

The polypeptides associated with human parainfluenza virus type 3 were identified. Five proteins were present in detergent- and salt-resistant viral cores. Of these, three proteins designated NP0, NP1, and NP2 of 68,000, 58,000, and 52,000 daltons, respectively, were stably associated with 50S RNA in CsCl gradient-purified nucleocapsids. The amounts of NP1 and NP2 were variable, and these proteins were shown to be structurally related to the major nucleocapsid protein (NP0) by partial Staphylococcus aureus V8 protease mapping. The other core proteins included a 240K protein designated L (candidate for the viral polymerase) and an 84K protein designated as the phosphoprotein (P) on the basis of a predominant incorporation of Pi. The viral envelope had four prominent proteins (72, 53, 40, and 12K) under reducing conditions of electrophoresis. The 72 and 53K proteins were specifically labeled with [3H]glucosamine and [3H]mannose. When sulfhydryl reagents were removed, a new 62K protein was visualized in place of the 72, 53, and 12K proteins. The 53 and 12K proteins were interpreted to be the two subunits (F1 and F2) of the fusion protein, and the 72K protein was designated as the HN (hemagglutinin-neuraminidase) glycoprotein. The unglycosylated 40K protein represented the viral matrix protein (M). Immunoprecipitation of infected cell lysates with rabbit hyperimmune antiserum against purified virus confirmed the viral origin of these polypeptides.

Identification and predicted sequence of a previously unrecognized small hydrophobic protein, SH, of the paramyxovirus simian virus 5

A previously unrecognized gene (SH) has been identified on the virion RNA of the paramyxovirus simian virus 5 between the genes for the fusion protein and the hemagglutinin-neuraminidase. An SH mRNA of 292 nucleotides (plus polyadenylate residues), transcribed from the SH gene, has been identified. The SH mRNA contains a single open reading frame which encodes a polypeptide of 44 amino acids with a molecular weight of 5,012. The SH polypeptide is predicted to contain an extensive hydrophobic region. This protein has been identified in simian virus 5-infected cells, and it has been shown to be encoded by the SH mRNA by in vitro translation of size-fractionated mRNAs, hybrid-arrest translation, and hybrid-selection translation.

RNA sequence and transcriptional properties of the 3' end of the Newcastle disease virus genome

The 3' end of the genomic RNA of Newcastle disease virus (NDV) has been sequenced and the leader RNA defined. Using hybridization to a 3'-end-labeled genome, leader RNA species from in vitro transcription reactions and from infected cell extracts were found to be 47 and 53 nucleotides long. In addition, the start site of the 3'-proximal mRNA was determined by sequence analysis of in vitro [beta-82P]GTP-labeled transcription products. The genomic sequence extending beyond the leader region demonstrated an open reading frame for at least 42 amino acids and probably represents the amino terminus of the nucleocapsid protein (NP). The terminal 8 nucleotides of the NDV genome were identical to those of measles virus and Sendai virus while the sequence of the distal half of the leader region was more similar to that of vesicular stomatitis virus. These data argue for strong evolutionary relatedness between the paramyxovirus and rhabdovirus groups.

Nucleotide sequences of the 1B and 1C nonstructural protein mRNAs of human respiratory syncytial virus

The genes encoding the 1C and 1B mRNAs of human respiratory syncytial (RS) virus are first in the order of viral transcription and encode nonstructural (NS) proteins of approximate molecular weights 14,000 and 11,000, respectively, estimated by gel electrophoresis. The complete nucleotide sequences of the 1C and 1B mRNAs determined from several full-length cDNA clones are described. The 1C and 1B mRNAs contain 528 and 499 nucleotides, respectively, exclusive of poly(A), and encode proteins of 139 and 124 amino acids. The calculated molecular weights of the predicted NS1C and NS1B proteins are 15,567 and 14,674, respectively. Both mRNA sequences contain the 5'-terminal sequence, 5' GGGGCAAAU . . . , and the 3'-terminal sequence, 5' . . . AGUAUA(N)1-4-poly(A), that were identified previously as conserved among six other RS viral mRNAs. In addition, a dicistronic readthrough RNA having the general structure 5' 1C mRNA-intergenic sequence-1B mRNA 3' was identified by dideoxynucleotide sequencing of intracellular poly(A)+ RNA using a DNA primer derived from a 1B-cDNA clone. In the dicistronic RNA, the nucleotide sequences of the 1C and 1B cistrons are separated by, in mRNA sense, four A residues and the intergenic sequence 5' . . . CUUAACAGAAGACAAAAAN . . . 3' (N represents unidentified nucleotide). The significance of these sequences is discussed.

