The fusion and hemagglutinin-neuraminidase glycoproteins of human parainfluenza virus 3 are both required for fusion

Recombinant vaccinia viruses, VF and VHN, expressing the fusion (F) and hemagglutinin-neuraminidase (HN) glycoproteins of human parainfluenza virus 3 (HPIV3) were constructed. Infection of HeLa T4 cells with VF and VHN led to the synthesis of glycoproteins, with the correct apparent molecular weights, that were recognized by monoclonal antibodies specific for HPIV3F and HN. The HN glycoprotein was present on the surface of cells infected with VHN and these cells demonstrated both hemadsorbing and neuraminidase activities. The F glycoprotein was present in cleaved and uncleaved forms and was also expressed on the surface of VF-infected cells. Fusion activity, however, as evidenced by syncytium formation and lysis of human erythrocytes, could only be demonstrated when HeLa T4 cells were coinfected with VF and VHN. Fusion events that are mediated by HPIV3, therefore, require both the F and HN glycoproteins.

Enzyme activities in four different forms of human immunodeficiency virus 1 pol gene products

Five cassettes of the pol gene of human immunodeficiency virus 1 were constructed and inserted under the control of the polyhedrin gene promoter of Autographa californica nuclear polyhedrosis virus by homologous recombination. The first cassette polF contains the full-length pol open reading frame; the second cassette pol100 starts with the first AUG codon of the pol gene and deletes 103 amino acids from the amino terminus of the pol gene product; the third cassette pol97 deletes the entire protease coding sequence; the fourth cassette pol66 deletes both the protease and endonuclease/integrase coding sequences; and the fifth cassette pol51 contains the reverse transcriptase coding sequences plus 39 3'-terminal nucleotides of the RNase H coding sequences. We have expressed these five forms of the pol gene in Spodoptera frugiperda SF9 cells and have analyzed for both reverse transcriptase and RNase H activities. The polF construct expressed several processed forms, 66 kDa, 51 kDa, and 34 kDa proteins, that were detected only by Western blot. In contrast, pol100, pol97, pol66, and pol51 products were expressed at high levels and were readily detectable in gels by staining. The levels of expression of these four products were estimated to be greater than 150 mg/liter of culture (5 x 10(8) cells). Activity gel analyses showed that the pol100, pol97, pol66, and pol51 products possess reverse transcriptase activity; however, only pol97 and pol66 have RNase H activity. Our results demonstrate that many forms, including partially cleaved forms of human immunodeficiency virus 1 pol gene products, possess reverse transcriptase activity but only certain forms have RNase H activity.

Numerous transitions in human parainfluenza virus 3 RNA recovered from persistently infected cells

The nucleotide sequences at the 3'-termini of human parainfluenza virus 3 (HPIV3) genomic RNAs recovered from two lines of persistently infected LLC-MK2 cells were determined following PCR amplification. After 29 months of persistence the 3'-end of the HPIV3 genome was found to be highly mutated. Interestingly, the only types of nucleotide changes observed were U to C and A to G transitions. Both U to C and A to G transitions were present on individual RNA molecules. The data indicate that biased hypermutational activity leading to U To C and A to G mutations operates in cultured cells during persistent HPIV3 infections.

Molecular characterization of the M genomic segment of the Seoul 80-39 virus; nucleotide and amino acid sequence comparisons with other hantaviruses reveal the evolutionary pathway

The genomic M segment of Seoul 80-39 virus was characterized by cloning and nucleotide sequence analysis. The virion M RNA segment is 3651 nucleotides long with the 3' and 5' terminal sequences inversely complementary for 20 bases. A single open reading frame was detected in the viral complementary-sense RNA which can encode a polypeptide of 1133 amino acids. The Seoul 80-39 virus M segment was compared with the M segments of related viruses, Hantaan 76-118, Hallnas B1 and Sapporo Rat (SR-11) virus. Our results demonstrate a significant similarity between M RNA segments of the Seoul 80-39, Hantaan 76-118, Hallnas B1 and SR-11 viruses. The degree of conservation of both nucleic acid and protein sequences between these viruses reveals a close evolutionary relationship. Furthermore, it is evident that the serotypic profile of hantaviruses is determined by the rodent host species from which the virus was isolated and not by the geographical area.

Nucleotide sequence and coding capacity of the large (L) genomic RNA segment of Seoul 80-39 virus, a member of the hantavirus genus

The nucleotide sequence of the large (L) genomic RNA segment of Seoul 80-39 virus was determined from overlapping cDNA clones. The virion L RNA segment is 6530 nucleotides long. The 3' and 5' terminal sequences are inversely complementary for 15 bases. The viral complementary-sense RNA contains a single open reading frame from an AUG codon at nucleotide position 37-39 to a UAA stop codon at nucleotide position 6490-6492. This ORF could encode a polypeptide of 2151 amino acids (246,662 kDa) which likely corresponds to the L protein detected in purified viral particles (Elliott et al., 1984) and is assumed to be an RNA-dependent RNA polymerase molecule (Schmaljohn and Dalrymple, 1983). Comparison of the L protein of the Seoul 80-39 virus with the polymerase proteins encoded by other negative-stranded RNA viruses revealed 44% similarity only with the part of the Bunyamwera virus L protein (Elliott, 1989) and a very weak homology with the PB1 protein of influenza virus.

