A newly discovered human pneumovirus isolated from young children with respiratory tract disease

From 28 young children in the Netherlands, we isolated a paramyxovirus that was identified as a tentative new member of the Metapneumovirus genus based on virological data, sequence homology and gene constellation. Previously, avian pneumovirus was the sole member of this recently assigned genus, hence the provisional name for the newly discovered virus: human metapneumovirus. The clinical symptoms of the children from whom the virus was isolated were similar to those caused by human respiratory syncytial virus infection, ranging from upper respiratory tract disease to severe bronchiolitis and pneumonia. Serological studies showed that by the age of five years, virtually all children in the Netherlands have been exposed to human metapneumovirus and that the virus has been circulating in humans for at least 50 years.

Bats host major mammalian paramyxoviruses

The large virus family Paramyxoviridae includes some of the most significant human and livestock viruses, such as measles-, distemper-, mumps-, parainfluenza-, Newcastle disease-, respiratory syncytial virus and metapneumoviruses. Here we identify an estimated 66 new paramyxoviruses in a worldwide sample of 119 bat and rodent species (9,278 individuals). Major discoveries include evidence of an origin of Hendra- and Nipah virus in Africa, identification of a bat virus conspecific with the human mumps virus, detection of close relatives of respiratory syncytial virus, mouse pneumonia- and canine distemper virus in bats, as well as direct evidence of Sendai virus in rodents. Phylogenetic reconstruction of host associations suggests a predominance of host switches from bats to other mammals and birds. Hypothesis tests in a maximum likelihood framework permit the phylogenetic placement of bats as tentative hosts at ancestral nodes to both the major Paramyxoviridae subfamilies (Paramyxovirinae and Pneumovirinae). Future attempts to predict the emergence of novel paramyxoviruses in humans and livestock will have to rely fundamentally on these data.

The perpetuation of orthomyxoviruses and paramyxoviruses in Canadian waterfowl

A longitudinal survey of viruses in feral ducks from 1976 to 1978 in the Vermillion area of Alberta, Canada, has shown that influenza A viruses and paramyxoviruses are present year after year in these apparently healthy ducks. Influenza viruses were isolated most frequently each year from mallards, pintails, and blue-winged teals, but were not restricted to these species. During the 3-year survey, 1262 influenza viruses were isolated from 4827 ducks, revealing the high incidence of influenza infection, a finding which contrasts with the very low incidence found in ducks during migration through Tennessee.Many different influenza A viruses were detected in the ducks, including 27 different combinations of hemagglutinin and neuraminidase subtypes. These viruses encompass all but one of the known hemagglutinin and neuraminidase subtypes. The virus subtypes in the ducks varied from year to year; however, 6 of these 27 subtypes were present every year. The predominant subtype changed from Hav7Neq2 in 1976–1977 to Hav6N2 in 1978. Antigenic comparisons of current and previous Hav6 viruses isolated from ducks, turkeys, and a shearwater showed that antigenic drift occurs in avian influenza viruses.Paramyxoviruses occur in the Canadian ducks at a much lower frequency than influenza viruses; in 3 years, 69 paramyxoviruses were isolated and included two types: lentogenic NDV and Duck/Mississippi/75.These longitudinal studies indicate that the feral ducks in the study area of Canada are a perpetual reservoir of diverse influenza A viruses and paramyxoviruses.

ICTV Virus Taxonomy Profile: Paramyxoviridae

The family Paramyxoviridae consists of large enveloped RNA viruses infecting mammals, birds, reptiles and fish. Many paramyxoviruses are host-specific and several, such as measles virus, mumps virus, Nipah virus, Hendra virus and several parainfluenza viruses, are pathogenic for humans. The transmission of paramyxoviruses is horizontal, mainly through airborne routes; no vectors are known. This is a summary of the current International Committee on Taxonomy of Viruses (ICTV) Report on the family Paramyxoviridae. which is available at ictv.global/report/paramyxoviridae.

