Protection of hamsters against experimental mumps virus (MuV) infection by antibodies raised against the MuV surface glycoproteins expressed from recombinant vaccinia virus vectors.

The fusion (F) and haemagglutinin-neuraminidase (HN) glycoproteins of mumps virus (MuV) have been produced in CV1 cells via vaccinia virus recombinants. Recombinant proteins accumulated in infected cells and were glycosylated. Upon reduction, the F protein product was completely converted into its subunits. Hamsters infected with vaccinia recombinants expressing either the F or HN proteins produced antibodies recognizing MuV antigens and neutralizing MuV infectivity in vitro. These antibodies provided protection against MuV-induced encephalitis in newborn hamsters.

Sequence analysis of the genes encoding the nucleocapsid protein and phosphoprotein (P) of phocid distemper virus, and editing of the P gene transcript.

The nucleotide and deduced amino acid sequences of two genes of phocid distemper virus (PDV) were determined by cDNA cloning and sequencing. The long open reading frame of the gene encoding the nucleocapsid (N) protein is presented. As with other morbilliviruses, the phosphoprotein (P) gene of PDV was found to be located after the 5' end of the N gene and before the 3' end of the matrix protein gene. The P gene was shown to have the capacity to encode three distinct proteins, P, V and C, in analogy to other morbilliviruses. The results presented provide evidence for editing of the PDV P mRNA transcript by insertion of G residues. When the nucleotide and deduced amino acid sequences of the N, P, V and C genes were aligned with corresponding sequences of other established members of the morbillivirus genus, compelling homology was found between PDV and canine distemper virus (CDV), whereas there was markedly less similarity between PDV and measles virus or rinderpest virus. On the basis of the alignments presented, the estimated amino acid sequence similarity between the N and P genes of PDV and CDV was 84% and 76%, respectively. These differences at the genomic level indicate that the viruses are two separate entities.

Molecular cloning and sequence analysis of human parainfluenza type 2 virus mRNA encoding the fusion glycoprotein.

A library of cDNA clones from mRNA of human parainfluenza type 2 virus (PIV2) was constructed and the nucleotide sequence of the fusion (F) glycoprotein gene determined. The F gene boundaries were obtained by primer extension sequencing on F mRNA and on viral genomic RNA. The mRNA coding for the F glycoprotein is composed of 1918 nucleotides. It contains a single large open reading frame that encodes a protein of 551 amino acids with an Mr of 59586. The predicted PIV2 F protein contains the cleavage-activation site (amino acids 101 to 106) including two Arg and two Lys residues, where the protein is cleaved by host protease into F1 and F2 subunits by analogy with other paramyxoviruses. Three hydrophobic domains are recognized, the signal peptide (amino acids 1 to 21), that is cleaved off in the mature protein, the fusion peptide (amino acids 107 to 132) at the cleavage-generated N terminus of subunit F1 and the membrane anchorage region (amino acids 486 to 513) near the C terminus of the protein. The predicted F protein has six potential glycosylation sites and 10 of the 12 Cys residues present have conserved positions as compared with those of other paramyxovirus F proteins. Primer extension sequencing on viral RNA gave the 3' end sequence as UAAAUUCU6 followed by the 5' end of the haemagglutinin-neuraminidase (HN) gene thus establishing the order of genes coding for the viral glycoproteins of PIV2 as 5'-F-HN-3'.

The mumps virus fusion protein mRNA sequence and homology among the paramyxoviridae proteins.

The complete nucleotide sequence of the fusion protein (F) mRNA of the virulent SBL-1 strain of mumps virus has been determined by sequencing cDNA clones and mRNA and confirmed by partially sequencing the genomic RNA. The mRNA was 1721 nucleotides long excluding the poly(A) sequence and had one long open reading frame which encoded a protein of 538 amino acids with a calculated Mr of 58,791. The predicted amino acid sequence had a proteolytic cleavage/activation site, Arg Arg His Lys Arg, cleavage at which yields proteins F2 and F1. The uncleaved protein contained three highly hydrophobic regions: (i) the amino-terminal signal peptide, (ii) the amino-terminal region of F1 and (iii) the carboxy-terminal membrane anchorage domain. There were seven potential N-glycosylation sites, two in F2 and five in F1. Comparison of the virulent strain F protein sequence with that of an avirulent strain of mumps virus showed a difference of 14 amino acids. Among paramyxoviruses, mumps virus fusion protein shows the highest degree of homology with the fusion proteins of simian virus 5 and Newcastle disease virus.

mRNA sequence and deduced amino acid sequence of the mumps virus small hydrophobic protein gene.

The mRNA of a putative small hydrophobic protein (SH) of mumps virus was identified in mumps virus-infected Vero cells, and its complete nucleotide sequence was determined by sequencing the genomic RNA and cDNA clones and partial sequencing of mRNA. The SH mRNA is 310 nucleotides long excluding the poly(A) and contains a single open reading frame encoding a protein of 57 amino acids with a calculated molecular weight of 6,719. The predicted protein is highly hydrophobic and contains a stretch of 25 hydrophobic amino acids near the amino terminus which could act as a membrane anchor region. There is no homology between the putative SH protein of mumps virus and the SH protein of simian virus 5, even though the SH genes are located in the same locus in the corresponding genome. One interesting observation is that the hydrophobic domain of simian virus 5 SH protein is at the carboxyl terminus, whereas that of mumps virus putative SH protein is near the amino terminus.