Natural mouse and human antibodies bind to a peptide derived from a germline VH chain. Evidence for evolutionary conserved self-binding locus

Murine antibodies derived from the V1 S107/T15 germline structure combined with Vk 22 L chains express the property of self-binding. Previous studies have shown that the self-binding is mediated by the Fab fragment involving structures of the hapten binding site. The molecular locus of self-binding has also been identified by showing that a peptide derived from the CDR2/FR3 region of the V1 S107 H chain inhibits self-binding. We have addressed the question of whether self-binding antibodies interact with peptides that inhibit self-binding. We found that labeled TEPC15 (T15) binds to immobilized VH (50-73) peptide; the peptide binding is specific because different CDR peptides and other unrelated peptides do not inhibit this binding. Furthermore, the hapten phosphorylcholine is a potent inhibitor for the T15-peptide binding. We have demonstrated the presence of naturally occurring antibodies that bind to the T15H(50-73) peptide in the sera of different strains of mice and also in humans, indicating that the CDR2/FR3 sequence of T15 is a conserved Id determining region. We have isolated peptide-specific antibodies from pooled normal human Ig preparations. Human anti-peptide antibodies have self-binding properties similar to their murine counterparts. This interspecies conserved peptide binding of antibodies that are self-binding indicates the existence of an evolutionarily important and biologically active site.

Natural mouse and human antibodies bind to a peptide derived from a germline VH chain. Evidence for evolutionary conserved self-binding locus

Murine antibodies derived from the V1 S107/T15 germline structure combined with Vk 22 L chains express the property of self-binding. Previous studies have shown that the self-binding is mediated by the Fab fragment involving structures of the hapten binding site. The molecular locus of self-binding has also been identified by showing that a peptide derived from the CDR2/FR3 region of the V1 S107 H chain inhibits self-binding. We have addressed the question of whether self-binding antibodies interact with peptides that inhibit self-binding. We found that labeled TEPC15 (T15) binds to immobilized VH (50-73) peptide; the peptide binding is specific because different CDR peptides and other unrelated peptides do not inhibit this binding. Furthermore, the hapten phosphorylcholine is a potent inhibitor for the T15-peptide binding. We have demonstrated the presence of naturally occurring antibodies that bind to the T15H(50-73) peptide in the sera of different strains of mice and also in humans, indicating that the CDR2/FR3 sequence of T15 is a conserved Id determining region. We have isolated peptide-specific antibodies from pooled normal human Ig preparations. Human anti-peptide antibodies have self-binding properties similar to their murine counterparts. This interspecies conserved peptide binding of antibodies that are self-binding indicates the existence of an evolutionarily important and biologically active site.

Expression of gag precursor protein and secretion of virus-like gag particles of HIV-2 from recombinant baculovirus-infected insect cells

A recombinant baculovirus carrying the gag gene but lacking the protease coding sequences of human immunodeficiency virus type 2 (HIV-2) has been constructed. When this recombinant baculovirus is used to infect insect cells, a high level of gag precursor protein, gag pr41, is expressed. Electron microscopy showed that the majority of gag pr41 was budding through the plasma membrane and being released into the culture medium in spherical virus-like particles with a diameter of approximately 100 nm. Metabolic labeling demonstrates that gag pr41 is myristylated. Our results demonstrated that HIV-2 gag pr41 can be assembled into virus-like particles in the absence of other HIV proteins. Rabbits immunized with purified gag pr41 particles produced high-titer antibody and Western blot analysis showed that anti-gag pr41 rabbit sera recognize p17, p24, and p55 gag proteins of HIV-1. These results show that gag pr41 particles are highly immunogenic and that gag proteins of HIV-1 and HIV-2 have similar antigenic epitopes.

Self-binding antibodies (autobodies) form specific complexes in solution

In this report we have shown that members of the murine self-binding antibody family, S107, form soluble complexes and precipitate under conditions in which non-self-binding antibodies remain in solution. Two approaches were used to demonstrate the self-association of autobodies: size-exclusion column chromatography and polyethylene glycol (PEG)-mediated precipitation assay. The anti-phosphorylcholine antibody T15 and two somatic variants, U4, which binds DNA, and U10, which has no identified specificity, produced larger precipitates in 10% PEG than other non-self-binding antibodies. The selectivity of PEG-mediated precipitation of self-binding antibodies is demonstrated by reduction of precipitation with specific haptens known to inhibit self-binding in solid-phase assays. Phosphorylcholine and nucleotides reduced precipitation of T15 and U4, respectively, but not U10. To rule out Fc-Fc mediated self-association in solution, we have also demonstrated self-complexing of F(ab')2 fragments of T15 using PEG. The self-binding locus was further dissected using peptides derived from V regions. A 24-residue peptide derived from the second hypervariable region of the VH of S107 specifically enhanced precipitation of T15, U4, and U10, but not other antibodies. These results provide evidence of a dormant potential of self-binding antibodies to precipitate under conditions that reduce the solubility of proteins. The implication of this potential is discussed with respect to pathological complex formation.

Self-binding antibodies (autobodies) form specific complexes in solution

In this report we have shown that members of the murine self-binding antibody family, S107, form soluble complexes and precipitate under conditions in which non-self-binding antibodies remain in solution. Two approaches were used to demonstrate the self-association of autobodies: size-exclusion column chromatography and polyethylene glycol (PEG)-mediated precipitation assay. The anti-phosphorylcholine antibody T15 and two somatic variants, U4, which binds DNA, and U10, which has no identified specificity, produced larger precipitates in 10% PEG than other non-self-binding antibodies. The selectivity of PEG-mediated precipitation of self-binding antibodies is demonstrated by reduction of precipitation with specific haptens known to inhibit self-binding in solid-phase assays. Phosphorylcholine and nucleotides reduced precipitation of T15 and U4, respectively, but not U10. To rule out Fc-Fc mediated self-association in solution, we have also demonstrated self-complexing of F(ab')2 fragments of T15 using PEG. The self-binding locus was further dissected using peptides derived from V regions. A 24-residue peptide derived from the second hypervariable region of the VH of S107 specifically enhanced precipitation of T15, U4, and U10, but not other antibodies. These results provide evidence of a dormant potential of self-binding antibodies to precipitate under conditions that reduce the solubility of proteins. The implication of this potential is discussed with respect to pathological complex formation.