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.

Paramyxovirdae

Iit is proposed that the family paramyxovirdae shall comprise three genera: paramyxovirus, Morbillivirus, and Pneumovirus.

Significant differences in nucleocapsid morphology within the Paramyxoviridae

Nucleocapsid (N) proteins from representative viruses of three genera within the Paramyxoviridae were expressed in insect cells using recombinant baculoviruses. RNA-containing structures, which appear morphologically identical to viral nucleocapsids, were isolated and subsequently imaged under a transmission electron microscope. Analysis of these images revealed marked differences in nucleocapsid morphology among the genera investigated, most notably between viruses of the Paramyxovirinae and the Pneumovirinae subfamilies. Helical pitch measurements were made, revealing that measles virus (MV, a Morbillivirus within the subfamily Paramyxovirinae) N protein produces helices that adopt multiple conformations with varying degrees of flexibility, while that of the Rubulavirus simian virus type 5 (SV5, subfamily Paramyxovirinae) produces more rigid structures with a less heterogeneous pitch distribution. Nucleocapsids produced by respiratory syncytial virus (RSV, subfamily Pneumovirinae) appear significantly narrower than those of MV and SV5 and have a longer pitch than the most extended form of MV. In addition to helical nucleocapsids, ring structures were also produced, image analysis of which has demonstrated that rings assembled from MV N protein consist of 13 subunits. This is consistent with previous reports that Sendai virus nucleocapsids have 13.07 subunits per turn. It was determined, however, that SV5 subnucleocapsid rings have 14 subunits, while rings derived from the radically different RSV nucleocapsid have been found to contain predominantly 10 subunits.

Comparison of two morbilliviruses isolated from seals during outbreaks of distemper in north west Europe and Siberia

Recently morbilliviruses were isolated from harbour seals (Phoca vitulina) in North West Europe (phocid distemper virus-1: PDV-1) and from Baikal seals (Phoca sibirica) in Siberia (phocid distemper virus-2: PDV-2) during outbreaks of severe disease which resembled distemper in dogs. PDV-1 and PDV-2 were passaged in SPF dogs, in which they caused distemper-like disease symptoms, and were subsequently passaged in Vero cells in which they caused cytopathic changes. PDV-1, PDV-2, and canine distemper virus (CDV) were compared with respect to their biological, morphological, physical, protein chemical, and antigenic properties. It was concluded that PDV-1 should be considered a newly recognized member of the genus Morbillivirus, whereas PDV-2 proved to be quite similar if not identical to CDV.

The evolutionary and epidemiological dynamics of the paramyxoviridae

Paramyxoviruses are responsible for considerable disease burden in human and wildlife populations: measles and mumps continue to affect the health of children worldwide, while canine distemper virus causes serious morbidity and mortality in a wide range of mammalian species. Although these viruses have been studied extensively at both the epidemiological and the phylogenetic scales, little has been done to integrate these two types of data. Using a Bayesian coalescent approach, we infer the evolutionary and epidemiological dynamics of measles, mumps and canine distemper viruses. Our analysis yielded data on viral substitution rates, the time to common ancestry, and elements of their demographic history. Estimates of rates of evolutionary change were similar to those observed in other RNA viruses, ranging from 6.585 to 11.350 x 10(-4 )nucleotide substitutions per site, per year. Strikingly, the mean Time to the Most Recent Common Ancestor (TMRCA) was both similar and very recent among the viruses studied, ranging from only 58 to 91 years (1908 to 1943). Worldwide, the paramyxoviruses studied here have maintained a relatively constant level of genetic diversity. However, detailed heterchronous samples illustrate more complex dynamics in some epidemic populations, and the relatively low levels of genetic diversity (population size) in all three viruses is likely to reflect the population bottlenecks that follow recurrent outbreaks.

