TABLE 1.

Parameters of concentrated virus stocks of different HDV types^f

HDV typee	Total yield		Pre-S1* HDV yield
	GE/μla	%b	GE/μlc	%d
HDV-PLCg	(1.80 ± 0.41) × 105	2.1	(1.72 ± 0.43) × 103	1.0
HDV-Hep3Bh	(1.02 ± 0.06) × 106	11.7	(4.64 ± 0.29) × 103	0.5
HDV-D1i	(1.59 ± 0.46) × 106	18.3	(5.10 ± 1.57) × 105	32.1
HDV-F1j	(8.71 ± 0.85) × 106	100.0	(2.38 ± 0.32) × 106	27.3
HDV-B4i	(9.28 ± 2.18) × 104	1.1	(1.49 ± 0.89) × 104	16.1
HDV-C5i	(4.98 ± 1.93) × 105	5.7	(6.19 ± 2.11) × 104	12.4

^aTotal yield values represent the numbers of HDV genome-containing particles (i.e., the numbers of HDV GE) per microliter of stock for any given type of HDV virion. All virions contained the S protein, while only a fraction of potentially infectious virions contained the molecules of the L protein with the pre-S1 domain exposed on the outer surfaces.

^bThe highest total HDV yield observed for HDV-F1 type was used as the value of 100% for comparison of the efficiency of virion production for the other HDV types.

^cThe pre-S1*-HDV yield values represent the amounts of virions that were immunoprecipitated using the antimatrix antibodies (HDV GE/μl of stock). The antimatrix antibodies displayed strong preferential specificity in binding to the pre-S1 sequences, and the values of pre-S1*-HDV yield serve as a good approximation for the quantification of potentially infectious (L protein-containing) particles. The asterisk indicates that the predominant majority of precipitated particles were pre-S1-HDVs (greater than 80%), and the rest (less than 20%) were apparently L⁻ M⁺ S⁺ virions (see Materials and Methods).

^dThe percentage of pre-S1*-HDVs shows the fraction of pre-S1*-HDVs relative to the total number of secreted virions for any given HDV type.

^eHDV-Hep3B, HDV virions assembled in Hep3B cells; HDV-PLC, HDV virions assembled in PLC/PRF/5 cells. The other HDV virion types were assembled in Huh7 cells using the cotransfection approach described in Materials and Methods. HDV-B4, virions coated with the envelope proteins of HBV genotype B, variant 4; HDV-C5, virions coated with the envelope proteins of HBV genotype C, variant 5; HDV-F1, virions assembled with the envelope proteins of HBV genotype F, variant 1; HDV-D1, virions assembled with the envelope proteins of HBV genotype D, variant 1.

^fThe HDV stocks were concentrated using PEG, as described in Materials and Methods. The data presented here reflect the averages obtained by analysis of several independent preparations of the virus stocks, as indicated in footnotes g to j. To calculate the copy numbers of genomic (G) HDV RNA, the in vitro-transcribed, gel-purified, unit-length G HDV RNA standard was used in the G HDV RNA strand-specific qPCR assay (48). In each qPCR assay, each RNA sample was analyzed in triplicate. The standard errors of the means for both kinds of measurements (total HDV yield and yield of pre-S1*-HDVs) are indicated.

^gSeven independent preparations were used.

^hThree independent preparations were used.

ⁱFour independent preparations were used.

^jTwo independent preparations were used.