Mapping of the functional domains of the v-rel oncogene

Previously, the v-rel oncogene was shown to code for a protein of 503 amino acids. The protein product of v-rel was identified as a 59 kDa protein (pp59v-rel), phosphorylated predominantly on serine residues. Although the signal required for the nuclear localization of pp59v-rel in chicken embryo fibroblasts was identified, the regions of v-rel important for transformation have not been mapped. In this study, 12 linker insertion mutants of v-rel were constructed and tested for transforming activity. Seven linker insertion mutants which mapped between amino acid residues 29 and 275 abolished transformation. The remaining 5 mutants which contained linker insertion mutations between amino acid residues 332 and 459 transformed at wild type levels. The results of this analysis localize the functional domains of the v-rel oncogene to the N-terminus. Earlier reports have shown that pp59v-rel resides in a high molecular weight complex with several other cellular proteins. The transforming mutants co-precipitated the same set of cellular proteins when immunoprecipitated with v-rel antiserum. This indicates that all transforming mutants retained the ability to bind within the reported complex.

Tumor idiotype vaccines. VII. Analysis and correlation of structural, idiotypic, and biologic properties of protective and nonprotective Ab2

We have previously generated and used anti-Id mAb (Ab2) to induce protective immunity against the L1210 DBA/2 tumor and for immunotherapy of established tumors. Among various anti-Id that were typed serologically as internal image Ab2 of the mouse mammary tumor virus tumor-associated Ag gp52, only one induced protective immunity and was effective in immunotherapy. In this study we compared the structural, idiotypic, and network properties of the protective and nonprotective antiidiotypic antibodies. The DNA sequence of the variable regions of six anti-Id was determined. The VH sequence of four Ab2, including the protective Ab2, are highly homologous, whereas the VL sequences differ and were assigned to different Vk families. In addition, the DH sequence region of the same four Ab2 are identical, whereas one is highly homologous and another one without homology. Search for amino acid sequence homologies between the Ab2 and gp52 showed the strongest similarities in the CDR2 of the L chain from the protective Ab2. In addition, the CDR2 region also had homology with a T cell epitope on gp52. The biologic basis of effective idiotypic mimicry was studied at the level of Ab3 induced by the Ab2. Id inhibition analysis using Ab3 induced by either protective or nonprotective Ab2, revealed differences. Thus, there is evidence for differences among the Ab1-Ab2-Ab3 cascade induced by protective and nonprotective anti-Id.

Tumor idiotype vaccines. VII. Analysis and correlation of structural, idiotypic, and biologic properties of protective and nonprotective Ab2

We have previously generated and used anti-Id mAb (Ab2) to induce protective immunity against the L1210 DBA/2 tumor and for immunotherapy of established tumors. Among various anti-Id that were typed serologically as internal image Ab2 of the mouse mammary tumor virus tumor-associated Ag gp52, only one induced protective immunity and was effective in immunotherapy. In this study we compared the structural, idiotypic, and network properties of the protective and nonprotective antiidiotypic antibodies. The DNA sequence of the variable regions of six anti-Id was determined. The VH sequence of four Ab2, including the protective Ab2, are highly homologous, whereas the VL sequences differ and were assigned to different Vk families. In addition, the DH sequence region of the same four Ab2 are identical, whereas one is highly homologous and another one without homology. Search for amino acid sequence homologies between the Ab2 and gp52 showed the strongest similarities in the CDR2 of the L chain from the protective Ab2. In addition, the CDR2 region also had homology with a T cell epitope on gp52. The biologic basis of effective idiotypic mimicry was studied at the level of Ab3 induced by the Ab2. Id inhibition analysis using Ab3 induced by either protective or nonprotective Ab2, revealed differences. Thus, there is evidence for differences among the Ab1-Ab2-Ab3 cascade induced by protective and nonprotective anti-Id.

The N-terminal env-derived amino acids of v-rel are required for full transforming activity

Expression of the v-rel oncogene of the reticuloendotheliosis virus, strain T (REV-T), can mediate the transformation of chicken spleen and bone marrow cells. Although the majority of the coding sequence of the v-rel oncogene is derived from the cellular rel sequence, the N- and C-terminal amino acids are coded for by remnants of the REV env gene. The resulting v-rel protein can be described as an env-rel-(out of frame env) fusion protein. Terminal deletion mutants were constructed to determine the role that env sequences play in the transforming activity of v-rel. Deletions were designed to remove only sequences of v-rel derived from former env sequence. Additional deletions removed more substantial amounts of coding sequence. Introduction of deleted genes into an REV-T based retroviral vector permitted the transforming activities to be determined. Deletion analysis indicated that the N-terminal region of pp59v-rel is required for the transforming activity, whereas as many as 100 C-terminal amino acids could be deleted without complete loss of the activity.

Viral RNA and protein synthesis in two LLC-MK2 cell lines persistently infected with human parainfluenza virus 3

Two lines of LLC-MK2 cells persistently infected with human parainfluenza virus 3 (HPIV-3) have been maintained in culture for approximately 3 years. Subgenomic RNAs (putative defective interfering particle genomes) were detected in virions released from both persistently infected cultures. In one of the persistently infected cell lines cyclic variation in the production of virions containing standard virus genomic-size (50S) RNA and subgenomic RNA was observed. The molar ratio of subgenomic RNA to 50S RNA ranged from less than 0.1/1 to 8.7/1. Northern blot analyses revealed that the patterns of viral mRNA synthesis in persistently infected cells from both cultures were similar to those of standard virus infected cells. Furthermore, the intracellular viral-specific proteins had electrophoretic mobilities similar to the corresponding proteins in standard virus-infected cells. Nucleotide sequence analysis of cloned M gene from virus after 29 months of persistence (147 passages) revealed only one variable conservative amino acid change in two clones analyzed from each cell line, indicating that the M protein is not likely to be involved in the maintenance of the persistent infections. The possible mechanisms by which the persistent state is maintained are discussed.