Characterization of morbilliviruses isolated from dolphins and porpoises in Europe

A previously unidentified morbillivirus was isolated from two harbour porpoises (Phocoena phocoena) that had died in the Dutch Waddensea (North Sea) in 1990. This porpoise morbillivirus (PMV) and a dolphin morbillivirus (DMV), which had recently caused a heavy mortality in Mediterranean striped dolphins (Stenella coeruleoalba), were compared antigenically with other members of the genus Morbillivirus, including the newly recognized phocine distemper virus type 1. DMV and PMV proved to be similar but distinct morbillivurses, closely related to rinderpest virus and peste-des-petitsruminants virus. Cell cultures of cetacean, pinniped, ruminant and canine origin showed a different pattern of susceptibility to DMV and PMV infection. Ruminants and dogs proved to be susceptible to experimental infection with DMV and PMV, which both caused a transient leukopenia most pronounced in the ruminants. Pre-exposure of dogs to DMV and PMV protected them from developing CDV viraemia and clinical signs upon challenge infection with virulent CDV. A serological survey among stranded animals of different cetacean species in Europe indicated that infections with DMV- and PMV-like morbilliviruses are not uncommon among these aquatic mammals.

The antigenic relationship between measles, canine distemper and rinderpest viruses studied with monoclonal antibodies

Monoclonal antibodies (MAbs) were used to delineate the antigenic relationship between the three morbillivirus types: measles virus (MV), canine distemper virus (CDV) and rinderpest virus (RPV). Panels of six to 31 MAbs against the haemagglutinin (H), fusion (F), nucleocapsid protein (NP), phosphoprotein (P) and matrix (M) proteins of MV and the H, F, NP and P proteins of CDV were employed. Nine strains of MV, three strains of CDV and four strains of RPV were examined by radioimmunoprecipitation assay and immune fluorescence for reactivity with the heterologous MAbs. Overall, the NP and in particular the F proteins of the morbilliviruses showed a high degree of epitopic homology; the P and M proteins showed a partial epitopic homology, with the greatest variation between the M proteins of CDV and MV; the H proteins showed a low degree of epitopic homology and then only between MV and RPV. These data indicate that the major cross-protecting antigen in heterotypic vaccination amongst morbilliviruses is the F antigen. The epitopic relationships found between morbilliviruses as identified by the MAbs were classified as follows. (i) Group-specific epitopes were present on all strains of the three morbillivirus types. (ii) Group-cross-reactive epitopes were present on only some of the strains from each morbillivirus type (these epitopes identified the presence of intratypic strain variation in all proteins of all three virus types). (iii) Type-specific epitopes, i.e. MV unique or CDV unique, were found only on the homologous morbillivirus type. (iv) CDV-RPV intertypic and MV-RPV intertypic epitopes were, respectively, epitopes shared by CDV and RPV but not with any MV strain, and epitopes shared by MV and RPV but not with any CDV strain. These cross-reactivities and type-specific reactions were obtained with the internal viral proteins (M, P and NP). The epitopes of the F proteins were mainly group-specific and no CDV-RPV or MV-RPV intertypic epitopes were found. The epitopes of the H protein were either type-specific or MV-RPV intertypic. These data support the proposed evolutionary relationship between the morbilliviruses.

The complete genome sequence of J virus reveals a unique genome structure in the family Paramyxoviridae

