Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruc...Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruction of monolayer of cells appeared after seven days post infection （dpi）. Virus titer was different for each strain, TCIDso ranged from 102.7 to 1069, and LDs0 from 1015 to 1075. Five NNV strains named QN 02, QN 05, QN 07, ND 11 and KH 05 had higher virulence than the other three, the first causing 100% mortality in experimental fish 3-5 dpi. NNV KH 05 had the highest antigenic similarity, and it was inactivated completely by 0.2% formalin, 0.002 mol/L binary ethylenimine （BEI） and 0.1% beta-propiolactone. The neutralization antibody titer obtained in fish of groups immunized by BEI 0.002 M and beta-propiolactone 0.1% inactivated virus was four to eight times higher than that of the group treated with the formalin inactivated virus. The antibody titer in fish immunized with beta-propiolactone inactivated virus was more persistent. The efficacy of vaccines developed from beta-propiolactone inactivated virus and aluminium hydroxide （AH） or aluminum phosphate （AP） was observed by intramuscularly immunizing Epinephelusfuscoguttatus size 1.5 cm. Neutralizing antibodies appeared in vaccinated fish on 10th day post-immunization （dpi） at a dilution of 1：16; 1：32 and highest levels were reached on 30-45 dpi, at dilutions of 1：256 and 1：512, after treatment with AH and AP vaccine, respectively. The relative percent of survival （RPS） of vaccine at 30 dpi was highest with challenge doses 0.2-1 × 10^6.8 TCIDs0, the RPS varied from 80%-83.3% in both groups of AH and AP immunization. This result provides the basis for developing a vaccine against NNA disease.展开更多
Abstract Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive ...Abstract Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive at robust generalizations about processes and mechanisms structuring island biotas, it is important to examine under-represented taxa such as snakes for the insights they may offer. We tested for the existence of nestedness and underlying causal mechanisms using snake data collected on islands in the Thousand Island Lake, China. We used the line-transect method to survey snake occupancy and abundance on 20 islands during two breeding seasons in 2009 and 2010. We used the recently developed metric WNODF to estimate nestedness. We used Spearman rank correlations to examine the associations of nestedness and habitat variables （area, isolation, and habitat diversity） as well as life-history traits （body size, clutch size, geographical range size and area requirement） related to species extinction and immigration tendencies. Snake assemblages were significantly nested and were shaped by extinction processes mediated through area effects and habitat nestedness. The nestedness of snake assemblages was not due to passive sampling or selective colonization. From a conservation viewpoint, our results indicate that we should protect both the largest island with the most species-rich community and habitat-rich islands to maximize the number of species preserved .展开更多
文摘Eight strains of nervous necrosis virus （NNV） isolated in Vietnam were used to detect the pathogenicity and immune response in sea bass （SB）. All strains induced cytopathic effect in SB cell line, complete destruction of monolayer of cells appeared after seven days post infection （dpi）. Virus titer was different for each strain, TCIDso ranged from 102.7 to 1069, and LDs0 from 1015 to 1075. Five NNV strains named QN 02, QN 05, QN 07, ND 11 and KH 05 had higher virulence than the other three, the first causing 100% mortality in experimental fish 3-5 dpi. NNV KH 05 had the highest antigenic similarity, and it was inactivated completely by 0.2% formalin, 0.002 mol/L binary ethylenimine （BEI） and 0.1% beta-propiolactone. The neutralization antibody titer obtained in fish of groups immunized by BEI 0.002 M and beta-propiolactone 0.1% inactivated virus was four to eight times higher than that of the group treated with the formalin inactivated virus. The antibody titer in fish immunized with beta-propiolactone inactivated virus was more persistent. The efficacy of vaccines developed from beta-propiolactone inactivated virus and aluminium hydroxide （AH） or aluminum phosphate （AP） was observed by intramuscularly immunizing Epinephelusfuscoguttatus size 1.5 cm. Neutralizing antibodies appeared in vaccinated fish on 10th day post-immunization （dpi） at a dilution of 1：16; 1：32 and highest levels were reached on 30-45 dpi, at dilutions of 1：256 and 1：512, after treatment with AH and AP vaccine, respectively. The relative percent of survival （RPS） of vaccine at 30 dpi was highest with challenge doses 0.2-1 × 10^6.8 TCIDs0, the RPS varied from 80%-83.3% in both groups of AH and AP immunization. This result provides the basis for developing a vaccine against NNA disease.
基金We thank two anonymous reviewers for helpful comments on earlier version of the manuscript. We are grateful to Chunan Forestry Bureau and the Thousand Island Lake National Forest Park for permits necessary to conduct the research. This study was supported by the National Natural Science Foundation of China （Nos. 31100394, 31170397）, the China Postdoctoral Science Foundation （No. 20070411192）, Zhejiang Provincial Postdoctoral Science Foundation, and the Fundamental Research Funds for the Central Universities.
文摘Abstract Nestedness is a pattern frequently reported for faunal assemblages in fragmented systems. Although nestedness has been documented for a wide range of taxa, it is rarely tested in snake assemblages. To arrive at robust generalizations about processes and mechanisms structuring island biotas, it is important to examine under-represented taxa such as snakes for the insights they may offer. We tested for the existence of nestedness and underlying causal mechanisms using snake data collected on islands in the Thousand Island Lake, China. We used the line-transect method to survey snake occupancy and abundance on 20 islands during two breeding seasons in 2009 and 2010. We used the recently developed metric WNODF to estimate nestedness. We used Spearman rank correlations to examine the associations of nestedness and habitat variables （area, isolation, and habitat diversity） as well as life-history traits （body size, clutch size, geographical range size and area requirement） related to species extinction and immigration tendencies. Snake assemblages were significantly nested and were shaped by extinction processes mediated through area effects and habitat nestedness. The nestedness of snake assemblages was not due to passive sampling or selective colonization. From a conservation viewpoint, our results indicate that we should protect both the largest island with the most species-rich community and habitat-rich islands to maximize the number of species preserved .
