Detection of ‘long-haired’ Saprolegnia (S. parasitica) isolates using monoclonal antibodies

P. 726-733The ability of five monoclonal antibodies (Mabs) raised against a pathogenic Saprolegnia parasitica isolate from brown trout to detect and differentiate between isolates with bundles of long hairs (S. parasitica) and other Saprolegnia species was determined by means of an indirect immunofluorescence assay. Four of the Mabs used recognized some of the long-haired S. parasitica isolates but also cross-reacted with other Saprolegnia species without bundles of hairs and with Achlya sp. The other Mab (named 18A6) was able to differentiate between the asexual and most of the sexual isolates in the group of long-haired S. parasitica isolates, but did not recognize Achlya sp. or the Saprolegnia species without bundles of hairs, with the exception of S. hypogyna. These results indicate that isolates with bundles of long hairs are closely related with other members of genus Saprolegnia and share several antigens. However, Mab 18A6 seems to recognize an epitope that is expressed mainly in the asexual isolates in the long-haired S. parasitica isolates.S

Fungi isolated from cultured eggs, alevins and broodfish of brown trout in a hatchery affected by saprolegniosis

P. 510-518The aquatic fungi cultured from eggs, alevins and broodfish of brown trout Salmo trutta belonged to the genus Saprolegnia and were identified as S. diclina, S. australis, S. ferax, S. furcata, S. hypogyna, S. unispora and S. parasitica. The species obtained from infected eggs and alevins were different to those from infected fish. Several Saprolegnia species were isolated from eggs and alevins, whereas all the isolates obtained from broodfish were the pathogenic S. parasitica.S

Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.

Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited

Cross-sectional sero-epidemiological survey of sarcoptic mange in sheep of Wertern Castile and Leon, Spain

6 páginas, 3 tablas.The aim of the present study was to determine the prevalence of Sarcoptes scabiei-infection of ovine livestock in three provinces (Leon, Zamora and Salamanca) in the Western part of the Castile and Leon region in Spain, and to determine the association between different variables and seropositivity. A total of 3730 sheep sera from 373 flocks (10 sera from each flock) collected from May to September over the course of the years 2006 and 2007 were individually analysed by an indirect antibody ELISA validated for diagnosing sarcoptic mange in sheep. The overall flock-level true prevalence was 22.6% (95% CI: 17.8-27.4), the overall individual-level true prevalence within the total flocks was 7.2% (95% Cl: 6.1-8.3) and the overall individual-level true prevalence within the seropositive flocks was 31.3% (95% Cl: 27.2-35.4). The apparent prevalences, at flock-level and at individual-level within the total flocks and within the seropositive flocks, were not statistically different (p > 0.05) when the primary production objective of the flock is milk vs. meat, or in smaller (276 sheep). The apparent prevalences, at flock-level and at individual-level within the seropositive flocks, were, likewise, not statistically different between the three provinces, but the individual-level apparent prevalence within the total flocks showed significant variation from one province to another (p < 0.05). Sheep maintained in the Provinces of Zamora and Salamanca had greater odds (OR = 1.7, 95% Cl: 1.2-2.6; OR = 1.9, 95% Cl: 1.3-2.8, respectively) of being seropositive than those located in Leon Province (OR = 1.0). The findings of the present study clearly show the need to implement in this region effective control measures against sarcoptic mange in sheep.The present study was financially supported by grant LE010A05 of the Education Bureau of the Castile and Leon Regional Government (Consejería de Educación de la Junta de Castilla y León). FRC and MTCG are fellowship holders co-financed by the Education Bureau of the Castile and Leon Regional Government and the European Social Fund.Peer reviewe

Development and evaluation of an antibody ELISA for sarcoptic mange in sheep and a comparison with the skin-scraping method

11 páginas, 6 tablas, 4 figuras.In this work an indirect ELISA for detecting serum-specific IgG antibodies in sheep was developed using a crude saline extract from Sarcoptes scabiei var. ovis mites and then the repeatability of the ELISA outcomes was estimated. Subsequently, its diagnostic accuracy was evaluated by Receiver Operating Characteristics (ROC) analysis using a sample collected from the entire sheep population of western Castile and Leon region in Spain, and then compared with that of the skin-scraping method. The reference method used was a combination of clinical examination, skin-scraping analysis and epidemiological surveys, but it introduced selection and probably information biases. Furthermore, we attempted to identify biological factors useful to predict the sensitivity or specificity of the ELISA as determined by comparison with the reference method. Additionally, conventional latent-class analysis [Hui, S.L, Walter, S.D., 1980. Estimating the error rates of diagnostic tests. Biometrics 36, 167-171] was also used to estimate accuracy parameters. The between-run coefficient of variation (CV) for a standard serum was 8.8% and the within-run CV 4.3%. No significant deviation between the OD% means and strength positive correlation between the OD% values (r = 0.98) were found for the results from two different batches of antigen. When compared to the reference method, the Area Under the ROC curve (AUC) for the reference population was 0.967 (95% CI: 0.949-0.985) for the ELISA and 0.915 (95% CI: 0.863-0.968) for the skin-scraping method. By logistic regression analysis, one explanatory biological factor result to the skin-scraping method and four explanatory biological factors-Tyroglyphidae individual status, Trichophyton verrucosum individual status. Oestrus ovis status of the flock and presence of adjacent animals with a clinical disease neighbour to S. scubiei infection-were found for diagnostic sensitivity and specificity of the ELISA, respectively, although this depended on the OD% cut-off value used. Latent-class analysis, carried out for the ELISA at 17.8 OD% cut-off value (mean plus 3 SDs of sheep considered negative to anti-S. scabiei antibodies), showed a marked difference between the estimated diagnostic sensitivity of the ELISA (87.6%) and the skin-scraping method (62.8%), but closer diagnostic specificities (95.9% vs. 100%, respectively). These results demonstrate that the developed ELISA is valid for different applications in clinical as well as in epidemiological contexts.The present study was financially supported by grant LE010A05 from the Education Bureau of the Castile and Leon Regional Government (Consejería de Educación de la Junta de Castilla y León). FRC and MTCG hold fellowships from the Education Bureau of the Castile and Leon Regional Government, co-financed by the European Social Fund.Peer reviewe

