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PubMed2002

The carboxyl segment of the mumps virus V protein associates with Stat proteins in vitro via a tryptophan-rich motif.

Viruses of the Paramyxovirinae, similar to other viruses, have evolved specific proteins that interdict IFN action as part of a general strategy to counteract host innate immunity. In many (but not all) cases, this interdiction is accompanied by a lowering of the intracellular levels of the STAT proteins. Among rubulaviruses, there is a notable variation in how they interfere with IFN action. Whereas SV41, SV5, and MuV all act by lowering Stat1, hPIV2 acts by lowering Stat2. Here, we show that the mumps and hPIV2 V proteins both form a complex with several Stat proteins in a mixed-extract assay. This suggests that the specific degradation of these Stat proteins is not determined by complex formation, but presumably at some later stage of the degradation pathway. V/Stat complex formation requires a specific carboxyl segment of V. However, a previously unrecognized trp-rich motif, rather than the Zn(++)-binding cys-cluster of this segment, appears to be required for V/Stat interaction. The C protein of Sendai (respiro-) virus, another P gene encoded protein, also forms a complex with Stat1, and prebinding of MuV V to Stat1 prevents the subsequent binding of SeV C. Our results suggest that rubulavirus V proteins may be related to both the C and the V proteins of respiroviruses.

Animals↗
PubMed2004

RNA synthesis during infection by Hendra virus: an examination by quantitative real-time PCR of RNA accumulation, the effect of ribavirin and the attenuation of transcription.

Hendra virus is one of two virus species within the newly-formed genus Henipavirus, subfamily Paramxyovirinae. It is a designated select agent with potential biosecurity threat to both human and animal health. Quantitative real-time PCR was used to measure viral RNA synthesis in Vero cells infected by Hendra virus, and to examine the inhibitory effect of ribavirin. It was also used to determine the points of attenuation during transcription of the six viral genes N, P, M, F, G and L by targeting amplicons located towards the 3' end of each gene. Major increases in viral RNA and virus yield occurred between 4 to 8 h and 8 to 10 h post infection, respectively. The effect of ribavirin was examined at a range of concentrations up to 400 microm. At 50 microm, RNA synthesis was reduced 9 fold, and virus yield 58 fold. As expected for a member of the order Mononegavirales, a gradient of transcription was observed in Hendra virus-infected cells. There was significant attenuation at the M-F and G-L junctions, more closely resembling Sendai virus (genus Respirovirus) than measles virus (genus Morbillivirus).

Animals↗
PubMed2006

Role of sialic acid-containing molecules in paramyxovirus entry into the host cell: a minireview.

Sialic acid-containing compounds play a key role in the initial steps of the paramyxovirus life cycle. As enveloped viruses, their entry into the host cell consists of two main events: binding to the host cell and membrane fusion. Virus adsorption occurs at the surface of the host cell with the recognition of specific receptor molecules located at the cell membrane by specific viral attachment proteins. The viral attachment protein present in some paramyxoviruses (Respirovirus, Rubulavirus and Avulavirus) is the HN glycoprotein, which binds to cellular sialic acid-containing molecules and exhibits sialidase and fusion promotion activities. Gangliosides of the gangliotetraose series bearing the sialic acid N-acetylneuraminic (Neu5Ac) on the terminal galactose attached in alpha2-3 linkage, such as GD1a, GT1b, and GQ1b, and neolacto-series gangliosides are the major receptors for Sendai virus. Much less is known about the receptors for other paramyxoviruses than for Sendai virus. Human parainfluenza viruses 1 and 3 preferentially recognize oligosaccharides containing N-acetyllactosaminoglycan branches with terminal Neu5Acalpha2-3Gal. In the case of Newcastle disease virus, has been reported the absence of a specific pattern of the gangliosides that interact with the virus. Additionally, several works have described the use of sialylated glycoproteins as paramyxovirus receptors. Accordingly, the design of specific sialic acid analogs to inhibit the sialidase and/or receptor binding activity of viral attachment proteins is an important antiviral strategy. In spite of all these data, the exact nature of paramyxovirus receptors, apart from their sialylated nature, and the mechanism(s) of viral attachment to the cell surface are poorly understood.

Antiviral Agents↗
PubMed2004

The L polymerase protein of parainfluenza virus 3 forms an oligomer and can interact with the heterologous Sendai virus L, P and C proteins.

