Tandem repeat sequence of duck circovirus serves as downstream sequence element to regulate viral gene expression

From obscurity to urgency: a comprehensive analysis of the rising threat of duck circovirus

Duck circovirus (DuCV) is a small, nonenveloped, single-stranded DNA virus with immunosuppressive effects on ducks that leads to slow growth and elevated mortality following mixed infections. Its infection manifests as feather loss, slow growth, swelling of respiratory tissue, and damage to immune organs in ducks. Although single infections with DuCV do not cause noticeable clinical symptoms, its ability to compromise the immune system and facilitate infections caused by other pathogens poses a serious threat to duck farming. Given the prevalence of this disease and the increasing infection rates in recent years, which have resulted in significant economic losses in duck farming and related sectors, research and control of DuCV infection have become especially important. The aim of this review is to provide a summary of the current understanding of DuCV, serving as a reference for subsequent research and effective control of the virus. We focus mainly on the genetics and molecular biology, epidemiology, clinical symptoms, and pathology of DuCV. Additionally, topics such as the isolation and culture of the virus, vaccines and antiviral therapies, diagnostics, and preventative measures are discussed.

Establishment of TaqMan-based real-time PCR assay for rapid detection of duck circovirus

Duck circovirus (DuCV) is widespread across the world and causes feather disorders in young ducks. It was identified as the causative pathogen of duck beak atrophy and dwarfism syndrome and primary sclerosing cholangitis. In this study, we aimed to establish a TaqMan-based real-time PCR assay to detect DuCV. The primers and probe were designed based on the conserved region of the DuCV Rep gene. After optimizing the reaction conditions, the minimum virus detection limit of the designed PCR technique was 39.4 copies/μL, 100 times that of conventional PCR (cPCR). No cross-reaction with six other common duck viruses was observed. The intra- and inter-assay variations were less than 1%. The detection rate of DuCV-positive clinical samples using TaqMan-based real-time PCR was higher than that using SYBR Green-based real-time PCR and cPCR. Collectively, these results showed that the established TaqMan-based real-time PCR detected DuCV with high sensitivity and specificity, and significant repeatability, making it suitable for clinical use. Hence, it may be used as a novel tool for the diagnosis and epidemiological investigation of DuCV.

Research Note: Development of rapid isothermal amplification assay for detection of duck circovirus

Duck circovirus disease (DuCVD) caused by duck circovirus (DuCV) continues to spread in recent years, which brings serious harm to the poultry industry, so early diagnosis of DuCVD is of great significance for the prevention and control of this disease. Specific primers and probes for DuCV were designed in this study. Reverse primers and probes were modified at the 5′ ends with biotin and fluorescein, respectively, and they were combined with dipsticks labeled with biotin antibodies and fluorescein antibodies to establish a recombinase-aided amplification-lateral flow dipstick (RAA-LFD) assay for detection of duck circovirus. By using this method, the reaction products reached detectable levels in about 20 min as a result of rapid amplification at a constant temperature of 37℃. The detection results could be observed by dripping the reaction products onto the dipstick within 2 to 3 min. The RAA-LFD method has good specificity and high sensitivity (10² copies/μL). Compared with conventional polymerase chain reaction (PCR), RAA-LFD has no power limit on the testing instrument, and is easy to use, saving more time and manpower, so it is more suitable for clinical detection.

A Chromosome-Scale Assembly of the Asian Honeybee Apis cerana Genome

Apis cerana is one of the main honeybee species in artificial farming, which is widely distributed in Asian countries. The genome of A. cerana has been sequenced by several different research groups using second generation sequencing technologies. However, it is still necessary to obtain more complete and accurate genome sequences. Here we present a chromosome-scale assembly of the A. cerana genome using single-molecule real-time (SMRT) Pacific Biosciences sequencing and high-throughput chromatin conformation capture (Hi-C) genome scaffolding. The updated assembly is 215.67 Mb in size with a contig N50 of 4.49 Mb, representing an 212-fold improvement over the previous Illumina-based version. Hi-C scaffolding resulted in 16 pseudochromosomes occupying 97.85% of the assembled genome sequences. A total of 10,741 protein-coding genes were predicted and 9,627 genes were annotated. Besides, 314 new genes were identified compared to the previous version. The improved high-quality A. cerana reference genome will provide precise sequence information for biological research of A. cerana.