Zika Virus Tissue and Blood Compartmentalization in Acute Infection of Rhesus Macaques.

Animal models of Zika virus (ZIKV) are needed to better understand tropism and pathogenesis and to test candidate vaccines and therapies to curtail the pandemic. Humans and rhesus macaques possess similar fetal development and placental biology that is not shared between humans and rodents. We inoculated 2 non-pregnant rhesus macaques with a 2015 Brazilian ZIKV strain. Consistent with most human infections, the animals experienced no clinical disease but developed short-lived plasma viremias that cleared as neutralizing antibody developed. In 1 animal, viral RNA (vRNA) could be detected longer in whole blood than in plasma. Despite no major histopathologic changes, many adult tissues contained vRNA 14 days post-infection with highest levels in hemolymphatic tissues. These observations warrant further studies to investigate ZIKV persistence and its potential clinical implications for transmission via blood products or tissue and organ transplants

Biological Effects of Short-Term or Prolonged Administration of 9-[2-(Phosphonomethoxy)Propyl]Adenine (Tenofovir) to Newborn and Infant Rhesus Macaques

The reverse transcriptase inhibitor 9-[2-(phosphonomethoxy)propyl]adenine (PMPA; tenofovir) was previously found to offer strong prophylactic and therapeutic benefits in an infant macaque model of pediatric human immunodeficiency virus (HIV) infection. We now summarize the toxicity and safety of PMPA in these studies. When a range of PMPA doses (4 to 30 mg/kg of body weight administered subcutaneously once daily) was administered to 39 infant macaques for a short period of time (range, 1 day to 12 weeks), no adverse effects on their health or growth were observed; this included a subset of 12 animals which were monitored for more than 2 years. In contrast, daily administration of a high dose of PMPA (30 mg/kg subcutaneously) for prolonged periods of time (>8 to 21 months) to 13 animals resulted in a Fanconi-like syndrome (proximal renal tubular disorder) with glucosuria, aminoaciduria, hypophosphatemia, growth restriction, bone pathology (osteomalacia), and reduced clearance of PMPA. The adverse effects were reversible or were alleviated following either complete withdrawal of PMPA treatment or reduction of the daily regimen from 30 mg/kg to 2.5 to 10 mg/kg subcutaneously. Finally, to evaluate the safety of a prolonged low-dose treatment regimen, two newborn macaques were started on a 10-mg/kg/day subcutaneous regimen; these animals are healthy and have normal bone density and growth after 5 years of daily treatment. In conclusion, our findings suggest that chronic daily administration of a high dose of PMPA results in adverse effects on kidney and bone, while short-term administration of relatively high doses and prolonged low-dose administration are safe

Intraamniotic Zika virus inoculation of pregnant rhesus macaques produces fetal neurologic disease.

Zika virus (ZIKV) infection of pregnant women can cause fetal microcephaly and other neurologic defects. We describe the development of a non-human primate model to better understand fetal pathogenesis. To reliably induce fetal infection at defined times, four pregnant rhesus macaques are inoculated intravenously and intraamniotically with ZIKV at gestational day (GD) 41, 50, 64, or 90, corresponding to first and second trimester of gestation. The GD41-inoculated animal, experiencing fetal death 7 days later, has high virus levels in fetal and placental tissues, implicating ZIKV as cause of death. The other three fetuses are carried to near term and euthanized; while none display gross microcephaly, all show ZIKV RNA in many tissues, especially in the brain, which exhibits calcifications and reduced neural precursor cells. Given that this model consistently recapitulates neurologic defects of human congenital Zika syndrome, it is highly relevant to unravel determinants of fetal neuropathogenesis and to explore interventions

Intraamniotic Zika virus inoculation of pregnant rhesus macaques produces fetal neurologic disease.

