Table 1.
Comparison Between Monoinfection and Coinfection With Severe Acute Respiratory Syndrome Coronavirus 2 and A(H1N1)pdm09 in a Hamster Modela
| Characteristic | SARS-CoV-2 (10 PFUs) | pH1N1 (104 PFUs) | SARS-CoV-2 + pH1N1 | SARS-CoV-2 || pH1N1 | pH1N1 || SARS-CoV-2 |
|---|---|---|---|---|---|
| Overall severity | |||||
| Clinical score, mean ± SDb | 0.00 ± 0.00 | 0.00 ± 0.00 | 1.00 ± 0.00 | 1.00 ± 0.00 | 1.00 ± 0.00 |
| Body weight change, %, mean ± SDc | –5.77 ± 1.96 | 4.87 ± 0.71 | –9.57 ± 1.96 | –11.93 ± 1.08 | –10.43 ± 2.54 |
| Lung histology score | 7.60 ± 0.29 | 4.00 ± 0.58 | 10.67 ± 0.67** | 11.67 ± 0.58** | 10.00 ± 1.0** |
| Nasal turbinate virus replication | |||||
| SARS-CoV-2 gene copy, log copies/1 × 104 β-actin, mean ± SD | 5.48 ± 0.18 | … | 5.61 ± 0.08 | 5.25 ± 0.23 | 5.45 ± 0.32 |
| SARS-CoV-2 plaque, log PFU/mL, mean ± SD | 5.00 ± 0.06 | … | 5.14 ± 0.04 | 4.71 ± 0.35 | 5.70 ± 0.08***/### |
| pH1N1 gene copy, log copies/1 × 104 β-actin, mean ± SD | … | 3.17 ± 0.76 | 2.24 ± 0.38 | 1.56 ± 1.36 | 4.06 ± 0.80 |
| pH1N1 plaque, log PFU/mL, mean ± SD | … | 3.46 ± 0.75 | 3.25 ± 0.78 | 3.6 ± 0.76 | 4.43 ± 0.53 |
| Lung virus replication | |||||
| SARS-CoV-2 gene copy, log copies/1 × 104 β-actin, mean ± SD | 4.62 ± 0.11 | … | 3.55 ± 0.20** | 4.71 ± 0.10### | 2.41 ± 0.67** |
| SARS-CoV-2 plaque, log PFU/mL, mean ± SD | 5.36 ± 0.03 | … | 4.19 ± 0.29*** | 5.74 ± 0.03***/### | 3.65 ± 0.64*** |
| pH1N1 gene copy, log copies/1 × 104 β-actin, mean ± SD | … | 2.61 ± 0.73 | 3.82 ± 0.16 | 2.23 ± 0.83 | 4.32 ± 0.09 ***/### |
| pH1N1 plaque, log PFU/mL, mean ± SD | … | 3.98 ± 0.54 | 3.41 ± 0.77 | 4.36 ± 0.54 | 4.48 ± 0.07 |
| Lung antigen expressiond | |||||
| SARS-CoV-2 nucleocapsid protein | ++ | … | ++ | +++ | + |
| pH1N1 nucleoprotein | … | + | + | + | + |
| Serum neutralizing antibody | |||||
| SARS-CoV-2 neutralizing titer at 7 dpi, mean ± SD | 160.0 ± 0.0 | <5 | 33.3 ± 11.6*** | ND | ND |
| SARS-CoV-2 neutralizing titer at 14 dpi, mean ± SD | 133.3 ± 46.2 | <5 | 120.0 ± 69.3 | ND | ND |
| pH1N1 neutralizing titer at 7 dpi, mean ± SD | <5 | 186.7 ± 122.2 | 120.0 ± 69.3 | ND | ND |
| pH1N1 neutralizing titer at 14 dpi, mean ± SD | <5 | 133.3 ± 46.2 | 93.3 ± 61.1 | ND | ND |
Abbreviations: dpi, days postinfection; ND, not determined; PFU, plaque-forming units; pH1N1, mouse-adapted A/Hongkong/415742/2009 H1N1; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SD, standard deviation.
aAll data represent 4 dpi unless otherwise indicated; || indicates sequential inoculation (24 hours apart).
bA score of 1 was given to each of the following clinical signs: lethargy, ruffled fur, hunchback posture, and rapid breathing.
cBody weight at 4 dpi minus 0 dpi body weight.
d+, a few antigen expressing cells; ++, patches of antigen expressing cell; +++, abundant antigen expressing cells diffuse distribution.
**P < .01, ***P < .001 when compared to monoinfection of SARS-CoV-2 and pH1N1.
### P < .001 when compared to SARS-CoV-2/pH1N1 coinfection.