We recently showed that the L protein of Sendai virus is present as an oligomer in the active P-L polymerase complex [Smallwood et al., Virology 304 (2002) 235]. We now demonstrate using two different epitope tags that the L protein of a second respirovirus, human parainfluenza type 3 virus (PIV3), also forms an L-L complex. L oligomerization requires the coexpression of the differentially epitope tagged L proteins. By exploiting a series of C-terminal truncations the L-L binding site maps to the N-terminal half of L. There is some complex formation between the heterologous PIV3 and Sendai L and P proteins; however, the heterologous L protein does not function in transcription of either the PIV3 or Sendai template. The PIV3 C protein binds PIV3 L and inhibits RNA synthesis in vitro and in vivo. Significant homology exists between the C proteins of PIV3 and Sendai and complex formation occurs between the PIV3 and Sendai heterologous C and L proteins. In addition, the heterologous C proteins can inhibit transcription at approximately 50% of the level of the homologous protein. These data suggest that while the C proteins may be functionally somewhat interchangeable, the L and P proteins are specific for each virus.

Animals↗
PubMed2005

Mapping of the RNA promoter of Newcastle disease virus.

The RNA promoters of the genome and antigenome of Newcastle disease virus (NDV) were studied by mutational analysis of their 3' terminal ends. Similarly to other paramyxoviruses, NDV RNA replication follows the rule of six, and the genomic and antigenomic promoters require two discontinuous regions: conserved region I (first 18 nucleotides) and conserved region II (nucleotides 73-90). Proper spacing between those regions and the phase of six in region II is critical for efficient RNA promoter activity. As expected, the gene start signal at the 3' end of the NDV genome was required for mRNA transcription, but not for RNA replication. Surprisingly, mutation of the polyadenylation signal in the 5' end did not affect gene expression transcription. Although the conserved region I of NDV (avulavirus) promoter appears to be more similar to that of Sendai virus (SeV) (respirovirus), conserved region II is analogous to that of rubulaviruses.

Cell Line↗
PubMed2000

The cleavage activation and sites of glycosylation in the fusion protein of Hendra virus.

Hendra virus (HeV) is an unclassified member of the Paramyxoviridae family that causes systemic infections in humans, horses, cats, guinea pigs and flying foxes. The fusion protein (F(0)) of members of the Paramyxoviridae family that cause systemic infections in vivo contains a basic amino acid-rich region at which the protein is activated by cleavage into two subunits (F(1) and F(2)). HeV F(0) lacks such a domain. We have determined the cleavage site in HeV F(0) by sequencing the amino terminus of the F(1) subunit and in view of the potential effect of glycosylation on the cleavage process have ascertained the sites at which F(0) is glycosylated. The results indicate that unlike other members of the family that replicate in cultured cells and cause systemic infections in vivo, cleavage of HeV F(0) occurs at a single lysine (reside 109) in the sequence Asp-Val-Lys- downward arrow-Leu. Although HeV genotypically resembles members of the Respirovirus and Rubulavirus genera in having potential N-linked glycosylation sites in both the F(1) and F(2) subunits, we show that phenotypically HeV may more closely resemble members of the Morbillivirus genus that contain N-linked glycans only in the F(2) subunit.

Amino Acid Sequence↗
PubMed2000

Newcastle disease virus phosphoprotein gene analysis and transcriptional editing in avian cells.

Nucleotide sequence was determined for the phosphoprotein (P) gene from 23 Newcastle disease virus (NDV) isolates representing all defined pathotypes with different chronological and geographic origins. Sequence variation, with synonymous substitutions dominating, occurred throughout the P gene. An exception was a conserved central region containing the transcriptional editing site. Four G nucleotide additions were detected in NDV P gene mRNA potentially creating alternative open reading frames. However, only one in-frame stop codon exists with a single G addition among all isolates that would allow for a potential V protein. A second potential stop codon does not exist in the P gene consensus sequence among all isolates with more than one G nucleotide addition at the editing site. This precludes a possible W protein in these isolates. A second potential alternative in-frame start site exists among all isolates that could encode a predicted X protein for NDV. Comparison of the P gene editing sites among the Paramyxovirinae and predicted P gene usage demonstrates that NDV more closely resembles the respiroviruses and morbilliviruses. Phylogenetic analysis of P gene sequences among NDV isolates demonstrates there are two clades of these viruses. One group includes viruses isolated in the US prior to 1970, while a second cluster includes virulent viruses circulating worldwide.

