Biomedical subjects

B R Murphy

Publications and source records attributed to B R Murphy.

At least 109 records · Page 6Linked to original sources

PubMed1993

The complete nucleotide sequence of two cold-adapted, temperature-sensitive attenuated mutant vaccine viruses (cp12 and cp45) derived from the JS strain of human parainfluenza virus type 3 (PIV3).

Two cold-passaged mutant vaccine viruses (cp12 and cp45) derived from the JS wild-type (wt) strain of human parainfluenza virus type 3 (PIV3) have been sequenced. These mutant viruses display the cold-adapted (ca), temperature-sensitive (ts), and attenuation (att) phenotypes. Sequence data indicate that both cp12 and cp45 sustained nucleotide substitutions during cold passage and subsequent cloning. Fifteen nucleotide changes were present in cp12 and 18 in cp45. Of these changes, some were present in the sequence of the prototype wt strain (Wash/47885/57) or were non-coding changes present in the open reading frames (ORFs). These were considered unlikely to be of significance in contributing to phenotypic differences between the mutants and the JS wt. There were nine remaining changes in cp12 and eight in cp45 that would most likely contribute to their phenotypes. For cp12, two were non-coding changes in regulatory regions, one in the 3' genome leader and one in the NP gene transcription start signal. The remaining seven changes resulted in amino acid substitutions in NP, F, HN, and L. For cp45, two mutations were in a non-coding regulatory region, the 3' genome leader. The remaining six changes resulted in amino acid substitutions in F, HN, and L. Only one amino acid substitution was conserved between cp12 and cp45 (a valine to alanine change at position 384 of the HN gene). These results should prove useful in the future in understanding the genetic basis of attenuation of the cold-passaged PIV3 candidate vaccine viruses.

Adaptation, Physiological↗

PubMed1993

A comparison in chimpanzees of the immunogenicity and efficacy of live attenuated respiratory syncytial virus (RSV) temperature-sensitive mutant vaccines and vaccinia virus recombinants that express the surface glycoproteins of RSV.

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.

Animals↗

PubMed1993

Respiratory syncytial virus-specific immunoglobulins in preterm infants.

Incomplete transfer of maternal antibodies specific to respiratory syncytial virus (RSV) has been suggested as an explanation for the increased risk of RSV infections in preterm infants. Antibodies directed against the two major RSV envelope glycoproteins, F and G, are protective in vitro and in vivo. Our study was conducted to measure IgG, IgG1, IgG2, and IgG3 antibody titers against the RSV F and G glycoproteins in cord sera from infants born at different gestational ages. Titers of neutralizing antibody were measured in a subset of the subjects. The mean (+/- SEM) log2 titers of IgG antibodies directed against the RSV F and G glycoproteins were significantly lower in infants born at < or = 28 weeks of gestation (11.2 and 10.8 for F and G glycoproteins, respectively) than in term infants (12.6 and 12.8 for F and G, respectively) (p < 0.05). Preterm infants born at > or = 29 weeks had titers of antibodies against the F glycoprotein comparable to those of term infants. The highest titers of RSV-specific antibodies were in the IgG1 and IgG2 subclasses. Mean (+/- SEM) neutralizing antibody titers were lower in infants born at < or = 28 weeks (7.7 +/- 0.4) than in term infants (10.2 +/- 0.3) (p < 0.001). We conclude that (1) RSV-specific antibody titers were lower than in term infants only in the most premature infants (< or = 28 weeks) and (2) preterm infants born at > or = 29 or > or = 33 weeks of gestation had RSV-specific titers against F and G glycoproteins, respectively, that were comparable to those of term infants. Preterm infants born at < or = 28 weeks could represent a target population for passive immunoprophylaxis.

Antibodies, Viral↗

PubMed1993

A cold-adapted mutant of parainfluenza virus type 3 is attenuated and protective in chimpanzees.

A live attenuated cold-adapted parainfluenza virus type 3 (PIV-3) vaccine is being developed to prevent the serious lower respiratory tract disease caused by this virus in infants and young children. This cold-passaged mutant (cp45) was evaluated in seronegative chimpanzees and found to be highly attenuated in both the upper and lower respiratory tracts compared to its wild-type parent. Animals immunized with cp45 were also highly resistant to wild-type PIV-3 challenge. Stability of the attenuation phenotype was demonstrated by the administration to 2 additional chimpanzees of an isolate of cp45 obtained after 10 days of replication in a chimpanzee. It was attenuated in both the upper and lower respiratory tracts. The cp45 virus present in the respiratory tract secretions of chimpanzees retained the temperature-sensitive (ts) phenotype, but some loss of ts property was observed in the isolates. These results provide a basis on which to proceed to clinical trials in seronegative human infants and children.