The envelope-associated 22K protein of human respiratory syncytial virus: nucleotide sequence of the mRNA and a related polytranscript

We recently determined that respiratory syncytial virus (strain A2) encodes a fourth unique envelope-associated virion protein that has molecular weight of approximately 24,000, as estimated by gel electrophoresis. The nucleotide sequence of the mRNA encoding this novel protein has now been determined from five cDNA clones, including three that contain the complete mRNA sequence. The complete mRNA sequence is 957 nucleotides, exclusive of polyadenylate, and contains two partially overlapping open reading frames. The 5'-proximal open reading frame is favored for utilization by the criteria of the location and sequence of its translational start site. Furthermore, the calculated molecular weight of the encoded protein, 22,153, is in agreement with the previous estimate of 24,000 for the authentic protein identified by hybrid selection and in vitro translation. The sequence of the predicted protein, now designated the 22K protein, contains 194 amino acids, is relatively hydrophilic, and appears to be the most basic of the respiratory syncytial virus proteins. The mRNA also contains a second, internal open reading frame which would encode a protein of 90 amino acids. However, no evidence for this translation product is known. The first nine nucleotides in the mRNA sequence, 5'-GGGGCAAAU, are identical to the conserved sequence identified previously at the 5' termini of seven other respiratory syncytial viral mRNAs; the sequence at the 3' end of the 22K mRNA, 5'. . . AGUUAUUU-polyadenylate, contains the elements of the previously identified 3'-terminal consensus sequence for respiratory syncytial virus mRNAs, AGUUAA(N)1-4-polyadenylate (P. L. Collins, Y. T. Huang, and G. W. Wertz, Proc. Natl. Acad. Sci. U.S.A. 81:7683-7687). In addition, we present and describe the intergenic sequence of a dicistronic RNA derived from readthrough of the F and 22K protein genes.

The 1A protein gene of human respiratory syncytial virus: nucleotide sequence of the mRNA and a related polycistronic transcript

The 1A mRNA is the smallest mRNA of human respiratory syncytial (RS) virus and encodes a single protein of approximate molecular weight 9500 as estimated previously by gel electrophoresis. The nucleotide sequence of the 1A mRNA, determined from several full-length cDNA clones, is reported. The 1A mRNA consists of 405 nucleotides, exclusive of poly(A), with relatively long nontranslated regions at the 5' and 3' ends (84 and 126 nucleotides, respectively). The sequences at the 5' and 3' termini of the 1A mRNA conform to the previously described conserved consensus sequences for RS virus mRNAs. The major open reading frame of the 1A mRNA codes for a hydrophobic polypeptide of 64 amino acids with a calculated molecular weight of 7536. The 5' terminus of the 1A mRNA was mapped and sequenced by primer extension under conditions for sequencing by partial chain termination. These experiments also identified a population of polycistronic RNA having the general structure: 5' M protein mRNA-1A mRNA 3'. This polytranscript was sequenced in order to determine the intergenic sequence. In the polytranscript, the nucleotide sequence of the M gene is followed by, in mRNA sense, six A residues and the intergenic sequence 5' ... UAUACACNN (N represents unidentified nucleotide).

