The publication data currently available has been vetted by Vanderbilt faculty, staff, administrators and trainees. The data itself is retrieved directly from NCBI's PubMed and is automatically updated on a weekly basis to ensure accuracy and completeness.
If you have any questions or comments, please contact us.
Respiratory syncytial virus (RSV) is the most common cause of serious lower respiratory tract disease in infants and young children. In this study a hybridoma line secreting a chimpanzee monoclonal antibody that neutralizes RSV was isolated. Two chimpanzees were immunized with recombinant vaccinia viruses that express the RSV F or G surface glycoprotein and 1 month later were infected intranasally with the wild-type RSV strain A2. Peripheral blood lymphocytes obtained from the animals were transformed with Epstein-Barr virus, and lymphoblastoid cell lines that secreted anti-RSV antibodies were identified by an RSV antigen-binding enzyme-linked immunosorbent assay. Supernatants from RSV antibody-secreting lymphoblastoid cell lines were tested for in vitro virus neutralization before being fused to the heteromyeloma cell GLI-H7. A chimpanzee antibody [immunoglobulin G3(lambda) subclass] produced from a hybridoma line designated E1.4/2 was shown to bind to the RSV G glycoprotein and neutralize a panel of subgroup A viruses, but not subgroup B viruses, at low (nanomolar) concentrations. Mice passively immunized with this antibody were partially resistant to RSV strain A2 challenge. The usefulness of such antibodies in immunoprophylaxis and immunotherapy of RSV infection is discussed.
Respiratory syncytial virus (RSV) is the most common cause of viral bronchiolitis and pneumonia in children. The present study compares the level of attenuation, genetic stability and efficacy of three conditional-lethal temperature-sensitive (ts) mutants of the RSV A2 wild-type virus, designated ts-1, ts-1-NG1, and ts-4, in seronegative chimpanzees and also compares their efficacy with that of vaccinia virus recombinants that express the surface glycoproteins of RSV. Each of the ts mutants was highly attenuated in the lower respiratory tract, but still retained the capacity to induce significant rhinorrhoea. Each of the three ts mutants underwent partial reversion to a non-ts (ts+) phenotype during replication in a minority of the chimpanzees. The ts+ virus present in the upper respiratory tract of the chimpanzees did not spread to the lower respiratory tract and represented only a minority fraction of the virus present in the nasopharyngeal swab specimens. The ts mutants were highly immunogenic and provided resistance that effectively restricted RSV replication following virus challenge. In contrast, the vaccinia-RSV recombinants were less immunogenic. They protected the lungs of two of four chimpanzees challenged with RSV, but failed to protect the upper respiratory tract. The chimpanzee can serve as a model for the rapid evaluation of further attenuated live RSV vaccines.
A cold-passaged RSV mutant, designated cp-RSV, which acquired host range mutations during 52 passages at low temperature in bovine tissue culture, was completely attenuated for seropositive adults and children but retained the capacity to cause upper respiratory disease in seronegative infants. We sought to introduce additional attenuating mutations, such as temperature-sensitive (ts) and small-plaque (sp) mutations, into the cp-RSV mutant, which is a ts+ virus, in order to generate a mutant which would be satisfactorily attenuated in seronegative infants and young children. Nine mutants of cp-RSV, which had acquired either the ts or small-plaque sp phenotype, were generated by chemical mutagenesis with 5-fluorouracil. The two ts mutants with the lowest in vitro shut-off temperature, namely the cpts-248 (38 degrees C) and cpts-530 (39 degrees C) mutants, were the most restricted of the nine cp-RSV mutant progeny tested for efficiency of replication in Balb/c mice. In seronegative chimpanzees, the cpts-248 mutant replicated fourfold less efficiently in the nasopharynx and caused significantly less rhinorrhoea than its cp-RSV parent. The cpts-248 mutant virus, like its cp-RSV parent, was 1000-fold restricted in replication in the trachea compared with wild-type RSV. Previously, another candidate RSV live attenuated vaccine strain, a mutant designated ts-1, exhibited some instability of its ts phenotype following replication in susceptible humans or chimpanzees. Hence, we sought cp-RSV ts progeny that exhibited a greater degree of stability of the ts phenotype than the prototype ts-1 mutant.(ABSTRACT TRUNCATED AT 250 WORDS)
RSV and PIV3 are responsible for about 30% of severe viral respiratory tract disease leading to hospitalization of infants and children. For this reason, there is a need to develop vaccines effective against these viruses. Since these viruses cause severe disease in early infancy, vaccines must be effective in the presence of maternal antibody. Currently, several strategies for immunization against these viruses are being explored including peptide vaccines, subunit vaccines, vectored vaccines (e.g., vaccinia-RSV or adenovirus-RSV recombinants), and live attenuated virus vaccines. The current status of these approaches is reviewed. In addition, the immunologic basis for the disease potentiation seen in vaccinees immunized with formalin-inactivated RSV during subsequent RSV infection is reviewed. The efficacy of immunization in the presence of maternal antibody is discussed. Much progress for a RSV and PIV3 vaccine has been made and successful immunization against each of these pathogens should be achieved within this decade.