Adaptation, Physiological↗

PubMed1993

Effect of heterosubtypic immunity on infection with attenuated influenza A virus vaccines in young children.

Resistance to infection with an influenza A virus conferred by previous infection with an influenza A virus belonging to another subtype is called heterosubtypic immunity. Heterosubtypic immunity is demonstrable in laboratory animals but is believed to be weak in humans. The present study examined whether heterosubtypic immunity from previous influenza virus infection induced resistance to infection with an attenuated influenza A vaccine virus. Two groups of vaccinees consisting of young infants and children who received either influenza A H1N1 or H3N2 attenuated virus were studied. Influenza A H3N2 virus vaccine recipients were classified by their preexisting H1N1 heterosubtypic antibody level induced by prior infection with wild-type virus, and the H1N1 vaccinees were classified by their history of infection with H3N2 vaccine virus. For both groups of vaccinees, the rates of seroconversion and virus shedding and the level of vaccine virus replication were compared in subjects with and without heterosubtypic immunity. In 48 influenza A H3N2 virus and 39 H1N1 virus vaccinees, heterosubtypic immunity had no demonstrable effect on infectivity, immunogenicity, or replication of attenuated vaccine virus. These observations confirm the weak nature of heterosubtypic immunity in humans and suggest that it will not limit the utility of live attenuated influenza A viruses in young infants and children.

Antibodies, Viral↗

PubMed1993

Rescue of an influenza A virus wild-type PB2 gene and a mutant derivative bearing a site-specific temperature-sensitive and attenuating mutation.

Live attenuated influenza A virus vaccines are currently produced by the transfer of attenuating genes from a donor virus to new epidemic variants of influenza A virus, with the selection of reassortant viruses that possess the protective antigens (i.e., the two surface glycoproteins) of the epidemic virus and the attenuating genes from the donor virus. The previously studied attenuated donor viruses were produced by conventional methods such as passage of virus at low temperature or chemical mutagenesis. The present paper describes a new strategy for the generation of a donor virus bearing an attenuating, non-surface-glycoprotein gene. This strategy involves the introduction of attenuating mutations into the cDNA copy of the PB2 polymerase gene by site-directed mutagenesis, transfection of in vitro RNA transcripts of PB2 cDNA, and recovery of the transfected PB2 gene into an infectious virus. An avian-human influenza A virus PB2 single-gene reassortant virus (with an avian influenza A virus PB2 gene) that replicates efficiently in avian tissue but poorly in mammalian cells was used as a helper virus to rescue a transfected synthetic RNA derived from a human influenza A virus PB2 gene. The desired human influenza A virus mutant PB2 transfectant was favored in this situation because the avian influenza A virus PB2 gene restricts viral replication in mammalian cells in culture, the system used for rescue, thereby providing strong selection for the virus bearing the human influenza A virus PB2 gene. We validated the feasibility of this approach by rescuing the PB2 gene of the wild-type influenza A/Ann Arbor/6/60 virus and a mutant derivative that had a single amino acid substitution introduced at position 265 by site-directed mutagenesis. Previously, this amino acid substitution had been shown to specify both a temperature-sensitive (ts) and an attenuation (att) phenotype. The rescued mutant 265 PB2 transfectant virus exhibited the ts and att phenotypes, which confirms that these phenotypes were specified by this single amino acid substitution. The transfectant virus was immunogenic and protected hamsters from subsequent challenge with wild-type virus. The cDNA copy of this influenza A/Ann Arbor/6/60 virus mutant 265 PB2 gene will be used as a substrate for the introduction of additional attenuating mutations by site-directed mutagenesis.

Animals↗

PubMed1993

The cytolytic activity of pulmonary CD8+ lymphocytes, induced by infection with a vaccinia virus recombinant expressing the M2 protein of respiratory syncytial virus (RSV), correlates with resistance to RSV infection in mice.