Molecular cloning and characterization of six genes, determination of gene order and intergenic sequences and leader sequence of mumps virus.

mRNA isolated from mumps virus-infected Vero cells was converted into cDNA and cloned into the PstI site of the plasmid pBR322. After screening with 32P-labelled cDNA synthesized from poly(A)+ RNA of uninfected or mumps virus-infected Vero cells, five different groups of virus-specific clones were obtained. The virus specificity of the clones was confirmed by Northern blot analysis, in which the cDNA inserts from the five different groups hybridized to mRNAs of about 2100, 1500, 1450, 2000 and 2200 nucleotides. By the use of oligonucleotides synthesized on the basis of sequences obtained from the five cDNA clones and mRNAs, the sequence of the intergenic and surrounding areas was determined. During genome sequencing, a separate gene was identified between the fusion protein (F) gene and the haemagglutinin-neuraminidase protein (HN) gene. Using oligonucleotides synthesized on the basis of the new gene sequence, cDNA clones with poly(A) were isolated from the cDNA library. The gene order was determined to be 3' NC-P-M-F-SH-HN-L 5' (where NC, P, M, SH, and L represent the genes for the nucleocapsid, phosphoprotein or polymerase-associated, matrix or membrane, small hydrophobic and large proteins respectively). There is one nucleotide between the P and M (A), M and F (A), and HN and L genes (G), two between the NC and P (AA) and SH and HN (3'-CG) genes, and seven between the F and SH genes (3' GAUUUUA) as intergenic sequence. The leader sequence at the 3' end of the genome has been determined by sequencing the dicistronic leader-NC mRNA using oligonucleotide primers. The sequence from the 3' terminus to the NC gene start of the mumps virus genome is similar in length (55 nucleotides) to that present in Sendai virus, Newcastle disease virus and parainfluenza virus type 3, and the first five nucleotides are conserved in all negative-stranded RNA virus genomes sequenced to date.

Protection against lethal measles virus infection in mice by immune-stimulating complexes containing the hemagglutinin or fusion protein.

The importance of each of the two surface glycoproteins of measles virus in active and passive immunization was examined in mice. Infected-cell lysates were depleted of either the hemagglutinin (H) or fusion (F) glycoprotein by using multiple cycles of immunoaffinity chromatography. The products were used to prepare immune-stimulating complexes (iscoms) containing either F or H glycoprotein. Such complexes are highly immunogenic, possibly as a result of effective presentation of viral proteins to the immune system [B. Morein, B. Sundquist, S. Höglund, K. Dalsgaard, and A. Osterhaus, Nature (London) 308:457-460, 1984]. Groups of 3-week-old BALB/c mice were inoculated with the iscom preparations. All animals developed hemolysis-inhibiting antibodies, whereas only sera of animals immunized with the iscoms containing the H glycoprotein had hemagglutination-inhibiting antibodies. Sera from animals immunized with the H or F preparation only precipitated the homologous glycoprotein in radioimmune precipitation assays. The immunized animals were challenged with a lethal dose of the hamster neurotropic variant of measles virus. Of the 7-week-old animals in the nonimmunized control group, 50% died within 10 days after challenge. No animals in the immunized groups showed symptoms of disease throughout the observation period of 3 months. Passive administration of anti-H monoclonal antibodies gave full protection against the 100% lethal acute infection with the hamster neurotropic variant of measles virus in newborn mice, whereas anti-F monoclonal antibodies failed to protect the animals. This study emphasizes that both H and F glycoproteins need to be considered in the development of measles virus subunit vaccines.

F1 polypeptides of two canine distemper virus strains: variation in the conserved N-terminal hydrophobic region.

The fusion protein of canine distemper virus was isolated by immunoadsorption from two virus strains, the rapidly growing Onderstepoort strain (forming large plaques) and the Convac vaccine strain (forming microplaques). The F1 subunits of the two fusion proteins were purified by preparative polyacrylamide gel electrophoresis. Direct amino acid sequence analysis revealed that 36-residue N-terminal regions of the proteins from the two strains are identical except at position 9, where Ala in the Convac strain is substituted by Val in the Onderstepoort strain. The two sequences show high homology with the previously determined N-terminal sequence of the F1 polypeptide of measles virus, and moderate homology with corresponding sequences of five paramyxoviruses, emphasizing the occurrence of an extensive conservation of these structures.

Measles virus hemagglutinin. Removal of the initiator methionine in the mature protein, and evidence for further processing to produce a 'ragged' end.

Measles virus hemagglutinin has been isolated by immunoadsorption. The total composition of the protein and its N-terminal amino acid sequence give data matching the structure indirectly deduced from cDNA. However, direct analysis of the hemagglutinin also shows that the mature protein is proteolytically processed and has a partly heterogeneous N-terminus. The initiator Met is removed, and non-stoichiometrically also the second residue.