A cold-passage (cp), temperature-sensitive (ts) RSV mutant designated RSV cpts-248 (shut-off temperature 38 degrees C), which possesses host-range mutations acquired during 52 passages at low temperature in bovine tissue culture and a ts phenotype introduced by subsequent chemical mutagenesis, was found previously to be attenuated, immunogenic, and protective against wild-type challenge in seronegative chimpanzees. We sought to introduce additional attenuating mutations such as small-plaque (sp) and ts mutations into RSV cpts-248 by chemical mutagenesis with 5-fluorouracil with the intent of obtaining cpts-248 derivatives that are more attenuated in mice or chimpanzees and that are more genetically stable following replication in vivo. Ten mutants of RSV cpts-248 which had acquired a sp phenotype or a second ts mutation were generated by chemical mutagenesis. Five cpts-248 derivatives which had acquired mutations that specified a 36 degrees C shut-off temperature for plaque formation and one which had acquired only a sp phenotype were more restricted in replication in Balb/c mice than the cpts-248 parental strain. One mutant, designated RSV cpts-248/404 (shut-off temperature 36 degrees C), was 100 times more restricted in replication in the nasal turbinates of mice and 100 times more restricted in the nasopharynx of seronegative chimpanzees than its cpts-248 parent. The cpts-248/404 mutant was completely restricted in replication in the lower respiratory tract of chimpanzees even following direct intratracheal administration. The ts phenotype of the cpts-248/404 mutant was stable during replication in vivo in mice and chimpanzees.(ABSTRACT TRUNCATED AT 250 WORDS)
We have studied the immunobiology of respiratory syncytial virus (RSV), a major cause of respiratory tract morbidity in children. As part of these studies, it was previously found that immunization of BALB/c (H-2d) mice with a recombinant vaccinia virus (rVV) which encoded the M2 protein of RSV provided complete protection against infection with RSV. This protection was transient and associated with M2-specific CD8+ T-cell (TCD8+) responses. In this study, we used two approaches to demonstrate that expression of an H-2Kd-restricted nonameric peptide (Ser Tyr Ile Gly Ser Ile Asn Asn Ile) corresponding to M2 residues 82 to 90 is necessary and sufficient to induce protective TCD8+ responses. First, infection of mice with an rVV which encoded the peptide M2Met82-90 induced levels of primary pulmonary TCD8+ and resistance to RSV challenge equivalent to that induced by infection with an rVV which expressed the complete M2 protein. Second, elimination of peptide binding to Kd by the replacement of Tyr with Arg at amino acid position 83 of the full-length protein completely abrogated the ability of an rVV-expressing full-length M2 to induce either M2-specific TCD8+ responses or resistance to RSV infection. These findings demonstrate that the M2(82-90) peptide is the sole determinant of immunity induced in BALB/c mice by the M2 protein and that a remarkably high level of transient resistance to infection with pulmonary virus is associated with TCD8+ responses to a single determinant.
The paramyxoviruses respiratory syncytial virus (RSV) and parainfluenza virus type 3 (PIV3) are the two most common agents of severe lower respiratory tract disease in infants and children throughout the world. RSV causes yearly epidemics of bronchiolitis and pneumonia in infants and young children, while PIV3 is a common cause of bronchiolitis, pneumonia and croup. Together these two agents account for up to 30% of all hospitalizations of infants and young children for respiratory tract disease. A licensed vaccine is not currently available for either of these viruses. Development of vaccines against diseases caused by RSV and PIV3 is one of the priorities of the Global Programme for Vaccines (GPV). On 27 March 1994, GPV sponsored a workshop in Nyon, Switzerland, to review the status of vaccine development for these pathogens and to explore new methods of immunization that might be applied to the prevention of diseases caused by RSV and PIV. Furthermore, the World Health Organization (WHO) wished to assess progress in the development of methodologies to rescue infectious virus from cDNA clones of RSV and PIV3. This technology, when developed, will be extremely valuable in developing new vaccine candidates and in unravelling the genetic basis of attenuation of existing vaccines. This paper summarizes the findings presented at this one-day meeting.
