To examine if cynomolgus macaques previously infected with dengue virus will exhibit antibody dependent enhancement (ADE) or antibody-based protection when infected via mosquito bite with a Zika virus strain PRVABC59. Dengue virus and Zika virus are closely related flaviviruses and in vitro studies have shown cross reactivity between dengue-specific antibodies and Zika virus. This antibody cross-reactivity has shown both protection from Zika virus infection and enhancement of Zika virus infection in independent in vitro studies, but the effects in vivo are not known.
Groups of three or four macaques, each previously infected with one of the four dengue virus serotypes (DENV 1–4), will be infected via mosquito bite with a strain of Zika virus isolated from Puerto Rico (PRVABC59). Blood plasma and serum will be collected from each animal at multiple timepoints before and after infection. Blood plasma will be collected from each animal at 0-10 dpi, 14dpi, 21dpi, and 28dpi. Viral RNA will be measured using qRT-PCR. Blood chemistries, CBCs, neutralizing antibody titers and chemokine/cytokine profiles will be assessed before, during and after Zika virus infection.
Previously challenged with DENV-1
Previously challenged with DENV-2
Previously challenged with DENV-3
Previously challenged with DENV-4
*Group 1, Challenged March 20, 2017
Clinical and Assay Data
Viral RNA Quantification
- Plasma viral load Chart
- Group 1 viral loads Chart
- Group 2 viral loads Chart
- Animals Re-challenged via sub-1 Chart
- Neutralizing Antibody Titers
- March 20, 2017: The first group of seven animals were challenged with ZIKV PR via mosquito feeding. It was difficult to monitor the number of mosquito bites were received by each animal, but it is estimated at an average of four bites per animal. The mosquitoes were exposed to ZIKV infected mice with an average viremia of about 1.4 X10^6 PFU/ml. The second group will be challenged April 18, 2017. All animals will be challenged via mosquito feeding.
- March 24, 2017: Six out of the seven animals are confirmed to be infected. One of the animals, 346817, was confirmed negative 0–4 DPI.
- March 28, 2017: Animal 346817 unexpectedly had a positive plasma viral load eight days post challenge via mosquito feeding. We had discontinued sampling after plasma viral loads came back negative 0–3 DPI. With our previous study ZIKV-023 where we challenged four rhesus macaques via mosquito feeding we only saw a two day delay in 1/4 animals.
- April 18, 2017: The second group of eight animals was challenged via mosquito feeding. Detailed mosquito feeding data can be found here and below.
- April 22, 2017: Six out of the eight animals had a positive plasma viral loads by 4DPI.
- May 17, 2017: Animals 753662 and 941637 appear to have not been infected with ZIKV PR by the mosquitos.
753662 was previously exposed to DENV-3, was fed on by two mosquitoes during ZIKV PR challenge, and had one positive plasma viral load of 149.0 viral RNA copies/ml at 8 days post mosquito challenge. 941637 was previously exposed to DENV-1, was fed on by one mosquito during ZIKV PR challenge, and ZIKV was not detected in plasma 0-10, 14 and 21 days post mosquito challenge.
PRNT assays (using serum from 21 days post challenge) came back negative for animals 753662 and 941637, indicating that they did not seroconvert after the mosquito bite exposure. We are currently planning on challenging these animals with a sub-q injection.
- May24, 2017: Animals 753662 and 941637 will be challenged with ZIKV PR via sub-q injection on May 30, 2017
- The re-challenge with with a subcutaneous injection of 10E4 PFU ZIKV Puerto Rico (PRVABC59) was successful. Both animals had a positive plasma viral load by 1 DPI.