Previous studies demonstrated that the pulmonary resistance to respiratory syncytial virus (RSV) challenge induced by immunization with a recombinant vaccinia virus expressing the M2 protein of RSV (vac-M2) was significantly greater 9 days after immunization than at 28 days and was mediated predominantly by CD8+ T cells. In this study, we have extended these findings and sought to determine whether the level of CD8+ cytotoxic T-lymphocyte (CTL) activity measured in vitro correlates with the resistance to RSV challenge in vivo. Three lines of evidence documented an association between the presence of pulmonary CTL activity and resistance to RSV challenge. First, vac-M2 immunization induced pulmonary CD8+ CTL activity and pulmonary resistance to RSV infection in BALB/c (H-2d) mice, whereas significant levels of pulmonary CTL activity and resistance to RSV infection were not seen in BALB.K (H-2k) or BALB.B (H-2b) mice. Second, pulmonary CD8+ CTL activity was not induced by infection with other vaccinia virus-RSV recombinants that did not induce resistance to RSV challenge. Third, the peak of pulmonary CTL activity correlated with the peak of resistance to RSV replication (day 6), with little resistance being observed 45 days after immunization. An accelerated clearance of virus was not observed when mice were challenged with RSV 45 days after immunization with vac-M2. The results indicate that resistance to RSV induced by immunization with vac-M2 is mainly mediated by primary pulmonary CTLs and that this resistance decreases to very low levels within 2 months following immunization. The implications for inclusion of CTL epitopes into RSV vaccines are discussed in the context of these observations.

Animals↗

PubMed1993

A single amino acid in the PB2 gene of influenza A virus is a determinant of host range.

The single gene reassortant virus that derives its PB2 gene from the avian influenza A/Mallard/NY/78 virus and remaining genes from the human influenza A/Los Angeles/2/87 virus exhibits a host range restriction (hr) phenotype characterized by efficient replication in avian tissue and failure to produce plaques in mammalian Madin-Darby canine kidney cells. The hr phenotype is associated with restriction of viral replication in the respiratory tract of squirrel monkeys and humans. To identify the genetic basis of the hr phenotype, we isolated four phenotypic hr mutant viruses that acquired the ability to replicate efficiently in mammalian tissue. Segregational analysis indicated that the loss of the hr phenotype was due to a mutation in the PB2 gene itself. The nucleotide sequences of the PB2 gene of each of the four hr mutants revealed that a single amino acid substitution at position 627 (Glu-->Lys) was responsible for the restoration of the ability of the PB2 single gene reassortant to replicate in Madin-Darby canine kidney cells. Interestingly, the amino acid at position 627 in every avian influenza A virus PB2 protein analyzed to date is glutamic acid, and in every human influenza A virus PB2 protein, it is lysine. Thus, the amino acid at residue 627 of PB2 is an important determinant of host range of influenza A viruses.

Amino Acid Sequence↗

PubMed1993

Immunization of mice with vaccinia virus-M2 recombinant induces epitope-specific and cross-reactive Kd-restricted CD8+ cytotoxic T cells.

The M2 protein of respiratory syncytial virus (RSV) is a protective antigen in H-2d, but not H-2b or H-2k mice. None of the other RSV proteins, excluding the surface glycoproteins that induce neutralizing antibodies, is protective in mice bearing these haplotypes. Thus, the M2 protein stands alone as a nonglycoprotein-protective antigen of RSV. The M2 protein is a target for murine Kd-restricted cytotoxic T lymphocytes (CTLs), and the resistance induced by infection with a vaccinia virus-RSV M2 (vac-M2) recombinant is mediated by CD8+ CTLs. Since the nonameric consensus sequence for H-2 Kd-restricted T-cell epitopes and the amino acid sequence of the M2 protein of subgroup A and B strains of RSV are known, the present study sought to identify the specific epitope(s) on the M2 protein recognized by CD8+ CTLs. This was done by examining the ability of four predicted Kd-specific motif peptides present in the M2 amino acid sequence of an RSV subgroup A strain to sensitize target cells for lysis by pulmonary or splenic CTLs obtained from mice infected with RSV or vac-M2. The following observations were made. First, two of the four peptides sensitized target cells for lysis by pulmonary or splenic CTLs induced by infection with either vac-M2 or RSV. Second, one of the two peptides, namely the 82-90 (M2) peptide, sensitized targets at a very low peptide concentration (10(-10) to 10(-12) M). Third, cold-target competition experiments revealed that the predominant CTL population induced by infection with vac-M2 or RSV recognized the 82-90 (M2) peptide, and this CTL population appeared to recognize the 71-79 (M2) peptide in a cross-reactive manner. Fourth, CTL recognition of targets sensitized with either the 71-79 (M2) or the 82-90 (M2) peptide was Kd restricted. Fifth, CTLs induced by infection with RSV subgroup A or B strains recognized the two M2 peptides. The findings suggest that the M2 protein of RSV contains an immunodominant Kd-restricted CTL epitope consisting of amino acid residues 82 to 90 (SYIGSINNI), which are shared by subgroup A and B RSVs.