Zika virus (ZIKV) infection of pregnant women can cause fetal microcephaly and other neurologic defects. We describe the development of a non-human primate model to better understand fetal pathogenesis. To reliably induce fetal infection at defined times, four pregnant rhesus macaques are inoculated intravenously and intraamniotically with ZIKV at gestational day (GD) 41, 50, 64, or 90, corresponding to first and second trimester of gestation. The GD41-inoculated animal, experiencing fetal death 7 days later, has high virus levels in fetal and placental tissues, implicating ZIKV as cause of death. The other three fetuses are carried to near term and euthanized; while none display gross microcephaly, all show ZIKV RNA in many tissues, especially in the brain, which exhibits calcifications and reduced neural precursor cells. Given that this model consistently recapitulates neurologic defects of human congenital Zika syndrome, it is highly relevant to unravel determinants of fetal neuropathogenesis and to explore interventions

Zika Virus Tissue and Blood Compartmentalization in Acute Infection of Rhesus Macaques

<div><p>Animal models of Zika virus (ZIKV) are needed to better understand tropism and pathogenesis and to test candidate vaccines and therapies to curtail the pandemic. Humans and rhesus macaques possess similar fetal development and placental biology that is not shared between humans and rodents. We inoculated 2 non-pregnant rhesus macaques with a 2015 Brazilian ZIKV strain. Consistent with most human infections, the animals experienced no clinical disease but developed short-lived plasma viremias that cleared as neutralizing antibody developed. In 1 animal, viral RNA (vRNA) could be detected longer in whole blood than in plasma. Despite no major histopathologic changes, many adult tissues contained vRNA 14 days post-infection with highest levels in hemolymphatic tissues. These observations warrant further studies to investigate ZIKV persistence and its potential clinical implications for transmission via blood products or tissue and organ transplants.</p></div

ZIKV infection of 2 adult macaques.

<p>a) Virus inoculation and sampling timeline. Two West Nile virus-antibody negative non-pregnant female macaques received an intravenous inoculation of 5.0 log₁₀ PFU of a 2015 Brazilian ZIKV strain on day 0. Signs of clinical disease were recorded twice daily. Animals were anesthetized daily from 1 to 8 then on 10, 12 and 14 dpi for blood collection and euthanized for tissue collection 14 dpi. Plasma and whole blood ZIKV RNA and infectious virus levels and kinetics b) for animal 5021 and c) for animal 5242. ZIKV RNA levels in plasma (filled circles) and whole blood (filled squares) are reported in mean log₁₀ RNA copies/ml and were assayed in duplicate. Infectious virus levels in plasma (open circles) were measured as Vero cell plaque forming units/ml. Colored bars under the graph show the period plasma tested ZIKV RNA reactive by the Aptima<b>®</b> assay. NT indicates ‘not tested. Dotted line shows limits of detection for both assays 1.6 log₁₀ RNA copies or PFU per ml. d) Neutralizing and binding antibody kinetics and magnitude. ZIKV 80PRNT endpoint antibody titers are reported. The first plasma dilution tested was 1:20. The box shows the ZIKV IgG ELISA test results on plasma tested at a dilution of 1:50; plus and minus signs indicate positive or no reactivity, respectively. e) Saliva ZIKV RNA levels and kinetics. ZIKV RNA levels in saliva eluted from cotton swabs placed in the cheek of macaques, reported in mean log₁₀ RNA copies/ml or gram, were assayed in triplicate with standard deviations noted. The dotted line shows the limit of detection, 2.3 log₁₀ RNA copies/ml or gram.</p

ZIKV tissue distribution in macaques.

<p>ZIKV RNA was measured by qRT-PCR assay in triplicate with standard deviations noted for <b>a)</b> animal 5021 and <b>b)</b> animal 5242. The limit of detection varied depending on the weight of tissue sampled and volume of MEM needed to homogenize to liquefaction, with a mean of 2.3 (range 1.4–4) log₁₀ RNA copies per gram; non-reactive samples are reported at 2.0. log₁₀ RNA copies per gram. Arrows indicate qRT-PCR negative samples that tested positive by the qualitative Aptima<b>®</b> assay. nc indicates not collected.</p