Nucleotide sequence analysis of the L gene of vesicular stomatitis virus (New Jersey serotype): identification of conserved domains in L proteins of nonsegmented negative-strand RNA viruses

We have determined the nucleotide sequence of the L gene of vesicular stomatitis virus (VSV), New Jersey serotype (Ogden strain) by primer extension dideoxy sequencing of the genomic RNA with reverse transcriptase. This analysis completes the entire genomic sequence of the VSVNJ (Ogden). Comparison of the deduced amino acid sequence of this L protein with those reported for L proteins of Indiana serotype and Hazelhurst strain of New Jersey serotype revealed an extensive sequence similarity among all three proteins. The comparison was further extended to the L proteins of other nonsegmented negative-strand RNA viruses, namely the rabies virus and four members of the paramyxovirus family: measles, Newcastle disease, human parainfluenza 3, and Sendai viruses. Our findings confirmed the existence of conserved as well as unique domains in the L proteins, suggesting an evolutionary relationship among these viruses.

Nucleotide sequence analysis of the S genomic segment of Prospect Hill virus: comparison with the prototype Hantavirus

The genomic S RNA segment of Prospect Hill virus (PHV), a member of the Hantavirus genus, was molecularly cloned and the nucleotide sequence of the cDNA determined. The PHV S RNA segment is 1675 nucleotides long. A long open reading frame was identified in the viral complementary-sense RNA that could encode a 433 amino acid (49K) nucleocapsid (N) protein. Comparison with the sequence of the related Hantavirus (Hantaan 76-118) S RNA segment indicated that there was 57% nucleotide sequence homology between the two S RNA segments. A higher degree of conservation in amino acid sequence homology (62%) was observed in the N proteins of these viruses. At the N-terminus 147 of 225 amino acids are homologous, while approximately 82% of the 124 amino acids at the C-terminus are homologous between the two N proteins. The longest stretch of homologous amino acid sequence is found in this region, and is 17 amino acids in length. Also, many of the differences in amino acid sequence between the two N proteins resulted from conservative substitutions. Hydropathy plots of the two N proteins also reveal many similarities including a conserved potential antigenic site. Unlike Hantaan virus, a second smaller overlapping open reading frame was observed in the viral complementary-sense RNA of PHV and could potentially encode a 90 amino acid (10.5K) protein. Our data indicate that the N proteins of PHV and Hantaan virus are closely related despite divergence in the nucleotide sequence of their S RNA segments.

Revised immune network concepts

The idiotype network concept needs to be revised in order to be in agreement with current data on protein/protein interactions, with the phenomenon of T and B cell recognition of idiotopes, and with the failure of certain anti-idiotypes to stimulate a given immune response. It is proposed that the distinction among Ab2 alpha, beta, and gamma is abandoned, as well as the concept of an internal image idiotope which mimics the three-dimensional shape of nominal antigen. In place of these definitions, the concept of "network antigen" is introduced. Network antigens are potentially the entire repertoire of anti-idiotypes. However, their biological effectiveness is controlled and established by two factors: (i) the affinity to the idiotype Ig receptor; and (ii) the preexisting regulatory network segment that controls the outcome of immune stimulation or suppression. Screening for effective idiotype therapeutic agents has to be done with panels of anti-idiotype and idiotype antibodies in order to establish correlations between idiotope expression and disease progression. Recognizing the importance of network segments will be the first step in the direction toward a rational design of idiotype-based therapies.

Glycosylation is not required for the fusion activity of the G protein of vesicular stomatitis virus in insect cells

The gene encoding the complete glycoprotein of vesicular stomatitis virus (VSV, Indiana serotype G protein) with potential asparagine-linked glycans at amino acid residues 179 and 338 was inserted into a baculovirus transfer vector pAcYM1, derived from the nuclear polyhedrosis virus of Autographa californica (AcNPV). The gene was placed under the control of the AcNPV polyhedrin promotor and expressed by the derived recombinant viruses to high levels in Spodoptera frugiperda cell lines. The principal product was the glycosylated version of the G protein, although some alternative (including probable degradation) forms of the protein were also observed. Similar recombinant viruses were prepared with deletion of one, the other, or both glycosylation sites of the VSV G protein. All forms expressed VSV G protein derivatives and mediated cell fusion and the production of syncytia at low pH. The fusogenic properties of the VSV G protein expressed on the surface of insect cells was prevented using anti-VSV sera, or by elevating the pH above 6.2. A reduction of the pH to 5.5, or 5.0, accelerated the rate of syncytia formation.

The 5'-terminal sequence of VSV(NJ) (Ogden): is the interaction of the NS protein with the NS binding site responsible for heterotypic interference activity?

The 5'-terminal sequence of VSV(NJ) (Ogden) and VSV(NJ) (Hazelhurst) was compared in an attempt to understand why the defective interfering particle, DI-LT, heterotypically interferes with VSV(NJ) (Ogden) but not with VSV(NJ) (Hazelhurst). The 5'-terminal sequence of VSV(NJ) (Ogden) genomic RNA was determined by direct RNA sequencing and by DNA sequencing of cDNA clones of the 3'-terminal sequence of VSV(NJ) (Ogden) DI particle genome. Primer extension analysis of the 5'-terminus of VSV(NJ) (Ogden) standard genomic RNA confirmed these data. Within the last 47 nucleotides, equivalent to the negative-strand leader RNA, the only nucleotide changes between VSV(NJ) (Ogden) and VSV(NJ) (Hazelhurst) occur between nucleotides 19 and 26, representing part of the putative NS binding region described by Isaac and Keene (J. Virol. 43, 241-249 (1982] for VSV(IND) DI particles. The spacer (S) region, located between the polyadenylation signal of the L gene and the 47th nucleotide of the leader RNA, contains more differences. The polyadenylation signal of the L gene is fully conserved, but the remainder of the L gene region (177 nucleotides) has highly diverged between VSV(NJ) (Ogden) and VSV(NJ) (Hazelhurst). The changes in the NS binding region of the negative-strand leader RNA provide further evidence for the divergent evolution of VSV(NJ) (Ogden) and VSV(NJ) (Hazelhurst). The NS binding region has been implicated as a crucial site for the initiation of RNA transcription and replication. The interaction of the NS protein with this site may determine the ability of DI particles to interfere heterotypically.