Development and evaluation of an antibody ELISA for sarcoptic mange in sheep and a comparison with the skin-scraping method

11 páginas, 6 tablas, 4 figuras.In this work an indirect ELISA for detecting serum-specific IgG antibodies in sheep was developed using a crude saline extract from Sarcoptes scabiei var. ovis mites and then the repeatability of the ELISA outcomes was estimated. Subsequently, its diagnostic accuracy was evaluated by Receiver Operating Characteristics (ROC) analysis using a sample collected from the entire sheep population of western Castile and Leon region in Spain, and then compared with that of the skin-scraping method. The reference method used was a combination of clinical examination, skin-scraping analysis and epidemiological surveys, but it introduced selection and probably information biases. Furthermore, we attempted to identify biological factors useful to predict the sensitivity or specificity of the ELISA as determined by comparison with the reference method. Additionally, conventional latent-class analysis [Hui, S.L, Walter, S.D., 1980. Estimating the error rates of diagnostic tests. Biometrics 36, 167-171] was also used to estimate accuracy parameters. The between-run coefficient of variation (CV) for a standard serum was 8.8% and the within-run CV 4.3%. No significant deviation between the OD% means and strength positive correlation between the OD% values (r = 0.98) were found for the results from two different batches of antigen. When compared to the reference method, the Area Under the ROC curve (AUC) for the reference population was 0.967 (95% CI: 0.949-0.985) for the ELISA and 0.915 (95% CI: 0.863-0.968) for the skin-scraping method. By logistic regression analysis, one explanatory biological factor result to the skin-scraping method and four explanatory biological factors-Tyroglyphidae individual status, Trichophyton verrucosum individual status. Oestrus ovis status of the flock and presence of adjacent animals with a clinical disease neighbour to S. scubiei infection-were found for diagnostic sensitivity and specificity of the ELISA, respectively, although this depended on the OD% cut-off value used. Latent-class analysis, carried out for the ELISA at 17.8 OD% cut-off value (mean plus 3 SDs of sheep considered negative to anti-S. scabiei antibodies), showed a marked difference between the estimated diagnostic sensitivity of the ELISA (87.6%) and the skin-scraping method (62.8%), but closer diagnostic specificities (95.9% vs. 100%, respectively). These results demonstrate that the developed ELISA is valid for different applications in clinical as well as in epidemiological contexts.The present study was financially supported by grant LE010A05 from the Education Bureau of the Castile and Leon Regional Government (Consejería de Educación de la Junta de Castilla y León). FRC and MTCG hold fellowships from the Education Bureau of the Castile and Leon Regional Government, co-financed by the European Social Fund.Peer reviewe

New records of Saprolegniaceae isolated from rainbow trout, from their eggs, and water in a fish farm from the State of México

AbstractTen species of the family Saprolegniaceae were isolated from the fish farm “El Zarco”, State of México, obtained from samples of influent and effluent water of the farm and from infected eggs and individual fish of rainbow trout. Two species belong to the genus Achlya and 8 to Saprolegnia. Saprolegnia ferax is recorded for the first time for the State of México. Achlya ambisexualis, A. heterosexualis, S. australis, S. diclinous, S. glomerata, S. parasitica, S. terrestris, S. uliginosa and S. unispora are cited for the first time from Mexico

Potential of DIVA vaccines for Fish

The expanding aquaculture industry continues to encounter major challenges from highly contagious viruses. Control and eradication measures for lethal and economically damaging notifiable viral diseases involve &lsquo;stamping out&rsquo; policies and surveillance strategies. Mass-culling of stock and restricted movement of fish and fish products, used to control the spread of notifiable diseases, has considerable impacts on the trade of fish products. Although effective, these measures are expensive and ethically complex and could possibly be reduced by emulating innovative vaccination strategies used by the terrestrial livestock industry. DIVA (differentiating infected from vaccinated animal) strategies provide a basis to vaccinate and contain disease outbreaks without compromising &lsquo;disease-free&rsquo; status, as antibodies induced during infection can be used to distinguish from those induced by vaccination. The potential and feasibility of DIVA vaccination in aquaculture is explored here with reference to DIVA strategies applied in higher vertebrates. Three economically important notifiable viruses, causing major problems in three different cultured fish industries, are considered. The increased availability and application of sophisticated biotechnology tools has enabled improved prophylaxis and serological diagnosis for control of viral haemorrhagic septicaemia in rainbow trout, infectious salmon anaemia in Atlantic salmon and koi herpesvirus disease in carp. Improving the specificity of serological diagnostics in aquaculture in conjunction with suitable vaccines could enable the application of DIVA strategies, but the immunological variation between different fish species and contrasting pathobiological characteristics of different viruses determines the feasibility and potential of such DIVA approaches for aquaculture industries