| Autor: |
Hedrick, RonaldP., McDowell, TerryS., Mukkatira, Kaveramma, MacConnell, Elizabeth, Petri, Brian |
| Zdroj: |
Journal of Aquatic Animal Health; June 2008, Vol. 20 Issue: 2 p116-125, 10p |
| Abstrakt: |
AbstractThe effects of freezing, drying, ultraviolet irradiation (UV), chlorine, and a quaternary ammonium compound on the infectivity of the myxospore stage of Myxobolus cerebralis(the causative agent of whirling disease) for Tubifex tubifexwere examined in a series of laboratory trials. Freezing at either −20°C or −80°C for a period of 7 d or 2 months eliminated infectivity as assessed by the absence of production of the actinospore stage (triactinomyxons (TAMs)) from T. tubifexcultures inoculated with treated myxospores over a 4–5-month period. Myxospores retained infectivity when held in well water at 5°C or 22°C for 7 d and when held at 4°C or 10°C d for 2 months. In contrast, no TAMs were produced from T. tubifexcultures inoculated with myxospores held at 20°C for 2 months. Drying of myxospores eliminated any evidence of infectivity for T. tubifex. Doses of UV from 40 to 480 mJ/cm2were all effective for inactivating myxospores of M. cerebralis, although a few TAMs were detected in one replicate T. tubifexculture at 240 mJ/cm2and in one replicate culture at 480 mJ/cm2. Treatments of myxospores with chlorine bleach at active concentrations of at least 500 mg/L for 15 min largely inactivated myxospore infectivity for T. tubifex. Likewise, there was no evidence of TAMs produced by T. tubifexinoculated with myxospores treated with alkyl dimethyl benzyl ammonium chloride (ADBAC) at 1,500 mg/L for 10 min. Treatments of myxospores with 1,000-mg/L ADBAC for 10 min reduced TAM production in T. tubifexcultures sevenfold relative to that in cultures inoculated with an equal number of untreated myxospores. These results indicate that myxospores of M. cerebralisdemonstrate a selective rather than broad resistance to selected physical and chemical treatments, and this selective resistance is consistent with conditions that myxospores are likely to experience in nature. |
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