Freeze-Drying of Plant Tissue Containing HBV Surface Antigen for the Oral Vaccine against Hepatitis B

Table 1

S-HBsAg content in transgenic lettuce leaves after freeze-thawing cycle.

Tissue		S-HBsAg
Treatment		VLPs		Total
Freeze	Thaw	Content; g/g FW	Change; %	Content; g/g FW	Change; %
“Fast”	“Fast”	3.4 ± 1.1	19.2 ± 6.3	39.5 ± 1.5	134.1 ± 5.2
“Fast”	“Slow”	2.9 ± 1.1	16.5 ± 5.9	40.0 ± 1.2	135.8 ± 4.0
“Slow”	“Fast”	7.0 ± 1.4	39.5 ± 8.0	33.0 ± 2.0	112.0 ± 6.8
“Slow”	“Slow”	6.3 ± 1.7	35.8 ± 9.6	35.6 ± 3.4	120.9 ± 11.7
Untreated		17.7 ± 1.6	100.0 ± 8.9	29.5 ± 1.3	100.0 ± 4.5

Material treatment: a/freezing: “fast”—liquid nitrogen quenching, “slow”—cooling at 2°C/min; b/thawing: “fast”—immersing in 4°C water, “slow”—placing in 4°C air. Percentage values represent drop of S-HBsAg compared to untreated reference sample.