Table 4

Culture of on Vero cell lines from dust sample homogenates collected inside a cave, Bizkaia, Spain, March 2021–February 2023 (n = 9)

Sampling date Inoculated amount (GE/mL) Culture on Vero E6 cell lines (GE/mL)
Day 6 p.i. Passage 1 Passage 2 Passage 3 Viable
Mar 2021 3.68 × 104 7.39 × 104 4.27 × 105 5.17 × 105 2.63 × 106 Yes
May 2021 3.56 × 104 8.56 × 103 Contaminated Not performed
Aug 2021 4.67 × 107 8.17 × 107 1.31 × 108 1.29 × 108 4.76 × 107 Yes
Nov 2021 2.43 × 107 2.54 × 107 5.73 × 107 5.05 × 107 9.09 × 107 Yes
Feb 2022 3.96 × 106 4.91 × 106 1.35 × 107 1.27 × 107 1.94 × 107 Yes
May 2022 4.88 × 105 8.24 × 105 1.82 × 106 2.98 × 106 4.71 × 106 Yes
Sep 2022 1.78 × 106 2.46 × 106 2.94 × 106 8.59 × 105 1.27 × 106 No
Dec 2022 5.33 × 105 1.61 × 106 1.04 × 106 1.15 × 106 0 Yes
Feb 2023 6.47 × 105 8.65 × 105 2.04 × 105 3.45 × 105 0 No

GE: genome equivalents of determined by quantitative real-time PCR targeting the gene; p.i.: post-inoculation.