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Table 4 Replication and immunogenicity of DEN-2 viruses in rhesus monkeys

From: Vaccine candidates derived from a novel infectious cDNA clone of an American genotype dengue virus type 2

Virusa % with viremia Mean no. of viremic days per monkeyb Mean peak virus titer (log10PFU/ml ± SE) Geometric mean serum neutralizing antibody titer on day 28 (reciprocal dilution)c Virus replication after challenged
      % with viremia Mean peak virus titer (log10PFU/ml ± SE)
Mock 0 0 <0.7 <10 100 2.1 ± 0.1
DEN-2 Tonga/74 100 4.5 2.1 ± 0.3 311 0 <0.7
rDEN-2 100 4.0 1.9 ± 0.1 173 0 <0.7
rDEN2Δ30 100 2.8 1.7 ± 0.2 91 0 <0.7
  1. a Groups of rhesus monkeys (mock: n = 2; viruses: n = 4) were inoculated subcutaneously with 105 PFU of the indicated virus in a 1 ml dose. Serum was collected daily for day 0 to 6; day 8, 10, 12 and 28
  2. b Virus titer in serum was determined by plaque assay in Vero cells. The lower limit of detection was 0.7 log10PFU/ml. Viremia was not detected in any monkey after day 6.
  3. c Plaque reduction (60%) neutralizing antibody titers were determined using DEN-2 Tonga/74. Limit of detection was < 1:10. All monkeys inoculated with virus had a four-fold or greater increase in neutralizing antibody titer.
  4. d Vaccinated rhesus monkeys were inoculated subcutaneously with 105 PFU of DEN-2 Tonga/74 virus in a 1 ml dose. Serum was collected daily for day 0 to 8.