Table 5.
Summary of SARS-CoV-2 nonhuman primate rechallenge studies.
| Number, species, § gender, age | Virus strain, inoculation route†, (number exposed) | Clinical signs, (dpi)* | Gross and histologic lung pathology#, dpi* euthanized | Viral detection‡, (dpi)* | (Ref) |
|---|---|---|---|---|---|
| 13 RM 4 infection controls 9 rechallenged 6-12 y (Sex ratio not listed) | SARS-CoV-2 USA-WA1/2020 Combined IT, IN Rechallenged 35 dpi* | Primary infection: Mild ↓ appetite and responsiveness Neutralizing antibody titers significantly higher 14 d post challenge than 14 d after initial infection | 2 euthanized 2 dpi post primary infection: Multifocal interstitial pneumonia, consolidation, edema, DAD 2 euthanized 4 d post primary challenge: Viral pneumonia and inflammation diminished | Initial challenge: Nose, BALF (1) Not detected in plasma At necropsy: vRNA in respiratory, lower GI tract, liver, kidney, hilar LN Rechallenge ↓ vRNA than primary challenge: 3/9 BALF (1) 4/9 sgRNA Nose (1) | 10 |
| 7 RM 3 infection controls 4 challenged 28 d after primary infection 3-5 y (Sex ratio not listed) | SARS-CoV-2/ WH-09/ human/ 2020/CHN IT for primary and rechallenge | Primary challenge: 4/7 lost 200-400 g weight 6/7 reduced appetite No fever Rechallenge: Transient increase in temperature, not seen during primary infection | Primary challenge: 1 NHP euthanized 5 dpi and 7 dpi, Mild to moderate interstitial pneumonia, epithelial degeneration, fibrin deposition Rechallenge: 2 NHP euthanized 5 d after rechallenge had no pathology | Primary infection: Nose, Throat, Rectum (3) Rechallenge: No vRNA detected in nose, throat, or rectal swabs | 28 |
| 8 RM 3 M/ 3 F 6-11 y (2 negative controls) | SARS-CoV-2/ WH-09/ human/ 2020/CHN IT | Primary challenge: 1/6 decreased appetite 2/6 experienced 7% to 8% weight loss by 14 dpi Rechallenge: 2/2 No clinical signs | Primary challenge: 2 NHP euthanized 3 dpi and 6 dpi Interstitial pneumonia, DAD #, thrombus in one NHP, began resolving by 5 dpi | Primary challenge: | 101 |
| 3/6 Nose (2-5) | |||||
| 3/6 Throat (1-6) | |||||
| 3/6 Rectum (2-4) | |||||
| Rechallenge: | |||||
| 2/2 No vRNA detected |
§ RM rhesus macaque, F female, M male, † IT intratracheal, IN intranasal, * dpi days post infection, # DAD diffuse alveolar damage, ‡ BALF bronchoalveolar lavage fluid, GI gastrointestinal, LN lymph node, vRNA viral ribonucleic acid, sgRNA subgenomic ribonucleic acid.