Amino Acid Sequence↗
PubMed2001

Identification and molecular characterization of 18 paramyxoviruses isolated from snakes.

Viral agents from 18 different snake species (families Colubridae, Viperidae, and Crotalidae) showing respiratory symptoms and neuronal disease were identified as paramyxoviruses by typical cytopathogenic effect (CPE), electron microscopy, and hemagglutination inhibition. Detailed molecular characterization of the viruses was performed by partial L- and F-gene-specific reverse transcription polymerase chain reaction (RT-PCR) and sequencing, nucleotide and amino acid sequence alignment, and phylogenetic analysis (PHYLIP). RT-PCR of the partial L-gene (566 nt) was successful for all 18 viruses; amplicons of the partial F-gene (918 nt) could be obtained in 16 cases. F- and L-sequence alignment revealed similarities to Fer de Lance virus (FDLV) ranging from 79 to 88% on a nucleotide basis, and 94 to 99% on an amino acid basis. Phylogenetic analysis of the ophidian paramyxoviruses resulted in three clusters for the L-gene sequence and corresponding clusters for the F-gene sequence, indicating no species specificity. We analyzed the F-protein of the snake paramyxoviruses, which proved to have an identical conserved motif of heptad repeat A and predicted a furin cleavage site. This uniformity distinguishes the snake virus group from the other type species of the subfamily Paramyxovirinae. For further classification, we aligned the sequences of the ophidian paramyxoviruses and members of the Paramyxoviridae, such as Sendai virus (genus Respirovirus), mumps virus (genus Rubulavirus), measles virus (genus Morbillivirus), human respiratory syncytial virus (genus Pneumovirus) (Van Regenmortel and 10 co-authors, 2000) and Hendra virus, which have recently been suggested as type species of the genus Henipavirus (Wang et al., 2000). Maximum sequence similarity was found to the partial L-gene of Sendai virus, with 56% nucleotide and 61% amino acid identity. The FDLV and Sendai virus cluster in the phylogenetic analysis of L- and F-protein regarding the Paramyxovirus type species and Hendra virus and show the closest relationship. Regarding the biological properties, the antigenic distance, and particularly the low homology of available sequences, we propose a new genus for the reptilian paramyxoviruses within the Paramyxoviridae.

Amino Acid Sequence↗
PubMed2000

The exceptionally large genome of Hendra virus: support for creation of a new genus within the family Paramyxoviridae.

An outbreak of acute respiratory disease in Hendra, a suburb of Brisbane, Australia, in September 1994 resulted in the deaths of 14 racing horses and a horse trainer. The causative agent was a new member of the family Paramyxoviridae. The virus was originally called Equine morbillivirus but was renamed Hendra virus (HeV) when molecular characterization highlighted differences between it and members of the genus Morbillivirus. Less than 5 years later, the closely related Nipah virus (NiV) emerged in Malaysia, spread rapidly through the pig population, and caused the deaths of over 100 people. We report the characterization of the HeV L gene and protein, the genome termini, and gene boundary sequences, thus completing the HeV genome sequence. In the highly conserved region of the L protein, the HeV sequence GDNE differs from the GDNQ found in almost all other nonsegmented negative-strand (NNS) RNA viruses. HeV has an absolutely conserved intergenic trinucleotide sequence, 3'-GAA-5', and highly conserved transcription initiation and termination sequences similar to those of respiroviruses and morbilliviruses. The large genome size (18,234 nucleotides), the unique complementary genome terminal sequences of HeV, and the limited homology with other members of the Paramyxoviridae suggest that HeV, together with NiV, should be classified in a new genus in this family. The large genome of HeV also fills a gap in the spectrum of genome sizes observed with NNS RNA virus genomes. As such, it provides a further piece in the puzzle of NNS RNA virus evolution.

Amino Acid Sequence↗
PubMed1980

Influenza in children. Relationship to other respiratory agents.

