Pre-exposure to infectious hypodermal and haematopoietic necrosis virus or to inactivated white spot syndrome virus (WSSV) confers protection against WSSV in Penaeus vannamei (Boone) post-larvae.
Larvae and post-larvae of Penaeus vannamei (Boone) were submitted to primary challenge with infectious hypodermal and haematopoietic necrosis virus (IHHNV) or formalin-inactivated white spot syndrome virus (WSSV). Survival rate and viral load were evaluated after secondary per os challenge with WSSV at post-larval stage 45 (PL45). Only shrimp treated with inactivated WSSV at PL35 or with IHHNV infection at nauplius 5, zoea 1 and PL22 were alive (4.7% and 4%, respectively) at 10 days post-infection (p.i.). Moreover, at 9 days p.i. there was 100% mortality in all remaining treatments, while there was 94% mortality in shrimp treated with inactivated WSSV at PL35 and 95% mortality in shrimp previously treated with IHHNV at N5, Z1 and PL22. Based on viral genome copy quantification by real-time PCR, surviving shrimp previously challenged with IHHNV at PL22 contained the lowest load of WSSV (0-1x10(3) copies microg-1 of DNA). In addition, surviving shrimp previously exposed to inactivated WSSV at PL35 also contained few WSSV (0-2x10(3) copies microg-1 of DNA). Consequently, pre-exposure to either IHHNV or inactivated WSSV resulted in slower WSSV replication and delayed mortality. This evidence suggests a protective role of IHHNV as an interfering virus, while protection obtained by inactivated WSSV might result from non-specific antiviral immune response.
Melena
J
J
Fundación CENAIM-ESPOL, Guayaquil, Ecuador.
Bayot
B
B
Betancourt
I
I
Amano
Y
Y
Panchana
F
F
Alday
V
V
Calderón
J
J
Stern
S
S
Roch
Ph
P
Bonami
J-R
JR
D000818:Animals; D017756:Aquaculture; D019223:Densovirinae / Q000276:immunology*; D007814:Larva / Q000821:virology; D033561:Penaeidae / Q000276:immunology / Q000821:virology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D016019:Survival Analysis; D013997:Time Factors; D019562:Viral Load / Q000662:veterinary; D038301:Virus Inactivation; D046848:White spot syndrome virus 1 / Q000276:immunology*