Alleles↗

PubMed1993

Surgical salvage of chemorefractory germ cell tumors.

PURPOSE: Patients with disseminated germ cell tumors who relapse after salvage chemotherapy, or who progress during cisplatin-based therapy, have chemorefractory disease and a very poor prognosis. A subset of these patients will have chemorefractory but resectable disease. We have therefore evaluated the role of salvage surgery in this patient population. PATIENTS AND METHODS: We performed a retrospective review of all patients with disseminated germ cell tumors who were felt to have chemorefractory disease and underwent salvage surgery from 1977 to 1990 at Indiana University. All patients had elevated serum markers or other signs of progressive carcinoma. A total of 48 patients underwent surgery (33 retroperitoneal lymph node dissections [RPLNDs], six thoracotomies, three thoracoabdominal resections, and multiple asynchronous procedures in six patients). RESULTS: Thirty-eight of 48 patients (79%) were rendered grossly free of disease and 29 (60%) obtained a serologic remission. Ten patients (21%) remain continuously disease-free with no postoperative treatment with a median follow-up of 46 months (range, 31 to 89). Six additional patients who relapsed after salvage surgery are currently disease-free with further treatment (four with repeat surgery and two with high-dose chemotherapy and autologous bone marrow transplantation [ABMT]). CONCLUSION: Selected patients with chemorefractory but resectable germ cell tumors have definite potential for cure with salvage surgery.

Adolescent↗

PubMed1993

Human monoclonal antibody Fab fragments cloned from combinatorial libraries: potential usefulness in prevention and/or treatment of major human viral diseases.

Currently, there is increased interest in the use of human viral antibodies for prophylaxis and therapy because recent advances in molecular immunology have made it possible to generate large numbers of human monoclonal antibodies of desired specificity and functional activity in short order. The strategy, developed particularly at The Scripps Research Institute and at Cambridge University is based on antigen selection of such antibodies from combinatorial libraries that express Fabs on the surface of filamentous DNA bacteriophage. Fabs or their whole immunoglobulin derivatives that exhibit high avidity for the selecting antigen and high neutralizing activity for the corresponding virus have been identified, and many of these human monoclonal antibodies should prove to be useful in prophylaxis or therapy of presently uncontrolled, medically important human viral diseases.

Antibodies, Monoclonal↗

PubMed1992

Human monoclonal Fab fragments derived from a combinatorial library bind to respiratory syncytial virus F glycoprotein and neutralize infectivity.

Respiratory syncytial virus (RSV) is the most important cause, throughout the world, of severe viral lower respiratory tract illness in young children. Antibodies are known to mediate resistance to RSV infection and illness. We have isolated a number of human monoclonal Fab fragments to RSV F glycoprotein from a combinatorial antibody library expressed on the surface of phage. One of these neutralized a wide range of virus isolates, 10 subgroup A and 9 subgroup B isolates, with a titer (60% neutralization) of approximately 0.1-1.0 micrograms/ml. Another Fab neutralized diverse isolates at a concentration somewhat higher. These human Fab fragments show great promise for use in the prophylaxis or therapy of serious RSV lower respiratory tract disease. For intramuscular or intravenous administration, whole antibodies will be required, whereas for aerosol application, F(ab')2 or Fab fragments may suffice.

Amino Acid Sequence↗

PubMed1992

The attenuation phenotype conferred by the M gene of the influenza A/Ann Arbor/6/60 cold-adapted virus (H2N2) on the A/Korea/82 (H3N2) reassortant virus results from a gene constellation effect.