During the 1975-1976 respiratory disease season, influenza A/Victoria virus exceeded respiratory syncytial (RS) virus as a cause of lower respiratory tract disease (LRD) in children admitted to the hospital. This was a reversal of their usual roles in the etiology of LRD; however, the importance of influenza viruses in causing serious disease in children has been underestimated because of failure to appreciate the full spectrum of disease associated with influenza virus infections. In addition to those with LRD, several children were hospitalized with nonspecific febrile illnesses or CNS involvement. Furthermore, in the ambulatory care setting, influenza viruses were the most important cause of illness that necessitated children's being brought for medical care during a three-year period. During the peak of epidemics, influenza viruses appeared to interfere with the spread of other major respiratory viruses--particularly RS virus.

Adolescent↗
PubMed1999

The human mucus protease inhibitor and its mutants are novel defensive compounds against infection with influenza A and Sendai viruses.

Tryptase Clara, a trypsin-like protease localized exclusively in and secreted by Clara cells of the bronchial epithelium, is a prime host factor that processes viral envelope glycoproteins and determines the infectivity of influenza A and Sendai viruses (H. Kido, Y. Yokogoshi, K. Sakai, M. Tashiro, Y. Kishino, A. Fukutomi, and N. Katunuma, The Journal of Biological Chemistry, 1992, Vol. 267, pp. 13573-13579). We report here that human mucus protease inhibitor (MPI), a major inhibitor of granulocyte elastase in the lining fluid of the human respiratory tract, significantly inhibited induction of the infectivity of influenza A and Sendai viruses by tryptase Clara in vitro and multicycles of mouse-adapted influenza A virus replication in rat lungs in vivo. Recombinant MPI and the C- but not the N-terminal domain of MPI inhibited both the activity of tryptase Clara and the induction of virus infection by tryptase Clara. The 50% inhibitory concentrations of MPI and the C-terminal domain peptide (Pro50-Ala107) of MPI for tryptase Clara were 7.4 and 61.6 nM, respectively, with Sendai virus envelope glycoproteins as the substrate. Studies on deletion mutants of the C-terminal domain of MPI revealed that the minimal size of MPI required for the inhibition of tryptase Clara is the peptide Lys60-Ala107. Studies involving site-directed mutagenesis of the C-terminal domain of MPI indicated that the Leu72-Met73 site of MPI is the inhibitory site for tryptase Clara. Substitution of residue Leu72 with a basic amino acid significantly increased in the inhibitory activity of the C-terminal domain of MPI, but further substitution of residue Met73 with various amino acids in these mutants reduced the inhibitory activity. Since there is evidence suggesting that the concentration of MPI in respiratory fluid is insufficient for prevention of virus infection, the administration of MPI, the recombinant C-terminal domain of MPI, and their mutants, with residue Leu72 substituted with residues Arg72 and Lys72, may be useful for treatment of such pneumotropic virus infections.

Animals↗
PubMedDate not supplied

Paramyxovirus replication and pathogenesis. Reverse genetics transforms understanding.

A recent breakthrough in the field of nonsegmented negative strand RNA viruses (Mononegavirales), including paramyxoviruses, is the establishment of a system to recover an infectious virus entirely from complementary DNA and hence allow reverse genetics. Mutations can now be introduced into viral genomes at will and the resulting phenotypes studied as long as the introduced mutations are not lethal. This technology is being successfully applied to answer outstanding questions regarding the roles of viral components in replication and their contribution to pathogenicity, which are difficult to address using conventional virology. For instance, how the paramyxovirus accessory proteins V and C contribute to actual viral replication and pathogenesis has remained unanswered since their first description more than 20 years ago. Using Sendai virus, which causes fatal pneumonia in mice, it has been shown that the V protein is completely dispensable for viral replication in cell cultures but encodes a luxury function required for pathogenesis in vivo. The Sendai virus C proteins were also defined to be nonessential gene products which greatly contributed to replication both in vitro and in vivo. It is also now possible to design live vaccines by introducing predetermined or plausible attenuating mutations. In addition, the use of paramyxoviruses to express foreign genes has also become feasible. Paramyxovirus reverse genetics is thus renovating our understanding of viral replication and pathogenesis and will further mark an era in recombinant technology for disease prevention and gene therapy.

Animals↗
PubMed1996

Attenuation of airway hyperresponsiveness during acute viral infection using the 21-aminosteroid U-83836E in rats.