Isolation and characterization of the measles virus F1 polypeptide: comparison with other paramyxovirus fusion proteins.

Measles virus fusion (F) protein has been isolated by immunoadsorption to a complex of monoclonal antibodies bound to protein A-Sepharose. The 41-kDa F1 component of the fusion protein was obtained pure in high yield by preparative SDS-polyacrylamide gel electrophoresis. The amino acid composition of the F1 chain was determined and the N-terminal sequence was analyzed for 40 residues. The structure determined is largely hydrophobic, with 24 residues of Val, Ile, Leu, Met, Phe, or Ala. Comparison with previously published data on the F1 polypeptide of Sendai virus showed considerable similarity in amino acid composition. Extensive N-terminal sequence homologies with F1 polypeptides of different paramyxoviruses are also noticed, including a nine-residue segment strictly conserved among four F1 polypeptides studied, as well as a weaker but distinct and Gly-rich sequence homology with the influenza A and B virus HA2 polypeptides. The evolutionary conservation of the N-terminal region at the site of cleavage of surface glycoproteins of the two families of myxoviruses highlights its specialized function in membrane fusion.

Purification, morphology and antigenic characterization of measles virus envelope components.

Measles virus haemagglutinin (H), fusion (F) and matrix (M) components were purified by affinity chromatography using monoclonal antibodies coupled to CNBr-activated Sepharose. H and M proteins were purified to homogeneity as determined by polyacrylamide gel electrophoresis by a single cycle of adsorption-desorption. The corresponding purification of the F protein required two cycles of adsorption-desorption. After the second adsorption an extra wash with 1 M-guanidine-HCl was employed to remove the contaminating cellular actin. Electron microscopic examination of the purified envelope proteins showed that, at pH 6.0, the H peplomers had a truncated conical shape (width 6.5 to 4 nm, length 16 nm), and the F peplomers had a club-like shape (dimensions of the oval head 6 X 9 nm, length 15 nm). Lengths of both peplomers were measured excluding their undiscernible hydrophobic part. The M component at pH 3.0 appeared as a rounded particle (diam. 8 nm, central accumulation of contrast 1.5 nm) suggested to include four to six M polypeptides. Rabbit hyperimmune sera were prepared against all three purified envelope components. These sera reacted only with the homologous antigen in radioimmunoprecipitation assays. Both antisera against the H and F components neutralized the virus and blocked virus-specific haemolysis, but only anti-H serum inhibited haemagglutination.

Epidemic outbreaks of adenovirus 7 with special reference to the pathogenicity of adenovirus genome type 7b.

Adenovirus type 7 (Ad 7) is the serotype among the 36 recognized adenovirus types which most frequently has been associated with severe illness. Three different epidemic patterns of Ad 7 infection can be distinguished: 1) the first appears during the winter among infants with median age below two years, has characteristic symptoms of high fever and pneumonia and an outcome that may be fatal: 2) the second appears in the fall among children with median age seven years, has characteristic symptoms of high fever, pneumonia, abdominal symptoms and meningism and an outcome that is favorable; 3) and the third has been seen as acute respiratory disease among military recruits. In the United States, the last mentioned outbreaks require prophylaxis in the form of a live enteric-coated vaccine. DNA restriction site mapping demonstrated the occurrence of three distinct viral entities of Ad 7, which have been designated Ad 7 prototype, Ad 7a (the vaccine strain) and the Ad 7b genome type. In the present study, 36 isolates obtained from outbreaks with the first and the second epidemic patterns were analyzed by restriction endonucleases Bam HI and Sma I. All were identified as the newly recognized Ad 7b genome type. It is concluded that this genome type is responsible for a large portion of the severe infections caused by Ad 7. The epidemic nature of Ad 7 and the severe illness noted among infants indicate that vaccination of institutionalized infants could be considered during years when Ad 7 epidemics appear.

Demonstration of three different subtypes of adenovirus type 7 by DNA restriction site mapping.

Restriction site mapping of the genomes of eight different isolates of adenovirus serotype 7 (Ad7) has been performed with six different restriction endonucleases. In this analysis, 37 different restriction sites were localized. Three distinctly different cleavage patterns of the genomes of the Ad7 strains were observed. These strains could not be distinguished by serological techniques. The following three subtypes were defined on the basis of their restriction site patterns: the Ad7 prototype, represented by strain Gomen originally isolated from a case of pharyngitis; subtype Ad7a, represented by the Ad7 vaccine strain and strains isolated from undifferentiated respiratory disease and from a healthy carrier; and a third subtype of Ad7, represented by three strains which were isolated from Swedish patients, all having pronounced clinical symptoms indicating severe systemic infection. A comparison of the restriction site maps of the protype of Ad3 and the three subtypes of Ad7 indicated greater differences in the position of restriction sites between strains of Ad7 than between strains of the two serotypes. This technique is consequently recommended to obtain a more precise definition of distinct entities of viruses.