Table 2

Potential or in-use quantification methods for influenza virus-like particles
Quantification method Used with flu-VLPs Sample type LOD LOQ Working Range SD (%RSD) Assay Duration Ref
HA antigen SRID Yes P, NP, ~3 μg/ml ~3 μg/ml 3.12 – 100 ug/ml (10%) ~30 h [36]
HA assay Yes P, NP 2 HA unit/50ul 2 HA unit/50ul 2 - 2048 HA units/50 μl ~0,066 % ~5 h [37,38]
LC-MS No P 25 fmol 25 fmol 25 - 400fmol/10ul (H1): 1.14 (3.5%) n.s. [39,40]
(H3): 1.24 (5.6%)
(B): 5.04 (9.7%)
RP-HPLC Yes V (H1): 0.25 ug/ml (H1): 0.75ug/ml 2.5-100ug/ml 3.58 % 10-20 min [41]
(B): 1 ug/ml (B): 3ug/ml 7.73%
Universal ELISA No V 1ug/ml 0.2-16ug/ml 0.14-0.3 (14 - 30%) n.s. [42]
SPR immuno assays No P, NP, V <0.5ug/ml 1ug/ml 1-15ug/ml n.s. n.s. [43]
NA antigen TBA NA assay Yes P 0.34 mU/ml 1.03 mU/ml 0.54 -6.47 mU/ml 2.95% n.s. [35]
NA star assay Yes P, NP 3 pM 3pM 3-10.5nM n.s. ~1.5 h [44]
Amplex Red NA assay Yes P 2.09 mU/ml 6.32mU/ml 2.00-7.00 mU/ml 16% [35]
NA-Fluor Assay Yes P, NP 0.09 mU/ml 0.17-2.00 mU/ml n.s. 2.55% ~4 h [35]
HA & NA antigen LC-MS No V n.s. n.s. NA: 2-12ug/ml n.s. ~5 h [39]
HA: 10-70ug/ml
Universal SlotBlot No V, rHA, rNA 0.032 ug/ml 0.032 ug/ml HA: 0.032-3ug/ml 2300 - 13500 (5%) particles/count n.s. [14,45]
NA: 0.037-10 ug/ml
Total particles DLS No P, NP 8.6 × 101 TCI50units/ml 8.6 × 101 TCI50units/ml 8.6 × 101 to 3.4 × 104 TCID50units/ml n.s. <30min [46]
Virus Counter No P, NP (NP): 3.6 × 106 VP/ml (NP): 3.6 × 106 VP/ml 105 - 109 VP/ml 0.09 +/− 0.03 VP/ml ~40 min [47]
(P): 1.0 × 105 VP/ml (P): 1.0 × 105 VP/ml
AFFFF-MALS No P, NP n.s. n.s. 5 × 108 - 4.5 × 109 VP/ml n.s. ~1 h [48-50]

Type of samples: P, Purified; NP, Non-purified; V, Vaccine doses; N.s, Non specified.

Thompson et al.

Thompson et al. Virology Journal 2013 10:141   doi:10.1186/1743-422X-10-141

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