Inhibition of self-binding antibodies (autobodies) by a VH-derived peptide

The self-binding properties of a dominant idiotypic antibody (T15) and a minor idiotypic antibody (M603), both specific for phosphorylcholine, were examined as models of self-binding antibodies (autobodies). Observed differences in the self-binding affinity of T15 and M603 relate to variable sequence differences in their respective heavy and light chains. A molecular recognition theory based on the translation of coding and noncoding DNA strands was used to identify complementary amino acid sequences responsible for self-binding. The second hypervariable region of the heavy chain domain, extending into the third framework region, was predicted as the primary self-binding locus. Among peptides synthesized with different variable heavy and light chain regions, a 24-residue peptide spanning the second hypervariable and third framework regions of the heavy chain of T15 was nearly as effective as phosphorycholine in inhibiting the self-binding complexes.

Neuronal transformations in Alzheimer's disease

Brains of nine early and four advanced Alzheimer patients have been investigated, utilizing three approaches to specify the threshold state of Alzheimer's disease (AD). Extensive thin sectioning electron microscopy (EM) of frontal lobe biopsies, correlated with stringent clinical assessment, has demonstrated that the neuronal cytoskeleton undergoes specific transformations into paired helical filament-like (PHF-like) strands, which lead to the formation of the insoluble paracrystalline paired helical filaments (PHFs). The neurofilamentous network (NFN) transformation plays an important role in this process, whereby segregation, posttranslational modifications and reassembly of the modified components through autocrosslinking, and phase transition occur. According to our data, the threshold state can be defined as the state of irreversible segregation and posttranslational modification of the NFN and the microtubule-associated proteins. At this state, therapeutic intervention to reverse the disease process may be possible. The results indicate similarities between the formation of the paracrystals of the PHFs and the formation of the tropomyosin-like crystals of the Hirano bodies. Close relationships among PHFs and smooth endoplasmic reticulum and plasma membrane do exist. Enveloped virus-like particles have been observed in neurons containing PHFs. A possible role of these virus-like particles as an etiological agent for AD is discussed.

A model for the hapten-induced enhancement of monoclonal antibody binding in ELISA

The unusual binding properties of three anti-phosphocholine (PC) monoclonal antibodies (MAbs) in ELISA has been reported [Hall T. J. (1987) Molec. Immun. 24, 773-777]. These MAbs gave reproducible 2-4 fold increases in binding to PC-protein coated plates in the presence of PC (approximately 2 mM), nitrophenyl PC (approximately 10 micron) and other PC analogues. A model is proposed here in which the complementary and opposite binding of hapten and PC-protein in the combining sites of these MAbs explains the hapten enhanceable binding in ELISA.

Secretion of particles of hepatitis B surface antigen from insect cells using a baculovirus vector

The coding sequences of the hepatitis B virus surface antigen were inserted into a baculovirus transfer vector produced from Autographa californica nuclear polyhedrosis virus (AcNPV) so that the foreign gene was under the control of the AcNPV polyhedrin promoter. Spodoptera frugiperda cells infected with the derived recombinant baculovirus produced and secreted 22 nm particles containing the hepatitis B surface antigen. The particles had morphological and antigenic properties identical to those of 22 nm particles isolated from the plasma of chronic active hepatitis patients.

Defective interfering particles of human parainfluenza virus 3

A cyclic pattern of virus production was observed when human parainfluenza virus 3 (HPIV3) was serially passaged nine times in LLC-MK2 cells. Viruses produced from serial passages 8 and 9 interfered with the replication of standard HPIV3. Three subgenomic RNA species (DI-1, DI-2, and DI-3) and virus genomic RNA were detected in the progeny virions produced from cells mixedly infected with standard virus and virus from either serial passages 5 or 8. Northern blot analysis with probes representing all six HPIV3 structural protein genes revealed that DI-1 and DI-2 RNAs contain sequences from the 5' end of the standard virus genome. DI-1 RNA contains L, HN, and F specific sequences, while DI-2 RNA contains only L and HN sequences. DI-3 RNA did not hybridize with any of the probes used. The possibility that DI-3 RNA contains sequences from the 5' end of the standard virus genome is discussed. These results demonstrate that 5' defective interfering particles are generated during serial passage of HPIV3.

Idiotypic self binding of a dominant germline idiotype (T15). Autobody activity is affected by antibody valency

We have previously described (1-3) an IgM antibody that binds to PC, expresses the T15 idiotype, and binds also to itself or T15 if insolubilized. Because of the simultaneous presence of complementary idiotopes and paratopes this type of antibody has been termed autobody. The self binding involves the antigen-binding site because the F(ab')2 fragment of T15, PC, and no other haptens inhibit the self binding. DNA sequence analysis of 11E7-1 using primer extension cDNA sequencing showed that the variable sequences of H and L chains of 11E7-1 are identical to the germline sequence of the prototype T15 idiotype. Furthermore, monomeric and dimeric T15 IgA were shown to bind to insolubilized T15 and other T15+ antibodies including 11E7-1. Thus, the self-binding activity is an inherent property of the T15 germline sequence. The self binding is highly dependent on the polymeric state of the binding antibody since the IgM pentamer of 11E7-1 is about three fold more effective than the T15 dimer and 50 times more than the T15 monomer. These data suggest that the self-binding activity of a germline-encoded idiotype may play an important role in the biology of its expression, and more specifically, may be responsible for the establishment of its dominant expression.

