Sj. Feng et Ptk. Woo, THERAPEUTIC AND PROPHYLACTIC EFFECTS OF A PROTECTIVE MONOCLONAL-ANTIBODY (MAB-001) AGAINST THE PATHOGENIC HEMOFLAGELLATE CRYPTOBIA SALMOSITIC, Diseases of aquatic organisms, 28(3), 1997, pp. 211-219
We recently produced a species-specific monoclonal antibody (MAb-001)
against a surface antigen of Cryptobia salmositica Katz 1951. When a s
ingle dose (4 % body of weight in mi) of MAb-001 was injected into fis
h infected with C. salmositica, subsequent parasitaemias were signific
antly (p < 0.05) reduced at 48 h after treatment. Parasitaemias were s
till significantly lower than in control fish (injected with cold-bloo
ded vertebrate Ringer's solution, CBVR) 1 wk after injection of MAb-00
1. There was no significant difference in parasitaemias between inject
ion of a single dose or a double dose of MAb-001. Injection of MAb-001
into fish before infection and at 1 wk after infection did not preven
t infection. Parasitaemias in fish which received MAb on Days 0, 1, 2,
3, 4, 5, 6 (daily injected fish) were significantly higher than in fi
sh which received CBVR. The production of complement-fixing antibody a
gainst C. salmositica in MAb daily injected fish was significantly low
er than in those injected with CBVR. Antibodies against MAb-001 were d
etected in fish injected daily with MAb-001. These results suggest tha
t a single dose of MAb-001 is therapeutic and perhaps can be used to p
revent mortality of infected fish. Injection of MAb-001 every day in t
he first week after infection induced significant antigenic competitio
n between parasites and MAb-001. Consequently, these fish produced les
s complement-fixing antibody against C. salmositica and this resulted
in higher parasitaemias than in CBVR-injected fish.