J virus (J-V) was isolated from feral mice (Mus musculus) trapped in Queensland, Australia, during the early 1970s. Although studies undertaken at the time revealed that J-V was a new paramyxovirus, it remained unclassified beyond the family level. The complete genome sequence of J-V has now been determined, revealing a genome structure unique within the family Paramyxoviridae. At 18,954 nucleotides (nt), the J-V genome is the largest paramyxovirus genome sequenced to date, containing eight genes in the order 3'-N-P/V/C-M-F-SH-TM-G-L-5'. The two genes located between the fusion (F) and attachment (G) protein genes, which have been named the small hydrophobic (SH) protein gene and the transmembrane (TM) protein gene, encode putative proteins of 69 and 258 amino acids, respectively. The 4,401-nt J-V G gene, much larger than other paramyxovirus attachment protein genes sequenced to date, encodes a putative attachment protein of 709 amino acids and distally contains a second open reading frame (ORF) of 2,115 nt, referred to as ORF-X. Taken together, these novel features represent the most significant divergence to date from the common six-gene genome structure of Paramyxovirinae. Although genome analysis has confirmed that J-V can be classified as a member of the subfamily Paramyxovirinae, it cannot be assigned to any of the five existing genera within this subfamily. Interestingly, a recently isolated paramyxovirus appears to be closely related to J-V, and preliminary phylogenetic analyses based on putative matrix protein sequences indicate that these two viruses will likely represent a new genus within the subfamily Paramyxovirinae.

Pneumovirus-like characteristics of the mRNA and proteins of turkey rhinotracheitis virus

Electronmicroscopy has indicated that turkey rhinotracheitis virus (TRTV), the causative agent of an acute respiratory disease in turkeys, is a member of the Paramyxoviridae family. To determine if TRTV belongs to one of the three defined genera of this family (Paramyxovirus, Morbillivirus and Pneumovirus) we have analysed the RNA and proteins induced during replication of TRTV in Vero cells. Following replication in the presence of actinomycin D 10 polyadenylated RNA bands, ranging in Mr from 0.22 to 2.0 X 10(6), were detected in infected cells; some bands probably contained 2 or more RNA species. Viral proteins were studied after radiolabelling in the presence of [35S]methionine and [3H]glucosamine. Comparison of the polypeptides in mock-infected and infected cells, virions and nucleocapsids and after lentil-lectin chromatography and immunoprecipitation revealed seven virus-specific polypeptides (p), some of which were glycosylated (gp): gp82 (Mr 82K), gp68, gp53, gp15, p43, p40 and p35. These are considered to be analogous to the large glycopolypeptide (HN, H and G), fusion protein precursor F0, the F protein cleavage products F1 and F2, nucleocapsid (N), phosphorylated (P) and matrix (M) polypeptides, respectively, of the Paramyxoviridae. Two other polypeptides (Mr 200K and 22K) were also detected, as was a glycopolypeptide of Mr 97K, probably related to gp82. Tunicamycin inhibited glycosylation of gp53 and gp15 but gp82 was little affected, most glycans still being present on a glycopolypeptide of approximately 79K. This finding, indicating that gp82 has mostly O-linked glycans, considered with the mRNA profile and the molecular weight of the N protein shows that of the three genera in this family, TRTV most closely resembles the Pneumovirus genus.

Comparison of the deduced matrix and fusion protein sequences of equine morbillivirus with cognate genes of the Paramyxoviridae

The nucleotide sequence of the matrix protein of equine morbillivirus (EMV) was determined to be 1062 nucleotides and coded for a deduced protein of M(r) 40148 having a net charge of + 19 at neutral pH. The matrix protein gene was separated from the P and F genes by intercistronic regions of 546 and 469 nucleotides, respectively. The nucleotide sequence which coded for the F protein was 1641 nucleotides and coded for a deduced protein of 546 amino acids having an M(r) of 60,447 and a charge + 4 at neutral pH. Partial sequence information was also determined for the P/V proteins. M, P and F protein sequence comparisons revealed that a greater homology existed between EMV and known members of the morbillivirus genus than with other members of the Paramyxoviridae and that this homology resided within the central half of the protein for the fusion protein, the C-terminal half of the matrix protein and at certain sites with the P protein. Far greater homology was seen between the morbilliviruses and EMV than for the other paramyxoviridae. It was inferred from phylogenetic analyses that EMV was a distantly related member of the morbillivirus genus. A conserved sequence of 18 nucleotides (assumed to be the transcriptional editing site) was present in the P gene of EMV. Insertion of a single nucleotide residue within this site generated the C-terminus of a V-like, cysteine rich protein. Likewise, a conserved 'CTT' intergenic region presumed to be the transcription termination and polyadenylation signal was present in EMV between the P-M-F genes. The close sequence homology of these sites with that of morbilliviruses also inferred that EMV was a member of the morbillivirus genus.

