offprint
offprint
l
i
¼ exp
X
L
j¼1
D
ij
!
, (2)
it is obvious that the smaller the Ab-Ab affinity is, the
smaller l
i
is. Generally, before employed in the clonal
operator, l
i
is normalized to the interval [0, 1], and if
D
ij
¼ 0, then l
i
¼ 1. l
i
can be used to adjust the scale of
clones and reduce the possibility of producing closely
related antibodies.
Based on the clonal selection theory and the immune
network mechanism, a new artificial intelligent operator is
proposed. The operator includes a polyclonal operator and
monoclonal operator, which are defined as follows.
5.2 Monoclonal operator
Monoclonal operator is a compositive operator, which
integrates clone, clonal mutation, and clonal selection
together; it can be defined as follows
Clone T
C
c
: I
n
! I
N
c
, namely
A
#
ðkÞ¼T
C
c
ðAðkÞÞ ¼ ½T
C
c
ða
1
ðkÞÞ,T
C
c
ða
2
ðkÞÞ,:::,T
C
c
ða
n
ðkÞÞ
¼ a
1
ðkÞ,:::,a
1
ðkÞ
|fflfflfflfflfflfflfflfflfflffl{zfflfflfflfflfflfflfflfflfflffl}
q
a
1
, a
2
ðkÞ,:::a
2
ðkÞ,
|fflfflfflfflfflfflfflfflfflffl{zfflfflfflfflfflfflfflfflfflffl}
q
a
2
:::, a
n
ðkÞ,:::a
n
ðkÞ
|fflfflfflfflfflfflfflfflffl{zfflfflfflfflfflfflfflfflffl}
q
a
n
2
6
4
3
7
5
¼½A,A
í
1
,A
í
2
,:::,A
í
n
,
(3)
where T
c
c
ða
i
ðkÞÞ ¼ A
í
i
¼ I
i
a
i
ðkÞ, i ¼ 1,2, ,n, and I
i
is q
a
i
– 1 -dimensional row vector and its each element is
1, we call A
í
i
is q
a
i
– 1 clone pool of antibody a
i
, and q
a
i
is
defined as follows
q
a
i
¼ gðN
c
,f ða
i
ðtÞÞ,l
i
Þ: (4)
In this paper, we set
β
i
¼ l
i
f ða
#
ðkÞÞ
X
n
j¼1
f ða
j
ðkÞÞ
: (5)
And, we define q
a
i
as follows
q
a
i
¼ Int N
c
β
i
X
n
j¼1
β
j
0
B
B
B
B
@
1
C
C
C
C
A
, i,j ¼ 1,2, ,n: (6)
N
c
> n is a given value related to the scale of clone, and
Int (x) rounds the argument x toward the smallest integer
greater than x. Obviously, q
a
i
is used to reflect the clonal
scale of antibody a
i
. And N
c
¼
X
n
i¼1
q
a
i
. In fact, Eq. (6)
shows that each antibody will be viewed locally and has a
different clone size from the others, and its clone size
depends on the antigenic affinity f ða
i
ðtÞÞ and l
i
, which is
related to the antibody affinity of a
i
with other antibodies
in the population (as defined in Eq. (2)).
From the description above, it can be seen that q
a
i
is
directly proportional to l
i
and the antigenic affinity, which
means the lower the similarity with other antibodies and
the larger the antigenic affinity of antibody a
i
is, the larger
its clone size is.
Clonal mutation T
C
m
: I
Nc
! I
N
c
. To maintain the
information of the original antibody population, the clonal
mutation does not act on the initial antibodies, A 2 A
#
,
which can be understood as follows, for example, one
clonal pool contains 5 of the same antibodies, and then the
clonal mutation will apply to 4 antibodies in this clonal
pool, and leave one antibody as the parent antibody. The
clonal mutation operation can be defined as follows:
A
$
ðkÞ¼T
C
m
ðA
#
ðkÞÞ: (7)
Moreover, the mutation probability is used as follows:
pða
í
i
! a
î
j
Þ¼p
Hða
í
i
,a
î
j
Þ
m
ð1 – p
m
Þ
L – H ða
í
i
,a
î
j
Þ
, (8)
where H ðx,yÞ is the Hamming distance function.
Clonal selection T
c
s
: I
N
c
! I
n
. For the each clone pool
after clonal mutation, select the antibody with the highest
antigenic affinity, namely, b
i
¼fa
î
ij
ðkÞjmax f ða
î
i
Þ,
j ¼ 1,2, ,q
a
i
– 1g, i ¼ 1,2, ,n, if the antibody a
i
in
the original population satisfies:
f ða
i
Þ < f ðb
i
Þ: (9)
Then b
i
replaces the antibody a
i
in the original
population. Otherwise, keep the antibody a
i
. Fig. 1
shows the monoclonal process of one antibody cloned
for 10 times.
5.3 Polyclonal operator
The main difference between the polyclonal operator and
the monoclonal operator lies in that the polyclonal
operator includes clonal recombination.
Clonal recombination T
c
r
: I
Nc
! I
N
c
. Similar to the
clonal mutation, the clonal recombination is unused to the
original population A, and we adopt the following
540 Front. Comput. Sci. China 2010, 4(4): 536–559
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