猪圆环病毒2型相关疾病的临床诊断和控制新知

圆环病毒2型及相关疾病主要影响断奶仔猪和生长肥育阶段的猪只,导致其增重下降;该病也可造成猪只的繁殖疾病,严重影响养猪的经济效益。本文介绍了猪圆环病毒2型相关疾病的临床诊断及其控制措施。

Establishing the Tolerability to Turkeys of Nonanoic Acid at Practical Levels of Use as a Feed Flavoring

Objective: Nonanoic acid (NA) is one of a series of straight-chain aliphatic alcohols, aldehydes, acids and their derivatives with a well-documented history of use as a synthetic flavoring in human food. As part of a safety evaluation of NA for use as a flavoring in animal feed, an experiment was conducted to evaluate the ability of turkeys to tolerate NA at levels relevant to practical feeding practices. Materials and Methods: A total of 594-day-old BUT Premium turkeys (300 males and 294 females) were allocated at random to 40 floor pens containing either 15 males or 13 to 15 females. Poults were fed one of 4 treatment diets in crumble (0 to 14 days) or pellet (15 to 59 days) form containing 0 (control), 100, 300 or 1000 mg NA/kg complete feed for 59 days. General health and performance were monitored for the duration of the study. At days 57 and 59 of age, blood samples were taken and birds were sacrificed and necropsied for histopathological examination of the digestive tract. Significant differences were considered at P ≤ 0.05 and near-significant trends at P ≤ 0.10. Results: NA had no effect on mortality (Pχ2 = 0.54), average daily feed intake (ADFI) (P = 0.11), average daily gain (ADG) (P = 0.12) or feed conversion ratio (FCR) (P = 0.45) in poults over the 56-day feeding period. No treatment-related effects on blood parameters or tissue pathology were observed. Conclusion: The results of the study support the safety and tolerance of NA to turkeys at dietary levels of up to 1000 mg/kg which will provide a considerable margin of safety compared to anticipated practical conditions of use as a feed flavoring.

Narrow versus broad:sexual dimorphism in the wing form of western European species of the subgenus Avaritia(Culicoides,Ceratopogonidae)

While wing form is known to differ between males and females of the genus Culicoides,detailed studies of sexual dimorphism are lacking.In this study,we analyze sex-specific differences in the wing form of 5 species of the subgenus Avaritia,using geometric morphometrics and comparative phylogenetic methods.Our results confirm the existence of marked sexual dimorphism in the wing form of the studied species and reveal for the first time that while there is a shared general pattern of sexual shape dimorphism within the subgenus,sexual size dimorphism,and particular features of sexual shape dimorphism differ among species.Sexual shape dimorphism was found to be poorly associated to size and the evolutionary history of the species.The tight association of sexual shape dimorphism with aspect ratio suggests that the shape of the wing is optimized for the type of flight of each sex,that is,dispersal flight in females versus aerobatic flight in males.Moreover,the fact that interspecific shape differences are greater and more strongly associated to aspect ratio in males than in females might be indicating that in males the selective pressures affecting flight performance characteristics are more heterogeneous and/or stronger than in females among the studied species.

Modeling the impact of surveillance activities combined with physical distancing interventions on COVID-19 epidemics at a local level

Physical distancing and contact tracing are two key components in controlling the COVID-19 epidemics.Understanding their interaction at local level is important for policymakers.We propose a flexible modeling framework to assess the effect of combining contact tracing with different physical distancing strategies.Using scenario tree analyses,we compute the probability of COVID-19 detection using passive surveillance,with and without contact tracing,in metropolitan Barcelona.The estimates of detection probability and the frequency of daily social contacts are fitted into an age-structured susceptible-exposed-infectious-recovered compartmental model to simulate the epidemics considering different physical distancing scenarios over a period of 26 weeks.With the original Wuhan strain,the probability of detecting an infected individual without implementing physical distancing would have been 0.465,0.515,0.617,and 0.665 in designated age groups(0e14,15e49,50e64,and>65),respectively.As the physical distancing measures were reinforced and the disease circulation decreased,the interaction between the two interventions resulted in a reduction of the detection probabilities;however,despite this reduction,active contact tracing and isolation remained an effective supplement to physical distancing.If we relied solely on passive surveillance for diagnosing COVID-19,the model required a minimal 50%(95%credible interval,39e69%)reduction of daily social contacts to keep the infected population under 5%,as compared to the 36%(95%credible interval,22e56%)reduction with contact tracing systems.The simulation with the B.1.1.7 and B.1.167.2 strains shows similar results.Our simulations showed that a functioning contact tracing program would reduce the need for physical distancing and mitigate the COVID-19 epidemics.

SARS-CoV-2 interaction with Siglec-1 mediates trans-infection by dendritic cells

Antigen-presenting cells(APCs)may be resistant to SARS-CoV-2 infection but still contribute to viral pathogenesis.Lectins such as sialic acid-binding Ig-like lectin 1(Siglec-1/CD169)mediate the attachment of viruses to APCs.Here,we show that APCs effectively capture SARS-CoV-2 within compartments via recognition of Siglec-1.This receptor interacts with sialylated gangliosides on membranes of SARS-CoV-2 variants.