Analysis and gene assignment of mRNAs of a paramyxovirus, simian virus 5

Polypeptides synthesized by the paramyxovirus SV5 in infected CV-1 cells were readily identified when the host cell was treated with actinomycin D. The unglycosylated forms of HN and Fo synthesized in infected cells in the presence of tunicamycin and HN and Fo synthesized in vitro were identified by immunoprecipitation with specific antibodies. Separation of SV5-specific poly(A)-containing RNAs on methyl-mercury agarose gels and in vitro translation of fractions, indicated that the viral polypeptides were translated from individual mRNAs except P (Mr approximately 44K) and the nonstructural polypeptide V (Mr approximately 24K) for which the mRNAs could not be separated. cDNA copies of SV5-specific mRNAs were synthesized and cloned in plasmid pBR322. Clones to NP, P + V, M, F, and HN were identified by hybrid-arrest and hybrid-selection translation of SV5 mRNAs. Tryptic peptide mapping of polypeptides P and V indicated that the peptides of V were a subset of those of P. Hybridization of cDNA probes to infected cell mRNAs separated on agarose gels permitted identification of the NP, P + V, M, F, and HN mRNAs and presumptive polycistronic mRNAs. The sizes and sequence homologies of these polycistronic mRNAs were used to derive a likely gene order on the SV5 50 S genome RNA.

Stress mRNA metabolism in canavanine-treated chicken embryo cells

Four major chicken stress mRNAs with apparent molecular weights of 1.2 X 10(6), 0.88 X 10(6), 0.59 X 10(6), and 0.25 X 10(6) to 0.28 X 10(6) were separated on acidic agarose-urea gels. Using cell-free translation, the coding assignments of these mRNAs were determined to be stress proteins with apparent molecular weights of 88,000, 71,000, 35,000, and 23,000. Despite high levels of translational activity in vivo and in vitro, no newly synthesized mRNA for the 23-kilodalton stress protein was detected on gels under conditions which readily allowed detection of other stress mRNAs, suggesting activation of a stored or incompletely processed mRNA. Cloned Drosophila heat shock genes were used to identify and measure changes in cellular levels of the two largest stress mRNAs. Synthesis of these mRNAs increased rapidly during the first hour of canavanine treatment and continued at a high rate for at least 7 h, with the mRNAs attaining new steady-state levels by ca. 3 h. Both of these inducible stress mRNAs had very short half-lives compared with other animal cell mRNAs. Using an approach-to-steady-state analysis, the half-lives were calculated to be 89 min for the mRNA encoding the 88-kilodalton stress protein and 46 min for the mRNA encoding the 71-kilodalton stress protein. Chicken 18S and 28S rRNA synthesis was inhibited, and actin mRNA levels measured with cloned cDNA encoding chicken beta-actin slowly declined in canavanine-treated cells.

Transcriptional mapping of human respiratory syncytial virus

A transcriptional map for human respiratory syncytial virus was determined by measuring the kinetics of viral gene inactivation in response to UV irradiation. Monolayer cell cultures of respiratory syncytial virus-infected HEp-2 cells were exposed to UV light, and residual viral RNA synthesis was monitored both by gel electrophoresis and by hybridization to dot blots of cloned cDNAs of the 10 known viral genes. Target sizes for the 10 individual viral genes were calculated relative to the UV sensitivity of intracellular viral genome replication. Target size analysis indicated that the 10 viral genes were transcribed as a single transcriptional unit and that the transcription of an individual gene was dependent on the prior transcription of all the preceding genes. The order of gene transcription (with nomenclature according to encoded proteins) was determined to proceed from the promoter as follows: 14K, 11K, N, P, M, 9.5K, 36K, F, 24K, L.

Stress mRNA metabolism in canavanine-treated chicken embryo cells

Four major chicken stress mRNAs with apparent molecular weights of 1.2 X 10(6), 0.88 X 10(6), 0.59 X 10(6), and 0.25 X 10(6) to 0.28 X 10(6) were separated on acidic agarose-urea gels. Using cell-free translation, the coding assignments of these mRNAs were determined to be stress proteins with apparent molecular weights of 88,000, 71,000, 35,000, and 23,000. Despite high levels of translational activity in vivo and in vitro, no newly synthesized mRNA for the 23-kilodalton stress protein was detected on gels under conditions which readily allowed detection of other stress mRNAs, suggesting activation of a stored or incompletely processed mRNA. Cloned Drosophila heat shock genes were used to identify and measure changes in cellular levels of the two largest stress mRNAs. Synthesis of these mRNAs increased rapidly during the first hour of canavanine treatment and continued at a high rate for at least 7 h, with the mRNAs attaining new steady-state levels by ca. 3 h. Both of these inducible stress mRNAs had very short half-lives compared with other animal cell mRNAs. Using an approach-to-steady-state analysis, the half-lives were calculated to be 89 min for the mRNA encoding the 88-kilodalton stress protein and 46 min for the mRNA encoding the 71-kilodalton stress protein. Chicken 18S and 28S rRNA synthesis was inhibited, and actin mRNA levels measured with cloned cDNA encoding chicken beta-actin slowly declined in canavanine-treated cells.

