Business Potential for Agricultural Biotechnology - Asian Productivity ...

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Trends in Korean Animal Biotechnology
2003). The EPO protein has three N-glycosylation sites and one O-glycosylation site. N-glycosylation
is considered the key player in the glycoprotein’s activity (Jelkmann, 1992). Not only
the number but also the pattern of glycosylation seems important to the stability and activity of
the protein. For example, instead of the normal three, Amgen’s new EPO product has five Nglycosylations
to increase the half-life of the protein (Egrie and Browne, 2001).
Table 1. World’s Top Biopharmaceutical Products (1996)
Rank Product Company Business 1996 sales
(USD
1,000)
1 Epogen Amgen Amgen 1,150
2 Neupogen Amgen Amgen 1,017
3 Procrit Amgen Ortho Biotech 995
4 Humulin Genentech Eli Lilly 884
5 Engerix-B Genentech SmithKline Beecham 568
6 Intron A Biogen Schering-Plough 524
7 Betaseron Chiron/Berlex Berlex/Schering AG 353
8 Epivir BioChem Pharma/Glaxo Glaxo Wellcome
Wellcome
306
9 Activase Genentech Genentech 284
10 Humatrope Genentech/Eli Lilly Eli Lilly 268
Total 6,348
NLRI researchers have microinjected cloned transgene constructs into a one-celled embryo
which was then transferred to a surrogate sow. The resulting piglets were identified by PCR
using genomic DNA from each piglet’s tail. In 1998, a transgenic founder was identified out of
47 candidate piglets using PCR and Southern blot analysis, both of which showed positive results
for the founder individual. The founder was later named “Saerome,” meaning “novel one”
in Korean. Transformation efficiency—the percentage of successful transgenic—was about 2%
within progeny. The rate was lower, below 0.5%, if one success out of 204 transferred embryos
was considered. Since 1999, a transgenic pig herd has been propagated. The gene transfer rate of
the transgene reached 70% at F2 generation, as seen in Table 2.
Table 2. Transfer Rate of the Transgene in Generations F1 through F3
of a Transgenic Pig Herd
Founder F1 F2 F3
Number of transgenic individuals 1 82 30 34
Gene transfer rate (%) 2.13 17.98 70.18 56.67
The transgene now seems to have stabilized and is being inherited stably by the next generation.
The sex ratio of progeny is about one to one, which suggests that the expression of the
transgene does not inhibit survival of specific sexes during development. The milk from the
transgenic female was examined. In this case study, one sow was milked after delivery for 50
days during the lactation period, and about 880 units of human EPO were found in one milliliter
of pig’s milk, about 8.8 grams per liter. The molecular weight for the EPO was about 34 kDa,
similar to that of natural human EPO. The usual molecular weight of commonly used recombinant
human EPO is about 50 kDa, which is a larger than natural EPO. After removal of glycosylation,
this EPO showed the same molecular weight as commercial EPO that is identical to