Comparative sequence analyses of sixteen reptilian paramyxoviruses

Viral genomic RNA of Fer-de-Lance virus (FDLV), a paramyxovirus highly pathogenic for reptiles, was reverse transcribed and cloned. Plasmids with significant sequence similarities to the hemagglutinin-neuraminidase (HN) and polymerase (L) genes of mammalian paramyxoviruses were identified by BLAST search. Partial sequences of the FDLV genes were used to design primers for amplification by nested polymerase chain reaction (PCR) and sequencing of 518-bp L gene and 352-bp HN gene fragments from a collection of 15 previously uncharacterized reptilian paramyxoviruses. Phylogenetic analyses of the partial L and HN sequences produced similar trees in which there were two distinct subgroups of isolates that were supported with maximum bootstrap values, and several intermediate isolates. Within each subgroup the nucleotide divergence values were less than 2.5%, while the divergence between the two subgroups was 20-22%. This indicated that the two subgroups represent distinct virus species containing multiple virus strains. The five intermediate isolates had nucleotide divergence values of 11-20% and may represent additional distinct species. In addition to establishing diversity among reptilian paramyxoviruses, the phylogenetic groupings showed some correlation with geographic location, and clearly demonstrated a low level of host species-specificity within these viruses.

The classification of viruses infecting the respiratory tract

Following the boom in respiratory virology in the 1960s, species of rhinoviruses, coronaviruses, enteroviruses, adenoviruses, parainfluenza viruses and respiratory syncytial virus were added to influenza and measles viruses as causes of respiratory tract infection. In restricted patient groups, such as the immunocompromised, members of the family of herpesviruses including herpes simplex, cytomegalovirus, varicella-zoster virus, Epstein-Barr virus and human herpes virus 6 have also been associated with respiratory disease. This list of pathogens was extended last year with the discovery of a novel virus, the human metapneumovirus. More than 200 antigenically distinct viruses have been documented as causes of sporadic or epidemic respiratory infections in infants, children and adults. However, this varied and diverse group can be divided among six distinct families. Understanding some of the basic biology of these families gives an insight into possible strategies for diagnosis, control and therapy.

Complete genome sequence of Fer-de-Lance virus reveals a novel gene in reptilian paramyxoviruses

The complete RNA genome sequence of the archetype reptilian paramyxovirus, Fer-de-Lance virus (FDLV), has been determined. The genome is 15,378 nucleotides in length and consists of seven nonoverlapping genes in the order 3' N-U-P-M-F-HN-L 5', coding for the nucleocapsid, unknown, phospho-, matrix, fusion, hemagglutinin-neuraminidase, and large polymerase proteins, respectively. The gene junctions contain highly conserved transcription start and stop signal sequences and tri-nucleotide intergenic regions similar to those of other Paramyxoviridae. The FDLV P gene expression strategy is like that of rubulaviruses, which express the accessory V protein from the primary transcript and edit a portion of the mRNA to encode P and I proteins. There is also an overlapping open reading frame potentially encoding a small basic protein in the P gene. The gene designated U (unknown), encodes a deduced protein of 19.4 kDa that has no counterpart in other paramyxoviruses and has no similarity with sequences in the National Center for Biotechnology Information database. Active transcription of the U gene in infected cells was demonstrated by Northern blot analysis, and bicistronic N-U mRNA was also evident. The genomes of two other snake paramyxovirus genotypes were also found to have U genes, with 11 to 16% nucleotide divergence from the FDLV U gene. Pairwise comparisons of amino acid identities and phylogenetic analyses of all deduced FDLV protein sequences with homologous sequences from other Paramyxoviridae indicate that FDLV represents a new genus within the subfamily Paramyxoviridae. We suggest the name Ferlavirus for the new genus, with FDLV as the type species.