Identification of a tenth mRNA of respiratory syncytial virus and assignment of polypeptides to the 10 viral genes

Nine mRNAs, their cDNA clones, and a genome transcriptional map have been reported previously for respiratory syncytial virus (P. L. Collins and G. W. Wertz, Proc. Natl. Acad. Sci. U.S.A. 80:3208-3212, 1983). We report here the identification of a 10th viral mRNA, designated mRNA 2b (molecular weight [MW] ca. 0.39 X 10(6)), that was detected by RNA (Northern) blot hybridization with cDNA clones. Analysis of a polycistronic readthrough transcript was used to deduce the position in the viral transcriptional map of the gene encoding the newly identified mRNA. The polypeptide coding assignments of 9 of the 10 respiratory syncytial virus mRNAs were determined. Individual viral mRNAs were purified by hybridization selection with nine unique, nonoverlapping cDNA clones and analyzed by translation in vitro. Each of the nine mRNAs encoded a single polypeptide chain. The coding assignments were as follows: RNA 1a (MW ca. 0.24 X 10(6)), a 9,500-dalton (9.5K) protein; RNA 1b (MW 0.26 X 10(6)), an 11K protein; RNA 1c (MW 0.26 X 10(6)), a 14K protein; RNA 2a (MW 0.38 X 10(6)), the 34K phosphorylated (P) protein; RNA 2b (MW 0.39 X 10(6)), a 36K protein; RNA 3a (MW 0.40 X 10(6)), the 26K matrix (M) protein; RNA 3b (MW 0.40 X 10(6)), a 24K protein; RNA 4 (MW 0.47 X 10(6)), the 42K major nucleocapsid (N) protein; and RNA 5 (MW 0.74 X 10(6)), a 59K protein. The cDNA clones used for the hybridization selections were respiratory syncytial virus specific and did not hybridize with uninfected-cell mRNA; therefore the proteins synthesized with the selected mRNAs were virus specific. The 9.5K, 11K, 14K, 24K, M, P, 36K, N, and 59K proteins were encoded by different mRNAs; therefore these nine proteins are all unique. The 9.5K, 11K, 14K, 24K, M, P, and N proteins synthesized in vitro with hybrid-selected mRNAs each had counterparts with the same electrophoretic mobilities in extracts of virus-infected cells. The in vitro polypeptides and their authentic counterparts were shown to be closely related by limited digest peptide mapping. The 36K and 59K polypeptides lacked counterparts with the same electrophoretic mobilities in infected cells and therefore are candidates for the unprocessed precursors of the viral F and G glycoproteins. The 10th viral mRNA, the 2,500K RNA 7, was not tested directly but is the only known mRNA of the appropriate size to encode the 200K large (L) protein of the viral nucleocapsid. These assignments account for all 10 of the reported viral mRNAs and bring to 10 the number of known unique viral proteins.

Isolation and characterization of measles virus intracellular nucleocapsid RNA

Protocols have been established for the preparation of large amounts of pure measles virus intracellular nucleocapsids. As a result, it has been possible to routinely achieve nucleocapsid RNA yields of approximately 200 micrograms (from approximately 5 X 10(8) infected cells). Electrophoretic analysis of this RNA under denaturing conditions revealed a single species whose mass was estimated at approximately 4.8 X 10(6) daltons. Electron microscopic assessment of nucleocapsid RNA contour lengths corroborated the electrophoretic size determination. Total nucleocapsid RNA was shown to contain both negative- and positive-stranded species distributed in a ratio of 2 to 3 genome polarity molecules for each antigenome RNA. Hybridization studies established that all of the virus-specified polyadenylated RNAs were encoded by the negative-stranded nucleocapsid RNA and, therefore, that this nucleocapsid RNA was the measles genome. Examination of the measles virus-specified, polyadenylated transcription products by HCHO-agarose gel electrophoresis revealed at least nine distinct RNA species (rather than the six predicted measles mRNAs). The significance of these observations is discussed.