Nucleotide sequence of the coding and flanking regions of the human parainfluenza virus type 3 fusion glycoprotein gene

The complete nucleotide sequence of the human parainfluenza virus type 3 (HPIV3) fusion (F) protein gene has been determined. The HPIV3 F gene is 1851 nucleotides long including six U residues in the genomic RNA, which probably direct synthesis of the first few nucleotides in the F mRNA polyadenylate tail. The HPIV3 F gene contains a single long open reading frame coding for 539 amino acids. The predicted molecular weight of the unglycosylated precursor F0 protein was 60031. Four potential carbohydrate acceptor sites were identified. Comparison of the HPIV3 F protein sequence with the F gene sequences of two other paramyxoviruses, Sendai virus and simian virus 5, indicated a very close evolutionary relationship between HPIV3 and Sendai virus. Sequence analysis of HPIV3 F gene flanking regions identified signals which appear to be responsible for polymerase recognition and polyadenylation.

Nucleotide sequence of the coding and flanking regions of the human parainfluenza virus 3 hemagglutinin-neuraminidase gene: comparison with other paramyxoviruses

The nucleotide sequence of the human parainfluenza virus 3 (HPIV3) hemagglutinin-neuraminidase (HN) gene has been determined using cDNA clones derived from both HPIV3 genomic RNA and mRNA. The HN mRNA contains 1,882 nucleotides, not including the poly(A) tail. Primer extension experiments were carried out to locate the 5' terminal nucleotide of the HN mRNA. The 3' end of the mRNA was located at a putative polyadenylation signal. The HPIV3 HN mRNA has one large open reading frame that codes for 572 amino acids with a deduced molecular weight of 64,178. Potential polymerase recognition signals for the HN and L genes were located in the flanking regions. The HN protein of HPIV3 shares some common features with the previously sequenced HN proteins of Sendai virus and Simian virus 5. The features include: an N-terminal membrane anchor, two regions of highly conserved amino acid sequence and strong conservation in the positions of the cysteine residues. The relationship is closest between Sendai virus and HPIV3.

Defective interfering particles of VSVNJ (Ogden), generated by heat treatment, contain multiple internal genomic deletions

Defective interfering (DI) particles have been isolated from a heat-resistant strain of the New Jersey (Ogden) serotype of vesicular stomatitis virus (VSV). Most of these DI particles contain various portions of all five cistrons of VSV. The two largest DI particles, NJ-121 and NJ-PG2, represent approximately 60% of the standard virus genome and contain both the positive and negative strand leader RNA templates. These two DI particles are transcriptionally active and synthesize both the positive and negative strand leader RNAs in vitro. Virion RNA probe-mRNA hybridizations and cDNA probe-virion RNA hybridizations have shown that NJ-121 contains mainly sequences from the L and G genes. In contrast, NJ-PG2 has portions of the sequences from all five genes of VSV. Smaller DI particles, NJ-121a, NJ-121b, NJ-PG1, and NJ-JM2 representing approximately 50, 38, 28, and 25% of the standard virus genome respectively, were also generated. These DI particles did not have sequences complementary to the positive strand leader RNA template. The mRNA hybridization patterns and results of the genomic RNAs hybridizing to cDNAs of N, NS, M, and G genes of these DI particles showed that they contain parts of information from all five cistrons. Most of the DI particles appear to be generated by multiple deletions throughout the standard virus genome. None of these DI particles interfered heterotypically with VSVIND-HR in BHK21, R(B77), or L2 cells. However, they interfered well with infection by VSVNJ (Hazelhurst).

Immunoglobulin with complementary paratope and idiotope

A hybridoma antibody (11E7-1) was isolated from a myeloma fusion with nu/nu BALB/c immunized against the T15 idiotype. This IgM antibody exhibited a dual specificity, binding both to PC and to anti-PC antibodies from two idiotype families. Binding to PC and anti-PC antibodies are completely inhibited by PC analogs. Furthermore, the hybridoma antibody binds to itself. Self-binding is also inhibited by PC analogs. From these data, we suggest that 11E7-1 hybridoma antibody has a PC-specific paratope site, and at same time expresses the internal PC antigen idiotope. The term autobody is proposed to signify its self-binding and potential role in autoimmunity. Autobodies may have a unique role in the network of immune system. Furthermore, it may be a model for designing idiotype vaccines.

Identification of the v-rel protein in REV-T transformed chicken bone marrow cells and expression in Cos1 cells

The product of the v-rel oncogene has been identified as a 55,000 dalton protein using antiserum prepared against a synthetic polypeptide whose sequence was deduced from the DNA sequence of v-rel. This antiserum was used in a Western blot assay to identify the product of v-rel in chicken bone marrow cells transformed with reticuloendotheliosis virus, strain T (REV-T), and in Cos1 cells transfected with an expression vector containing the v-rel gene. Transient expression of v-rel under the transcriptional control of the SV40 late promoter in Cos1 cells leads to the synthesis of a rel specific protein with a similar molecular weight.

Analysis of a TH1----TH2 helper cell circuit

In the present study, the T15 idiotype-recognizing T helper cell circuit was dissected with respect to its homeostasis, interactive specificity, stability over time, and effects on B cell expression. Analysis of the TH1 cells by adoptive transfer experiments indicates their short-lived state of activity, during which TH2 cells are stimulated. TH1 cell activity was also directly monitored by the use of TNP-anti-T15 hybridoma antigens. It was found that TH1 cells are detected 1 wk after priming with PC-Hy, whereas TH2 cells become activated after 4 wk of priming. Comparative analysis of TH1 cells by using two different TNP-anti-T15 hybridoma antigens indicates a TH1 specificity for a shared idiotope. The stability over time of the TH1----TH2 circuit was demonstrated by comparing TH2 frequencies in young and old mice. Finally, we addressed the question of the function of the idiotype-recognizing T helper cells and showed that stimulation of T15-idiotype-specific TH2 cells can be correlated with a significant increase in the percentage of T15 idiotype in an anti-PC response. Collectively, these data describe an idiotype-specific T helper circuit as part of the network homeostasis of the immune system.

