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Table 3 Replication and immunogenicity of rDEN1/4 chimeric viruses in rhesus monkeys.

From: Vaccine candidates for dengue virus type 1 (DEN1) generated by replacement of the structural genes of rDEN4 and rDEN4Δ30 with those of DEN1

Virus1 No. of monkeys % of monkeys with viremia Mean no. of viremic days per monkey Mean peak virus titer2 (log10 PFU/ml ± SE) Geometric mean serum neutralizing antibody titer (reciprocal dilution)3 Post-challenge5
      Day 0 Day 28 % sero-conversion4 % of monkeys with viremia Mean peak virus titer2 (log10 PFU/ml ± SE)
DEN1 Puerto Rico/94 4 100 2.8 2.0 ± 0.1 < 5 103 100 0 < 1.0
rDEN1/4 (CME) 4 100 2.0 1.5 ± 0.1 < 5 56 100 0 < 1.0
rDEN1/4Δ30 (CME) 4 50 0.5 1.1 ± 0.1 < 5 < 5 0 75 1.7 ± 0.3
rDEN1/4 (ME) 4 100 4.0 2.1 ± 0.1 < 5 65 100 0 < 1.0
rDEN1/4Δ30 (ME) 6 50 0.7 1.1 ± 0.2 < 5 23 66 0 < 1.0
Mock infected 2 0 0 < 1.0 < 5 < 5 0 100 2.1 ± 0.2
  1. 1 Groups of rhesus monkeys were inoculated subcutaneously on day 0 with 5.0 log10 PFU of the indicated virus in a 1 ml dose. Serum was collected daily for 10 days to detect viremia and on day 28 for determination of neutralizing antibodies.
  2. 2 Virus titer in serum was determined by plaque assay in Vero cells.
  3. 3 Plaque reduction (60%) neutralizing antibody titers were determined using DEN1 Puerto Rico/94 as test virus.
  4. 4 Percentage of monkeys with a four-fold or greater rise in neutralizing antibody levels between day 0 and 28.
  5. 5 Monkeys were challenged after 35 days with DEN1 (Puerto Rico/94) administered subcutaneously in a 1 ml dose containing 5.0 log10 PFU. Serum was collected daily for 10 days to detect viremia.