Amino acid sequence of human respiratory syncytial virus nucleocapsid protein

Amino acid sequence of the human respiratory syncytial (RS) virus nucleocapsid (NC) protein, deduced from the DNA sequence of a recombinant plasmid, is presented. The cDNA plasmid (pRSB11) has 1412 bp of RS viral NC sequence and lacks six nucleotides of the 5' end of mRNA. There is a single long open reading frame encoding 467 amino acids. This 51540 dal protein is rich in basic amino acids and has no homologies with other known viral capsid proteins.

Molecular cloning of the 3'-proximal third of Sendai virus genome

Portions of the Sendai virus genome were randomly cloned by using virion 50S RNA and calf thymus DNA pentanucleotides as primers. The recombinant clones were probed first with radiolabeled products of an in vitro virion RNA polymerase reaction to locate early message clones and then with a probe from the viral genome 3' end to locate the most 3'-proximal clones. Clones were then ordered from the 3' end of the genome and used to construct a genetic map of the 3'-proximal third of the genome by hybrid-selection of mRNAs. We report that the gene order for this region is 3'-NP - P + C - M-5' and that the genetic loci of the viral P and C proteins cannot be separated by these techniques.

cDNA cloning and transcriptional mapping of nine polyadenylylated RNAs encoded by the genome of human respiratory syncytial virus

We have isolated cDNA clones representing nine unique poly(A)+ RNAs transcribed from the genome of human respiratory syncytial virus, a paramyxovirus. A cDNA library was constructed by using poly(A)+ RNA from virus-infected cells as template and the Escherichia coli plasmid pBR322 as vector. Viral cDNA clones were identified by hybridization with cDNA probes prepared from viral genomic RNA. The viral clones were grouped into nine different families by hybridization with individual size-selected reverse transcripts representing the major classes of poly(A)+ RNA from virus-infected cells. The largest clone from each family was selected for analysis. These nine clones, molecular sizes ranging from 520 to 2,600 base pairs, were shown to be unrelated on the basis of reciprocal hybridization using dot-blots. These cDNA clones were then used as hybridization probes to analyze intracellular viral RNAs that had been separated by gel electrophoresis and transferred to diazobenzyloxymethyl-paper. All nine clones hybridized with intracellular viral genomic RNA, confirmation of virus specificity. Nine unique intracellular viral poly(A)+ RNAs were identified [molecular sizes ranging from 720 to 7,500 nucleotides, including poly(A)]. Comparison of the sizes of these major RNAs and the cDNA clones indicated that a number of the clones represented nearly complete copies of the corresponding RNAs. Several other intracellular viral poly(A)+ RNAs appeared to be polycistronic by the criteria of molecular weights and homologies to various combinations of cDNA clones. The sizes and sequence contents of these polycistronic RNAs were used to prepare a transcriptional map whose significance is discussed.

Simian virus 40 and polyoma virus induce synthesis of heat shock proteins in permissive cells

During the lytic infection of monkey and mouse cells with simian virus 40 and polyoma virus, respectively, the preferentially increased synthesis of two host proteins of 92,000 and 72,000 Mr was observed by 15 to 20 h after infection besides the general stimulation of most cellular proteins. The incubation of uninfected monkey and mouse cell cultures for 30 to 60 min at 43.5 degrees C induced the enhanced synthesis of at least three proteins of 92,000, 72,000 and 70,000 Mr, the last one being the major heat shock protein of mammalian cells. Two-dimensional gel electrophoresis and partial proteolytic digestion confirmed that the same 92,000- and 72,000-Mr proteins are stimulated by virus infection and thermal treatment. In simian virus 40-infected CV-1 cells, we also observed the weak stimulation of a 70,000-Mr protein comigrating in gel electrophoresis with the major heat shock protein. The 92,000-, 72,000- and 70,000-Mr proteins of monkey cells are structurally very similar to the corresponding proteins of mouse cells. In immunoprecipitations, no specific association of these proteins to simian virus 40 T antigens was noticed.