A family-wide RT-PCR assay for detection of paramyxoviruses and application to a large-scale surveillance study

Family-wide molecular diagnostic assays are valuable tools for initial identification of viruses during outbreaks and to limit costs of surveillance studies. Recent discoveries of paramyxoviruses have called for such assay that is able to detect all known and unknown paramyxoviruses in one round of PCR amplification. We have developed a RT-PCR assay consisting of a single degenerate primer set, able to detect all members of the Paramyxoviridae family including all virus genera within the subfamilies Paramyxovirinae and Pneumovirinae. Primers anneal to domain III of the polymerase gene, with the 3′ end of the reverse primer annealing to the conserved motif GDNQ, which is proposed to be the active site for nucleotide polymerization. The assay was fully optimized and was shown to indeed detect all available paramyxoviruses tested. Clinical specimens from hospitalized patients that tested positive for known paramyxoviruses in conventional assays were also detected with the novel family-wide test. A high-throughput fluorescence-based RT-PCR version of the assay was developed for screening large numbers of specimens. A large number of samples collected from wild birds was tested, resulting in the detection of avian paramyxoviruses type 1 in both barnacle and white-fronted geese, and type 8 in barnacle geese. Avian metapneumovirus type C was found for the first time in Europe in mallards, greylag geese and common gulls. The single round family-wide RT-PCR assay described here is a useful tool for the detection of known and unknown paramyxoviruses, and screening of large sample collections from humans and animals.

Characterization of a virus associated with turkey rhinotracheitis

A virus associated with turkey rhinotracheitis was purified and its morphology and structural polypeptides were compared with those of the bovine, human and murine members of the genus Pneumovirus. The isolate possessed surface projections 13 to 14 nm in length and a helical nucleocapsid 14 nm in diameter with a pitch of 7 nm. Approximately seven presumed viral polypeptides were observed. Their apparent molecular weights were 200 x 10(3) (200K), 84K, 54K, 42K, 37K, 31K and 14K; two of these, the 84K and 54K polypeptides, were glycosylated. The virus was shown to possess many features that were similar to established pneumoviruses and can therefore be regarded as a possible member of this genus.

Complete genome sequence of avian paramyxovirus type 3 reveals an unusually long trailer region

The complete genome sequence was determined for prototype parakeet/Netherlands/449/75 strain of avian paramyxovirus (APMV) serotype 3. The genome is 16,272 nucleotides (nt) in length, consisting of six non-overlapping genes in the order of 3'-N-P/V/W-M-F-HN-L-5', with intergenic regions of 31-63nt. APMV-3 genome follows the "rule of six" and is the largest among the avian paramyxoviruses reported to date, with a trailer region of 707nt, the longest in the family Paramyxoviridae. The cleavage site of F protein, A-R-P-R-G-R downward arrowL, does not conform to the preferred cleavage site of the ubiquitous cellular protease furin. Therefore, exogenous protease was needed for replication in vitro. Alignment and phylogenetic analysis of the predicted amino acid sequences of strain Netherlands proteins with the cognate proteins of viruses of all of the five genera of family Paramyxoviridae showed that APMV-3 strain Netherlands is more closely related to APMV-1 than APMV-6.

Characterization of paramyxoviruses isolated from penguins in Antarctica and sub-Antarctica during 1976-1979

Nine paramyxovirus isolates obtained from penguins were tested for antigenic relationships amongst themselves and to other avian paramyxoviruses. One of the isolates was shown to be a lentogenic Newcastle disease virus (NDV), i.e., of PMV-1 serotype. By serological tests and analysis of structural polypeptides the other penguin isolates could be placed into three groups. No relationship with other avian paramyxoviruses could be determined except that six of the penguin viruses, representing two of the groups, showed reaction with a monoclonal antibody raised against NDV Ulster 2C and three of the isolates, representing one of the penguin groups, also reacted with another PMV-1 directed monoclonal antibody.

