Susceptibility of channel catfish fry to Channel Catfish Virus (CCV) challenge increases with age

Diseases of Aquatic Organisms

Lora Petrie-Hanson¹  Mary R. Rudis¹  Larry A. Hanson¹ 

关键词: Disease susceptibility;    Ictalurus punctatus;    Teleost;    Ictalurid herpesvirus;    Herpesvirus latency;    Herpesvirus vertical transmission;    Maternal antibody;   

DOI  :  10.3354/dao062027

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Susceptibility of channel catfish to Channel Catfish Virus Disease (CCVD) has been generally considered to be inversely related to age. However, in experimental immersion challenges, we found that channel catfish fry, 3 to 8 d post hatch (dph),are most resistant to CCV and susceptibility increases with age. Initial studies involved 2 spawns that had high CCV carrier percentage. To determine if the resistance seen in the fry was related to the CCV carrier status of the parents, we selected 4spawns from CCV negative parents and 2 spawns from CCV positive parents and immersion challenged them at 8, 23, 36 and 60 dph with 0, 2.5 × 10⁴ or 2.5 × 10⁶ plaque forming units (PFU) of CCV l^–1. Survivorsof the low-dose exposed groups were rechallenged at 120 dph with 2.5 × 10⁶ PFU CCV l^–1. Each brood demonstrated increasing susceptibility to CCVD with age and only the fish that were initially exposed at 60 dph developedprotective immunity. Time course assays evaluating tissue levels of virus in channel catfish exposed to CCV at 7, 21 and 42 dph suggested that the resistance was an early event in the infection process. The resistance in fry was most pronounced in fishfrom CCV positive spawns and was correlated to neutralizing antibody titers in the maternal parent in the 8 dph challenge. However, other factors may be involved because all groups displayed the initial resistance and subsequent susceptibility to CCVD.The age effect may be an important influence on the progression of CCVD outbreaks and indicates the need to consider age for experimental challenges. Additionally, we documented the level of vertical transmission of CCV. Fry from the 4 positive spawns hada CCV prevalence of 40 to 75%.

【 授权许可】

Unknown