Construction and characterization of cDNA clones for four respiratory syncytial viral genes

Cytoplasmic poly(A)-containing RNA from respiratory syncytial virus-infected cells was used as a template to synthesize oligo(dT)-primed cDNAs. Discrete size classes of single-stranded cDNAs, resolved by alkali agarose gel electrophoresis, were used separately to construct double-stranded cDNAs that were subsequently inserted into the plasmid vector pBR322 at the Pst I site by means of oligo(dG)oligo(dC) tailing. After transfection of Escherichia coli, recombinant plasmids were screened mostly by serial rounds of hybrid selection of mRNAs from virus-infected cells and subsequent in vitro translation of the selected mRNAs. Comparative peptide mapping of the translation products with those of authentic virion proteins served to establish the viral origin of the cDNA recombinants. In this manner, four distinct classes of recombinant plasmids were identified. These encode sequences corresponding to those of respiratory syncytial virus nucleocapsid protein, matrix protein, phosphoprotein, and a nonstructural protein.

Simian virus 40 and polyoma virus induce synthesis of heat shock proteins in permissive cells

During the lytic infection of monkey and mouse cells with simian virus 40 and polyoma virus, respectively, the preferentially increased synthesis of two host proteins of 92,000 and 72,000 Mr was observed by 15 to 20 h after infection besides the general stimulation of most cellular proteins. The incubation of uninfected monkey and mouse cell cultures for 30 to 60 min at 43.5 degrees C induced the enhanced synthesis of at least three proteins of 92,000, 72,000 and 70,000 Mr, the last one being the major heat shock protein of mammalian cells. Two-dimensional gel electrophoresis and partial proteolytic digestion confirmed that the same 92,000- and 72,000-Mr proteins are stimulated by virus infection and thermal treatment. In simian virus 40-infected CV-1 cells, we also observed the weak stimulation of a 70,000-Mr protein comigrating in gel electrophoresis with the major heat shock protein. The 92,000-, 72,000- and 70,000-Mr proteins of monkey cells are structurally very similar to the corresponding proteins of mouse cells. In immunoprecipitations, no specific association of these proteins to simian virus 40 T antigens was noticed.

Newcastle disease virus stimulates the cellular accumulation of stress (heat shock) mRNAs and proteins

A biological agent, Newcastle disease virus, stimulated the synthesis of stress proteins in cultured chicken embryo cells. Previously, only physical and chemical agents were known to induce these proteins. The levels of translatable stress mRNAs were elevated in cells infected with avirulent or virulent strains; however, stress protein synthesis was stimulated strongly only in cells infected by avirulent strains. As did several other paramyxoviruses, avirulent strains of Newcastle disease virus stimulated the synthesis of glucose-regulated proteins as well as stress proteins. Possible stimuli of the synthesis of these two sets of proteins in paramyxovirus-infected cells are considered.

Coding assignments of the five smaller mRNAs of Newcastle disease virus

The polypeptide coding assignments for the five messengers of the 18S size class of Newcastle disease virus (NDV) RNA have been determined by cell-free translation of individual RNAs separated by gel electrophoresis. Listed in order of their decreasing electrophoretic mobilities in acid agarose-urea gels, the coding assignments of the RNAs were as follows: RNA 1, M protein; RNA 2, P protein; RNA 3, NP; RNA 4, F glycoprotein; and RNA 5, HN glycoprotein. RNA 2 also directed the synthesis of 33- and 36-kilodalton proteins, which were tentatively identified as being overlapping segments of the P protein. The 33- and 36-kilodalton polypeptides could be detected in infected cells, but not in purified virions of NDV. Since the other unique NDV RNA, a 35S species, has been shown previously to encode the viral L protein, these results complete the coding assignments of the six known NDV mRNAs.

Fatty acid modification of Newcastle disease virus glycoproteins

The fatty acid acylation of Newcastle disease virus hemagglutininin-neuraminidase and fusion glycoproteins was assayed. [3H]palmitate label was associated with cytoplasmic fusion proteins (F0 and F1) and virion-associated F1. In contrast, there was no detectable [3H]palmitate label associated with the hemagglutin-neuraminidase protein in Newcastle disease virus-infected Chinese hamster ovary cells or chicken embryo cells or in virions released from these cells. Thus, fatty acid modification may not be important for the maturation of some glycoproteins.