Respiratory viral infections have been associated with exacerbations of asthma in humans, and are known to produce airway obstruction and hyperresponsiveness in rats. Virus-induced airway dysfunction may result in part from inflammatory cells and their products, and agents that target these mechanisms might therefore attenuate viral airway injury. The 21-aminosteroid class of drugs has been reported to attenuate tissue injury in a variety of models, and we hypothesized that U-83836E, an orally-active aminosteroid, would prevent the development of airway dysfunction during acute viral illness. Adult rats were inoculated with either parainfluenza type 1 (Sendai) virus or sterile vehicle, treated with either U-83836E 20 mg/kg or water by oral gavage twice daily, and studied on postinoculation day 5, 6 or 7. Anesthetized, paralysed, mechanically ventilated rats were placed in a body plethysmograph for measurements of airway obstruction (resistance, dynamic compliance, eucapneic PaO2), and responsiveness to i.v. methacholine; lungs were lavaged to obtain inflammatory cells. The water-treated virus group was significantly different from the non-infected controls for all variables. Virus-induced hyperresponsiveness was attenuated (P = 0.027) by aminosteroid treatment, although airway obstruction and inflammation were not improved by the treatment. We conclude that 21-aminosteroids may protect airways from virus-induced hyperresponsiveness.

Acute Disease↗
PubMed1999

Isolation and molecular characterization of a novel cytopathogenic paramyxovirus from tree shrews.

A cytopathic infectious agent was isolated from the kidneys of an apparently healthy tree shrew (Tupaia belangeri) that had been captured in the area around Bangkok. The infectivity was propagated in Tupaia fibroblast and kidney cell cultures. Paramyxovirus-like pleomorphic enveloped particles and helical nucleocapsids were observed by electron microscopy and accordingly the infectious agent was termed Tupaia paramyxovirus (TPMV). However, no serological cross-reactions were detected between TPMV and known paramyxoviruses. For the molecular characterization of TPMV an experimental strategy that allows the random-primed synthesis of relatively large cDNA molecules from viral genomic RNA was applied. Nucleotide sequence analysis of a TPMV-specific cDNA fragment (1544 bp) revealed two nonoverlapping partial open reading frames corresponding to paramyxoviral N and P transcription units. Using modified rapid amplification of cDNA ends techniques, a substantial contiguous portion of the viral genome (4065 nt) was elucidated including the complete N and P/V/C genes. The coding strategy of TPMV as well as significant amino acid sequence homologies clearly indicates an evolutionary relationship between TPMV and members of the genus Morbillivirus. Highest homologies were detected between TPMV and Hendra virus (equine morbillivirus), which recently emerged in Australia, causing outbreaks of fatal respiratory and neurological disease in horses and humans.

Amino Acid Sequence↗
PubMed1999

Role of primary constitutive phosphorylation of Sendai virus P and V proteins in viral replication and pathogenesis.

Functional analysis of the primary constitutive phosphorylation of Sendai virus P and V proteins was performed using both in vitro and in vivo systems. Sendai virus minigenome transcription and replication in transfected cells were not significantly affected in the presence of primary phosphorylation deficient P protein (S249A, S249D, P250A) as measured by either the luciferase activity or the Northern blot analysis. Similarly, recombinant Sendai viruses lacking the primary phosphorylation in P grew to titers close to the wild-type virus in cell cultures and in the natural host of Sendai virus, the mouse. Mutant viruses showed no altered pathogenesis in mice lungs. Oligomerization of P by binding WT P or mutant P to GST-P (WT) Sepharose beads revealed that the primary phosphorylation was not crucial for P protein oligomerization. Similar to P protein primary phosphorylation, the V protein primary phosphorylation at serine249 was not essential for minigenome transcription and replication, as both WT and mutant V proteins were found equally inhibitory to the minigenome replication. These results show that the primary phosphorylation of P protein has no essential role in Sendai virus transcription, replication, and pathogenesis.

Animals↗
PubMed2001

Tioman virus, a novel paramyxovirus isolated from fruit bats in Malaysia.