Analysis of a TH1----TH2 helper cell circuit

In the present study, the T15 idiotype-recognizing T helper cell circuit was dissected with respect to its homeostasis, interactive specificity, stability over time, and effects on B cell expression. Analysis of the TH1 cells by adoptive transfer experiments indicates their short-lived state of activity, during which TH2 cells are stimulated. TH1 cell activity was also directly monitored by the use of TNP-anti-T15 hybridoma antigens. It was found that TH1 cells are detected 1 wk after priming with PC-Hy, whereas TH2 cells become activated after 4 wk of priming. Comparative analysis of TH1 cells by using two different TNP-anti-T15 hybridoma antigens indicates a TH1 specificity for a shared idiotope. The stability over time of the TH1----TH2 circuit was demonstrated by comparing TH2 frequencies in young and old mice. Finally, we addressed the question of the function of the idiotype-recognizing T helper cells and showed that stimulation of T15-idiotype-specific TH2 cells can be correlated with a significant increase in the percentage of T15 idiotype in an anti-PC response. Collectively, these data describe an idiotype-specific T helper circuit as part of the network homeostasis of the immune system.

Frequent generation of new 3'-defective interfering particles of vesicular stomatitis virus

We have isolated and partially characterized a number of different genome types of defective interfering (DI) particles newly generated by a highly heat-resistant strain of vesicular stomatitis virus in either Rat(B77) or Vero cells. Northern blot analyses revealed that many of these DI genomes contain N gene sequences and/or sequences of the NS, M, and G genes. One type contains NS sequences without any indication for the presence of either N, M, or G sequences. Another type of DI particle genomes did not contain any detectable sequences of N, NS, M, or G, but contain panhandle-type sequences and, thus, most likely resembles the 5'-panhandle-type DI particles. Unlike previously assumed, these data demonstrate that DI genomes which have the 3'-terminal N, NS, M, and G genes or portions of these genes conserved do frequently arise together with 5'-DI particle genomes after serial undiluted passages of the heat-resistant strain of vesicular stomatitis virus.

Structural characterization of virion proteins and genomic RNA of human parainfluenza virus 3

The virion proteins and genomic RNA of human parainfluenza virus 3 have been characterized. The virion contains seven major and two minor proteins. Three proteins of 195 X 10(3) molecular weight (195K), 87K, and 67K are associated with the nucleocapsid of the virion and have been designated L, P, and NP, respectively. Three proteins can be labeled with [14C]glucosamine and have molecular weights of 69K, 60K, and 46K. We have designated these proteins as HN, F0, and F1, respectively. HN protein has interchain disulfide bonds, but does not participate in disulfide bonding to form homomultimeric forms. F1 appears to be derived from a complex, F1,2, that has an electrophoretic mobility similar to that of F0 under nonreducing conditions. A protein of 35K is associated with the envelope components of the virion and aggregates under low-salt conditions; this protein has been designated M. The genome of human parainfluenza virus 3 is a linear RNA molecule with a molecular weight of approximately 4.6 X 10(6).

Positive serological evidence that Hantaan virus, the etiologic agent of hemorrhagic fever with renal syndrome, is endemic in Canada

Hemorrhagic fever with renal syndrome is endemic in most parts of the world. The etiological agent in known as Hantaan virus. More than 2000 Canadian sera from all age groups and provinces were tested for the presence of antibody to this virus by the indirect immunofluorescent antibody technique. The frequency of seropositivity ranged from 0.3 to 4.0%, with the national average being 1.4%. Newfoundland and New Brunswick in the Atlantic region had the highest positivity, being higher than hyperendemic areas in Korea. The inland provinces of Ontario, Manitoba, and Alberta had only 0.5% positives to Hantaan virus. In contrast, approximately 1.5% of sera from Saskatchewan, Quebec, and British Columbia were positive. No correlation in positivity was found between geography or sex, but positivity did increase with age. The highest titres were found in the group aged 65 to 93 years.

Assessment of the potential of insecticides, emulsifiers, and solvent mixtures to enhance viral infection in cultured mammalian cells

Various insecticides, solvents, emulsifiers, and mixtures thereof were tested to determine whether these compounds are capable of enhancing the sensitivity of cultured mammalian cells to infection with vesicular stomatitis virus. None of 42 compounds tested significantly enhanced the viral infection.

Reticuloendotheliosis virus-transformed cells contain infectious and noninfectious proviral sequences in different chromosomes

The integration site of reticuloendotheliosis virus proviral DNA in the DNA from a cloned reticuloendotheliosis virus-transformed bone marrow cell line was studied. These reticuloendotheliosis virus-transformed bone marrow cells produce a replication-defective transforming virus (REV-T) and a nontransforming helper virus, designated reticuloendotheliosis-associated virus (REV-At). The DNA from this REV-T transformed bone marrow cell line was hybridized with 3H-labeled in vitro synthesized DNA complementary to the reticuloendotheliosis virus (RE) genome to show that these cells contain approximately five genome equivalents per haploid genome. These hybridization experiments did not distinguish between the transforming and nontransforming virus sequences in these cells. Metaphase chromosomes have been isolated from colcemid-treated bone marrow cells and separated into four different size classes on zonal gradients. Hybridization experiment with RE-specific cDNA indicated that all four size classes of chromosomes contain RE-specific sequences. To locate the infectious provirus DNA of the helper virus REV-At, transfection experiments were performed with DNA extracted from the chromosomes of each size class. Infectious REV-At provirus DNA was found principally in one size class. This size class contained the intermediate size macrochromosomes 5 through 11. These results suggest that REV-At proviral DNA must be integrated into a specific chromosome to produce infectious virus.

