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Recombinant chimeric yellow fever-dengue type 2 virus is immunogenic and protective in nonhuman primates.

ABSTRACT: A chimeric yellow fever (YF)-dengue type 2 (dengue-2) virus (ChimeriVax-D2) was constructed using a recombinant cDNA infectious clone of a YF vaccine strain (YF 17D) as a backbone into which we inserted the premembrane (prM) and envelope (E) genes of dengue-2 virus (strain PUO-218 from a case of dengue fever in Bangkok, Thailand). The chimeric virus was recovered from the supernatant of Vero cells transfected with RNA transcripts and amplified once in these cells to yield a titer of 6.3 log(10) PFU/ml. The ChimeriVax-D2 was not neurovirulent for 4-week-old outbred mice inoculated intracerebrally. This virus was evaluated in rhesus monkeys for its safety (induction of viremia) and protective efficacy (induction of anti-dengue-2 neutralizing antibodies and protection against challenge). In one experiment, groups of non-YF-immune monkeys received graded doses of ChimeriVax-D2; a control group received only the vaccine diluents. All monkeys (except the control group) developed a brief viremia and showed no signs of illness. Sixty-two days postimmunization, animals were challenged with 5.0 log(10) focus forming units (FFU) of a wild-type dengue-2 virus. No viremia (<1.7 log(10) FFU/ml) was detected in any vaccinated group, whereas all animals in the placebo control group developed viremia. All vaccinated monkeys developed neutralizing antibodies in a dose-dependent response. In another experiment, viremia and production of neutralizing antibodies were determined in YF-immune monkeys that received either ChimeriVax-D2 or a wild-type dengue-2 virus. Low viremia was detected in ChimeriVax-D2-inoculated monkeys, whereas all dengue-2-immunized animals became viremic. All of these animals were protected against challenge with a wild-type dengue-2 virus, whereas all YF-immune monkeys and nonimmune controls became viremic upon challenge. Genetic stability of ChimeriVax-D2 was assessed by continuous in vitro passage in VeroPM cells. The titer of ChimeriVax-D2, the attenuated phenotype for 4-week-old mice, and the sequence of the inserted prME genes were unchanged after 18 passages in Vero cells. The high replication efficiency, attenuation phenotype in mice and monkeys, immunogenicity and protective efficacy, and genomic stability of ChimeriVax-D2 justify it as a novel vaccine candidate to be evaluated in humans.

SUBMITTER: Guirakhoo F

PROVIDER: S-EPMC112032 | biostudies-literature | 2000 Jun

REPOSITORIES: biostudies-literature

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Recombinant chimeric yellow fever-dengue type 2 virus is immunogenic and protective in nonhuman primates.

Guirakhoo F F Weltzin R R Chambers T J TJ Zhang Z X ZX Soike K K Ratterree M M Arroyo J J Georgakopoulos K K Catalan J J Monath T P TP

Journal of virology 20000601 12

A chimeric yellow fever (YF)-dengue type 2 (dengue-2) virus (ChimeriVax-D2) was constructed using a recombinant cDNA infectious clone of a YF vaccine strain (YF 17D) as a backbone into which we inserted the premembrane (prM) and envelope (E) genes of dengue-2 virus (strain PUO-218 from a case of dengue fever in Bangkok, Thailand). The chimeric virus was recovered from the supernatant of Vero cells transfected with RNA transcripts and amplified once in these cells to yield a titer of 6.3 log(10) ...[more]

PMID: 10823852

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Project description:We previously reported construction of a chimeric yellow fever-dengue type 2 virus (YF/DEN2) and determined its safety and protective efficacy in rhesus monkeys (F. Guirakhoo et al., J. Virol. 74:5477-5485, 2000). In this paper, we describe construction of three additional YF/DEN chimeras using premembrane (prM) and envelope (E) genes of wild-type (WT) clinical isolates: DEN1 (strain PUO359, isolated in 1980 in Thailand), DEN3 (strain PaH881/88, isolated in 1988 in Thailand), and DEN4 (strain 1228, isolated in 1978 in Indonesia). These chimeric viruses (YF/DEN1, YF/DEN3, and YF/DEN4) replicated to ~7.5 log(10) PFU/ml in Vero cells, were not neurovirulent in 3- to 4-week-old ICR mice inoculated by the intracerebral route, and were immunogenic in monkeys. All rhesus monkeys inoculated subcutaneously with one dose of these chimeric viruses (as monovalent or tetravalent formulation) developed viremia with magnitudes similar to that of the YF 17D vaccine strain (YF-VAX) but significantly lower than those of their parent WT viruses. Eight of nine monkeys inoculated with monovalent YF/DEN1 -3, or -4 vaccine and six of six monkeys inoculated with tetravalent YF/DEN1-4 vaccine seroconverted after a single dose. When monkeys were boosted with a tetravalent YF/DEN1-4 dose 6 months later, four of nine monkeys in the monovalent YF/DEN groups developed low levels of viremia, whereas no viremia was detected in any animals previously inoculated with either YF/DEN1-4 vaccine or WT DEN virus. An anamnestic response was observed in all monkeys after the second dose. No statistically significant difference in levels of neutralizing antibodies was observed between YF virus-immune and nonimmune monkeys which received the tetravalent YF/DEN1-4 vaccine or between tetravalent YF/DEN1-4-immune and nonimmune monkeys which received the YF-VAX. However, preimmune monkeys developed either no detectable viremia or a level of viremia lower than that in nonimmune controls. This is the first recombinant tetravalent dengue vaccine successfully evaluated in nonhuman primates.

Project description:Two yellow fever virus (YFV)/dengue virus chimeras which encode the prM and E proteins of either dengue virus serotype 2 (dengue-2 virus) or dengue-4 virus within the genome of the YFV 17D strain (YF5.2iv infectious clone) were constructed and characterized for their properties in cell culture and as experimental vaccines in mice. The prM and E proteins appeared to be properly processed and glycosylated, and in plaque reduction neutralization tests and other assays of antigenic specificity, the E proteins exhibited profiles which resembled those of the homologous dengue virus serotypes. Both chimeric viruses replicated in cell lines of vertebrate and mosquito origin to levels comparable to those of homologous dengue viruses but less efficiently than the YF5.2iv parent. YFV/dengue-4 virus, but not YFV/dengue-2 virus, was neurovirulent for 3-week-old mice by intracerebral inoculation; however, both viruses were attenuated when administered by the intraperitoneal route in mice of that age. Single-dose inoculation of either chimeric virus at a dose of 10(5) PFU by the intraperitoneal route induced detectable levels of neutralizing antibodies against the homologous dengue virus strains. Mice which had been immunized in this manner were fully protected from challenge with homologous neurovirulent dengue viruses by intracerebral inoculation compared to unimmunized mice. Protection was associated with significant increases in geometric mean titers of neutralizing antibody compared to those for unimmunized mice. These data indicate that YFV/dengue virus chimeras elicit antibodies which represent protective memory responses in the mouse model of dengue encephalitis. The levels of neurovirulence and immunogenicity of the chimeric viruses in mice correlate with the degree of adaptation of the dengue virus strain to mice. This study supports ongoing investigations concerning the use of this technology for development of a live attenuated viral vaccine against dengue viruses.

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Recombinant chimeric yellow fever-dengue type 2 virus is immunogenic and protective in nonhuman primates.

Publications

Recombinant chimeric yellow fever-dengue type 2 virus is immunogenic and protective in nonhuman primates.

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