A search for the natural host of Nipah virus has led to the isolation of a previously unknown member of the family Paramyxoviridae. Tioman virus (TiV) was isolated from the urine of fruit bats (Pteropus hypomelanus) found on the island of the same name off the eastern coast of peninsular Malaysia. An electron microscopic study of TiV-infected cells revealed spherical and pleomorphic-enveloped viral particles (100--500 nm in size) with a single fringe of embedded peplomers. Virus morphogenesis occurred at the plasma membrane of infected cells and morphological features of negative-stained ribonucleoprotein complexes were compatible with that of viruses in the family Paramyxoviridae. Serological studies revealed no cross-reactivity with antibodies against a number of known Paramyxoviridae members except for the newly described Menangle virus (MenV), isolated in Australia in 1997. Failure of PCR amplification using MenV-specific primers suggested that this new virus is related to but different from MenV. For molecular characterization of the virus, a cDNA subtraction strategy was employed to isolate virus-specific cDNA from virus-infected cells. Complete gene sequences for the nucleocapsid protein (N) and phosphoprotein (P/V) have been determined and recombinant N and V proteins produced in baculovirus. The recombinant N and V proteins reacted with porcine anti-MenV sera in Western blot, confirming the serological cross-reactivity observed during initial virus characterization. The lack of a C protein-coding region in the P/V gene, the creation of P mRNA by insertion of 2-G residues, and the results of phylogenetic analyses all indicated that TiV is a novel member of the genus Rubulavirus.

Amino Acid Sequence↗
PubMed2002

The V proteins of simian virus 5 and other paramyxoviruses inhibit induction of interferon-beta.

In this article we show that the paramyxovirus SV5 is a poor inducer of interferon-beta (IFN-beta). This inefficient induction is a consequence of the expression of an intact viral V protein. In the absence of the viral V protein cysteine-rich C-terminal domain, IFN-beta mRNA is strongly induced and the transcription factors NF-kappaB and IRF-3 are activated significantly. The V protein can work in isolation from SV5 to block intracellular dsRNA signaling. The mechanism of block to dsRNA signaling is distinct from that previously observed for blocking IFN signaling in that proteolysis of candidate factors cannot be detected, and furthermore, the respective blocks require distinct protein domains. Blocking of the induction of IFN-beta by dsRNA requires the C-terminal cysteine-rich domain, a feature that is highly conserved among paramyxoviruses. We demonstrate that the V proteins from other paramyxoviruses have equivalent functions and speculate that limiting the yield of IFN-beta during infection may be a general property of paramyxoviruses.

Animals↗
PubMed2002

Recovery of paramyxovirus simian virus 5 with a V protein lacking the conserved cysteine-rich domain: the multifunctional V protein blocks both interferon-beta induction and interferon signaling.

The V protein of the Paramyxovirus simian virus 5 (SV5) is a multifunctional protein containing an N-terminal 164 residue domain that is shared with the P protein and a distinct C-terminal domain that is cysteine-rich and which is highly conserved among Paramyxoviruses. We report the recovery from Vero cells [interferon (IFN) nonproducing cells] of a recombinant SV5 (rSV5) that lacks the V protein C-terminal specific domain (rSV5VDeltaC). In Vero cells rSV5VDeltaC forms large plaques and grows at a rate and titer similar to those of rSV5. In BHK or CV-1 cells rSV5VDeltaC forms small plaques and grows poorly. However, even when grown in Vero cells rSV5VDeltaC reverts to pseudo-wild-type virus in four to five passages, indicating the importance of the V protein for successful replication of SV5. Whereas rSV5 grows in many cell types with minimal cytopathic effect (CPE), rSV5VDeltaC causes extensive CPE in the same cell types. To overcome the antiviral state induced by IFN, many viruses have evolved mechanisms to counteract the effects of IFN by blocking the production of IFN and abrogating IFN signaling. Whereas rSV5 blocks IFN signaling by mediating the degradation of STAT1, rSV5VDeltaC does not cause the degradation of STAT1 and IFN signaling occurs through formation of the ISGF3 transcription complex. Furthermore, we find that rSV5 infection of cells prevents production of IFN-beta. The transcription factor IRF-3 which is required for transcription of the IFN-beta gene is not translocated from the cytoplasm to the nucleus in rSV5-infected cells. In contrast, in rSV5VDeltaC-infected cells IRF-3 is localized predominantly in the nucleus and IFN-beta is produced. By using ectopic expression of IRF-3, it was shown that after dsRNA treatment and expression of the V protein IRF-3 remained in the cytoplasm, whereas after dsRNA treatment and expression of the P protein (which lacks the C-terminal cysteine-rich domain) IRF-3 was localized predominantly in the nucleus. Thus, SV5 blocks two distinct pathways of the innate immune response, both of which require the presence of the C-terminal specific cysteine-rich domain of the multifunctional SV5 V protein.

Amino Acid Sequence↗