Vesicular stomatitis virus can establish persistent infections in Syrian hamsters

Persistent infections by vesicular stomatitis virus (VSV) of the Indiana serotype were readily established in adult Syrian hamsters following intraperitoneal injection of the virus. Plaque-forming virus, identified as VSV by serological and physical criteria, was isolated from brain homogenates of five hamsters that were tested 3 to 8 months after infection. Four of these animals had exhibited either transient or permanent paralysis, whereas the fifth appeared healthy, during the period of observation. At the time of sacrifice all hamsters had high titres of anti-VSV-neutralizing antibodies in their sera.

Mediators of protection against lethal systemic vesicular stomatitis virus infection in hamsters: defective interfering particles, polyinosinate-polycytidylate, and interferon

Homologous defective interfering (DI) particles protected adult Syrian hamsters against lethal systemic infection with vesicular stomatitis virus (VSV) serotype Indiana. The DI particles had to be biologically active, but did not have to be administered at the same inoculation site as the infectious virus. Serum and tissue levels of VSV postinoculation were significantly lower in DI-protected animals than in unprotected controls, suggesting that true autointerference was occurring. However, some aspects of protection also must be mediated through nonspecific mechanisms, since susceptible hamsters could be protected against VSV Indiana by coinjection with heterologous DI particles prepared from VSV serotype New Jersey or by simultaneous administration of polyinosinic acid-polycytidylic acid. By measuring serum levels of putative hamster interferon (type 1), we found that animals coinjected with VSV and DI particles or polyinosinic acid-polycytidylic acid produced significant levels of interferon. Since similarly high serum levels of interferon were measured in recipients of VSV alone (animals that eventually died from infection), there appeared to be no correlation between protection against lethal disease and induced levels of serum interferon. Instead, serum interferon levels correlated positively with amounts of VSV PFU found in serum and tissues of infected animals, the lowest levels being found in serum of animals protected with homologous DI particles. The data are consistent with the hypothesis that autointerference by DI particles as well as various host defense mechanisms (possibly including induction of interferon) participates in protecting hamsters against lethal VSV infection.

Suppression of vesicular stomatitis virus defective intefering particle generation by a function(s) associated with human chromosome 16

Human-mouse somatic cell hybrids were made between adenine phosphoribosyltransferase-deficient mouse L cells and a strain of human primary fibroblasts and selected in medium containing alanosine and adenine (J. A. Tischfield and F. H. Ruddle, Proc. Natl. Acad. Sci. U.S.A. 71:45-49, 1974). These hybrids were tested for the generation of defective interfering (DI) particles of vesicular stomatitis virus to determine whether or not a host gene controls the induction of DI particles. None of the seven independently arising hybrid clones tested generated detectable DI particles during 13 successive undiluted passages. In addition, the parental human cells also failed to generate DI particles. In contrast, the parental mouse cells generated a detectable level of DI particles during continuous passage. Thus, failure to generate DI particles appears to act in a dominant fashion in these hybrids. Human chromosome 16 and adenine phosphoribosyltransferase were present, as a direct consequence of the selection system, in all of the hybrid clones that failed to generate DI particles. It was the only human chromosome observed in the cells of every hybrid clone. This was verified by both isozyme and karyotype analyses. After hybrids were back-selected (with 2,6-diaminopurine) for loss of human adenine phosphoribosyltransferase and chromosome 16, they gained the ability to generate DI particles. Replication of DI particles already present in virus stocks, however, was normal in all of the hybrid clones and the parental human cells. This suggests that the induction, but not the replication, of DI particles is affected by the human genome and that a factor on human chromosome 16 seems to selectively suppress the mouse cell's ability to generate DI particles in the hybrids. These results support the idea that the induction of DI particles is controlled in part by host cell function(s), as suggested previously (C. Y. Kang and R. Allen, J. Virol. 25:202-206, 1978).

Involvement of cells of hematopoietic origin in genetically determined resistance of Syrian hamsters to vesicular stomatitis virus

Susceptibility of Syrian hamsters of the inbred LSH and MHA strains to injection of as few as 10 plaque-forming units of vesicular stomatitis virus (VSV) was shown to occur only after intraperitoneal and intrapleural injection and not after injection of VSV intravenously, intranasally, or in the footpads. Despite the fact that fewer LSH hamsters died when VSV was injected via the latter routes, the histopathology of the VSV-induced disease at early times after infection was identical irrespective of the route of virus administration. Histological examination of tissues at various times after administration of VSV by the various routes revealed that VSV exhibited tropism for lymphoreticular tissue, with the greatest amount of necrosis in the splenic periarteriolar lymphoid sheath. A similar pattern also was observed in VSV-infected tissues from genetically resistant UT1 hamsters. Infectivity titrations of various tissues at different times after intraperitoneal injection of VSV revealed that resistant UT1 hamsters began to clear virus from tissues between 40 and 48 h postinfection, whereas virus titers remained high in susceptible animals. Resistance of UT1 hamsters appeared to require an intact spleen since survival of splenectomized animals was less than that of sham-splenectomized UT1 controls. Sublethal whole-body irradiation was also able to reduce resistance of UT1 hamsters (survival was reduced from 100 to 50%). Bone marrow cells from resistant (UT1 X LSH) F1 females were transferred into lethally irradiated susceptible LSH hamsters, and hematopoietic chimeras were produced. After intraperitoneal injection of 100 plaque-forming units of VSV, all of the female chimeras survived, but only 33% of male chimeras survived. These data indicate that resistance to VSV in Syrian hamsters is mediated, at least partially, by cells of hematopoietic origin.