A single gene reassortant (SGR) virus that derived its M gene from the attenuated influenza A/Ann Arbor/6/60 cold-adapted (CA) donor virus and the remaining genes from the A/Korea/82 (H3N2) wild type (WT) virus (designated A/Korea/82 CA M-SGR) was previously shown to be attenuated in mice, hamsters, ferrets, and humans. The attenuation (ATT) phenotype of this SGR virus could result directly from an altered function of the mutant M gene product of the A/Ann Arbor/6/60 CA virus, which differs from the M gene of the A/Ann Arbor/6/60 WT virus at only one amino acid or, indirectly from a gene constellation effect in which ATT results from an inefficient interaction between the products of the M gene of the A/Ann Arbor/6/60 virus and other genes of the A/Korea/82 virus. Several lines of evidence from the present study are consistent with our interpretation that the ATT phenotype of the A/Korea/82 CA M-SGR results from a gene constellation effect. First, the A/Korea/82 CA M-SGR and an A/Korea/82 SGR containing the A/Ann Arbor/6/60 WT M gene were each restricted in replication in the upper and lower respiratory tract of mice compared with the A/Korea/82 WT virus. Second, an A/Udorn/72 CA M-SGR containing the M gene from the A/Ann Arbor/6/60 CA donor virus in a background of other genes derived from the A/Udorn/72 (H3N2) WT virus was not attenuated in the respiratory tract of mice. These data suggest that the change in the amino acid sequence of the M gene product from the A/Ann Arbor/6/60 WT to CA virus is not responsible for the ATT phenotype of the A/Korea/82 CA M-SGR. In addition, evidence of the genetic instability of the A/Korea/82 CA M-SGR is presented, specifically, an extragenic mutation that results in loss of the ATT phenotype. The implications of these findings for the ATT phenotype of the live attenuated reassortant viruses derived from the A/Ann Arbor/6/60 CA donor virus are discussed.

Adaptation, Physiological↗

PubMed1992

The complete nucleotide sequence of the JS strain of human parainfluenza virus type 3: comparison with the Wash/47885/57 prototype strain.

The nucleotide sequence of the JS strain of human parainfluenza virus type 3 (PIV3) was determined from a series of 14 overlapping cDNA clones and was compared to that of the previously sequenced prototype PIV3 strain, Wash/47885/57 (Galinski, 1991). Overall, there were 630 (4%) nucleotide differences between the two viruses. 15462 nucleotides comprised the JS genome in contrast to 15463 which constituted the genome of the prototype virus. This was accounted for by a single nucleotide deletion in the 5' non-coding region of the JS phosphoprotein gene. Four nucleotide substitutions were found in the leader region at the 3' end of the viral genome at positions 24, 28, 42 and 45, whereas no differences were found in the 44 base trailer region. All of the transcription start and stop signals and intergenic sequences were conserved between the two viruses with the exception of the transcription stop signal of the matrix (M) gene where there was a nucleotide transposition between bases 7 and 8. A comparison of all of the nucleotide differences in the 3' and 5' non-coding regions of each gene showed a variability of 9.8% and 10.5%, respectively. The 3' non-coding regions of the nucleocapsid (NP) and M genes were completely conserved in contrast to the polymerase (L) gene in which 25% of the nucleotides were different. Differences were observed in the 5' non-coding regions of each gene and ranged from 5.9% for the hemagglutinin neuraminidase (HN) gene to 14.6% for the M gene. An analysis of the amino acid differences in each open reading frame revealed that of all the genes, the coding region of the M gene was the most highly conserved (1.1% amino acid variability), while the phosphoprotein (P) gene was the most variable (5.8% amino acid variability). As these two viruses are wild type strains, these differences in nucleotide and amino acid sequence are compatible with efficient replication in vivo.

Base Sequence↗

PubMed1992

A general overview of viral vaccine development.

Explore the source record for details and available documents.

Animals↗

PubMed1992

A phase II trial of interferon alpha-2A plus fluorouracil in advanced renal cell carcinoma. A Hoosier Oncology Group study.