RNA-dependent RNA polymerase gene analysis of worldwide Newcastle disease virus isolates representing different virulence types and their phylogenetic relationship with other members of the paramyxoviridae

Nucleotide sequence was determined for the RNA-dependent RNA polymerase (L) gene of 16 Newcastle disease virus (NDV) isolates from diverse geographic and chronological origins. The observed consensus amino acid sequence conformed to the six domains previously identified among paramyxovirus L proteins, and the putative 749QGDNQ753 active site was strictly conserved among all isolates. Analysis of predicted amino acid sequences allowed us to identify a sequencing error in the previously reported L genes for NDV. The correct sequences reported herein provided a more accurate alignment with predicted l-amino acid sequences of other paramyxoviruses. Comparison of L gene coding sequences among isolates revealed that synonymous substitutions dominated non-synonymous substitutions, as observed previously with other NDV genes. However, the overall substitution rate was lower than other genes examined making the L gene the most conserved of the NDV genome. Phylogenetic analysis of L genes among NDV isolates was consistent with previous results that suggested the existence of two major lineages. One group contained strains isolated in North America prior to 1970 and included virulent and vaccine strains, while the second group included virulent viruses isolated worldwide. A comparison of the NDV L coding sequences to other Paramyxoviridae illustrated the unique clustering of the avian-specific paramyxoviruses, further justifying the newly created Avulavirus genus.

Immunological interrelationships among human and non-human paramyxoviruses revealed by immunoprecipitation

Antigenic interrelationships among paramyxoviruses were examined by immunoprecipitation of isotope-labelled virus-infected cell lysates with specific antisera against virions or virus components. Sendai virus, human parainfluenza virus type 1 (Pa-1) and human parainfluenza virus type 3 (Pa-3) belonged to one antigenic group, and human parainfluenza virus type 2 (Pa-2), human parainfluenza virus type 4 (Pa-4), mumps virus (MuV) and simian virus 5 to a second group. Furthermore, the human paramyxoviruses Pa-1, Pa-2, Pa-3, Pa-4 and MuV formed a single antigenic group which overlapped the above groups. Although Newcastle disease virus (NDV) belonged to a separate group it showed some cross-reaction with the human paramyxoviruses. In particular, certain batches of anti-NDV antisera reacted with the fusion (F) polypeptide of Pa-2 and the reciprocal reaction of anti-Pa-2 antiserum with NDV F was also found. The nucleoprotein showed the broadest cross-reactions among these paramyxoviruses, whereas the matrix polypeptide exhibited antigenic individuality. The nucleoprotein of MuV was most cross-reactive. Pa-2 haemagglutinin-neuraminidase (HN) and anti-MuV HN serum showed cross-reactivity with various antisera and antigens.

Isolation and properties of viruses from poultry in Hong Kong which represent a new (sixth) distinct group of avian paramyxoviruses

Eight viruses isolated in Hong Kong were shown to be serologically related. One was obtained from the tracheal swab of a chicken and four were from cloacal swabs of ducks sampled at a poultry dressing plant. Three isolations were made from samples taken at a duck farm: two from pond water and one from faeces. Representatives of these isolates were shown to be paramyxoviruses but were serologically distinct from other avian and mammalian paramyxoviruses by haemagglutination inhibition and neuraminidase inhibition tests. Slight variations were seen in the properties of three isolates examined in detail. All three were apathogenic for chickens. The structural polypeptides of one isolate, PMV-6/duck/Hong Kong/199/77, were examined by SDS-polyacrylamide gel electrophoresis. Seven polypeptides were detected, with mol. wt. 180000, 76000, 60000, 55000, 51000, 48000 and 40000. The isolates represent a sixth serologically distinct avian paramyxovirus group.