In previous studies, a mutant (cp-RSV) of the RSV A2 strain derived from 52 serial cold passages in bovine embryonic tissue culture was highly attenuated in seropositive adults and children but caused upper respiratory tract disease in seronegative infants. We investigated the genetic basis for this attenuation phenotype by comparing the complete genomic RNA sequence of this virus with the published sequence of strain A2 as well as with that of its unattenuated wild-type parent (HEK-7) virus. RNA was extracted from virions grown in tissue culture, reverse transcribed, amplified by the polymerase chain reaction (PCR), cloned, and sequenced. Changes from the published A2 wild-type sequence were confirmed on independently derived cDNA clones and by direct sequencing of PCR fragments. The HEK-7 parent virus was then analyzed at these positions by direct sequencing of PCR fragments. Fifteen nucleotide differences between the published A2 wild-type virus and cp-RSV were found. None appeared to involve cis-acting RNA sequences. Of the 15 nucleotide differences, only 1 occurred outside a translational open reading frame (ORF), and 2 which did occur within ORFs were silent at the amino acid level. The remaining 12 nucleotide differences encoded amino acid changes. All 3 of the mutations which were silent at the amino acid level, and 8 of the 12 which resulted in amino acid differences, were also present in the HEK-7 parent virus and therefore were not changes acquired during the cold passages. Thus, the remaining 4 nucleotide differences and the attendant 4 amino acid changes are associated with the attenuation phenotype of the cp-RSV. Two of the changes occur in the F gene and two in the L gene. These results confirm the previously described RSV genomic sequence, provide the first sequence of a live attenuated RSV vaccine strain, provide the first sequence of an RSV strain which has been evaluated in chimpanzees and humans, and indicate that attenuation in humans of a pneumovirus can be associated with a relatively small number of nucleotide and amino acid changes.
Ts-1, a temperature sensitive (ts) mutant of RSV, was previously derived from RSV A2 virus by mutagenesis with 5-fluorouracil (5-FU). Ts-1 was attenuated for adult volunteers and seropositive children but retained a low level of virulence in seronegative infant vaccinees as indicated by the occurrence of upper respiratory tract disease. Ts-1 NG-1, a more defective derivative of ts-1, was produced by mutagenesis of ts-1 with nitrosoguanidine. However, ts-1 NG-1 still retained a low level of virulence for the upper respiratory tract and showed some genetic instability in chimpanzees. With renewed interest in the goal of developing a live, attenuated RSV vaccine, we have now attempted to further attenuate ts-1 NG-1 by mutagenesis with 5-FU and 5-azacytidine. Four mutants that are phenotypically different from the ts-1 NG-1 parental virus were identified. Each of the four mutants was more restricted in replication in BALB/c mice compared with the ts-1 NG-1 parental virus. One of the ts-1 NG-1 derivatives, termed A-20-4, which showed the lowest (35 degrees C) in vitro shutoff temperature and which was also completely restricted in replication in BALB/c mice, was selected for further evaluation in seronegative chimpanzees. A-20-4 did not cause rhinorrhea in chimpanzees but induced detectable titers of serum RSV neutralizing antibodies in 2 of 4 chimpanzees. Apparent complete protection to subsequent challenge with wild-type RSV was observed in each of the four chimpanzees previously immunized with A-20-4.(ABSTRACT TRUNCATED AT 250 WORDS)
A cold-passaged (cp) temperature-sensitive (ts) RSV mutant, designated RSV cpts-530, which possesses host-range mutations acquired during 52 passages at low temperature in bovine tissue culture and one or more ts mutations induced by chemical mutagenesis (shut-off temperature 39 degrees C) was found previously to be tenfold restricted in its replication in mice as compared to wild-type virus and stable genetically in nude mice. In the current study, we introduced additional attenuating mutations, such as small-plaque (sp) or ts mutations, into cpts-530 by chemical mutagenesis with 5-fluorouracil, with the intent of obtaining derivatives of cpts-530 that were more attenuated in mice or chimpanzees and that were more stable genetically following replication in vivo. Fourteen mutants of RSV cpts-530 which had acquired an additional ts mutation were identified and found to be more restricted in replication in BALB/c mice than the cpts-530 parental strain. One mutant, designated cpts-530/1009 (shut-off temperature 36 degrees C), was 30 times more restricted in replication in the nasal turbinates of mice and threefold more restricted in the nasopharynx of seronegative chimpanzees than its cpts-530 parent. Like its parent, this mutant was highly restricted (30,000-fold) in replication in the lower respiratory tract of chimpanzees even following direct intratracheal inoculation. The cpts-530 and cpts-530/1009 mutants exhibited a high level of stability of the ts phenotype during replication in chimpanzees.(ABSTRACT TRUNCATED AT 250 WORDS)