In vitro studies have documented the synergistic activity of interferon (IFN) and fluorouracil (5-FU) in human cancer cell lines, and recent clinical trials have demonstrated the efficacy of this combination in metastatic colon cancer. The current study was undertaken to evaluate the combination of IFN alpha-2a plus 5-FU in previously untreated patients with metastatic renal cell carcinoma. From May 1990 through August 1990, 14 patients with metastatic renal cell carcinoma were treated with 5-FU 750 mg/m2/day continuous infusion IV days 1-5, followed by weekly IV infusions of 5-FU 750 mg/m2 beginning on day 12. Patients concurrently received IFN alpha-2a 9 x 10(6) IU subcutaneously 3 times per week beginning on day 1. The median age of patients treated was 57 (range 38-80) with a median Karnofsky performance status of 90 (range 60-100). Sites of metastases included lung only in 6 patients, liver only in 1 patient, 1 patient had bilateral disease at presentation, and the remaining patients had multiple sites of metastases. The median duration of therapy was 2 months. The predominant toxicities seen were stomatitis, nausea, flu-like symptoms and neurotoxicity. The only grade IV toxicity observed was severe vomiting in 1 patient, though 5 patients discontinued therapy within 2 months because of poor subjective response. With a minimum follow-up of 13 months no objective responses were seen. Thirteen of the 14 patients have had progressive disease and 11 have died. The median time to progression was 2 months (range 0.5-6 months) and the median survival was 5 months (range 2-14.5 + months).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Nucleotide sequence changes in the polymerase basic protein 2 gene of temperature-sensitive mutants of influenza A virus.

Influenza A viruses bearing temperature-sensitive (ts) mutations are restricted in replication in the respiratory tract of animals and humans and are therefore attenuated. Nucleotide sequences were determined for the RNA segment coding for the polymerase basic protein 2 (PB2) from a panel of 12 influenza A/Udorn/307/72 (H3N2) ts viruses, previously characterized to have a ts mutation in the PB2 gene. Each of the viruses with a ts mutation in the PB2 gene had a single amino acid change located at position 65, 100, 112, 174, 298, 310, 386, 391, 556, or 658 of the PB2 protein. The sites of the single mutations were scattered throughout the length of the protein and occurred in regions that are highly conserved among the influenza A virus PB2 predicted amino acid sequences. Interestingly, the substitution of aspartic acid for asparagine at position 556 was found to lie within a region that has homology with cap-binding motifs of human and yeast proteins. Taken together, the findings of lesion sites in the A/Udorn/307/72 PB2 gene and the three reported amino acid changes at positions 265, 417, and 512 for A/AA/6/60, A/WSN/33, and A/FPV/Ros/34 ts PB2 genes, respectively, indicate that the PB2 gene can sustain a viable ts mutation at different sites. This information will allow us to construct cloned cDNA copies of the A/Udorn/307/72 PB2 gene mutagenized at specific sites. Different configurations of two or more ts mutations may be incorporated into the cDNA PB2 gene constructs. We have a host-range reassortant virus that should permit rescue of in vitro-produced transcripts of the PB2 gene into infectious virus. The rescue of these mutated PB2 RNA segments into an infectious influenza A virus may lead to the development of live attenuated reassortant virus vaccines that are satisfactorily attenuated, genetically stable, and immunogenic in humans.

Amino Acid Sequence↗

PubMed1992

Cold-passaged human parainfluenza type 3 viruses contain ts and non-ts mutations leading to attenuation in rhesus monkeys.

Cold-passaged (CP) mutants derived from the JS strain of wild type wt parainfluenza type 3 virus (PIV3) are being evaluated as candidate live virus vaccines. The wt virus was serially passaged 45 times at low temperature and mutant clones with the cold-adapted (CA), temperature-sensitive (ts), and attenuation (ATT) phenotypes were selected following passage levels 12, 18 and 45 (cp12, cp18, and cp45). The cp45 virus was more ts than the cp12 or cp18 mutants, although all 3 mutant viruses were clearly attenuated in rhesus monkeys compared to wild type virus. The mean peak titers of the cp12 and cp18 viruses administered by the intratracheal route were at least 6000-fold lower than JSwt in both the upper and lower respiratory tracts. The cp45 virus was not recovered from monkeys administered virus by the i.t. route alone; however, when the cp45 virus was administered by the intranasal route, it replicated in the upper respiratory tract to a level comparable to that of the cp12 and cp18 viruses, but continued to be markedly restricted in the lower respiratory tract. These data indicate that the cp12 and cp18 viruses contain predominantly non-ts attenuating mutations whereas the cp45 mutant has both non-ts and ts attenuating mutations. Each of the CP mutants induced a high level of resistance to wild type virus challenge. Also, the ATT phenotype of the cp12 and cp18 viruses as measured in rhesus monkeys was stable after replication in chimpanzees or humans, respectively, although the ts phenotype was not. Based on its greater level of temperature sensitivity in vitro and its greater degree of attenuation in rhesus monkeys, the cp45 virus appears to be the most promising vaccine candidate for humans.

Animals↗