MFI-Net: A multi-resolution fusion input network for retinal vessel segmentation.

Segmentation of retinal vessels is important for doctors to diagnose some diseases. The segmentation accuracy of retinal vessels can be effectively improved by using deep learning methods. However, most of the existing methods are incomplete for shallow feature extraction, and some superficial features are lost, resulting in blurred vessel boundaries and inaccurate segmentation of capillaries in the segmentation results. At the same time, the "layer-by-layer" information fusion between encoder and decoder makes the feature information extracted from the shallow layer of the network cannot be smoothly transferred to the deep layer of the network, resulting in noise in the segmentation features. In this paper, we propose the MFI-Net (Multi-resolution fusion input network) network model to alleviate the above problem to a certain extent. The multi-resolution input module in MFI-Net avoids the loss of coarse-grained feature information in the shallow layer by extracting local and global feature information in different resolutions. We have reconsidered the information fusion method between the encoder and the decoder, and used the information aggregation method to alleviate the information isolation between the shallow and deep layers of the network. MFI-Net is verified on three datasets, DRIVE, CHASE_DB1 and STARE. The experimental results show that our network is at a high level in several metrics, with F1 higher than U-Net by 2.42%, 2.46% and 1.61%, higher than R2U-Net by 1.47%, 2.22% and 0.08%, respectively. Finally, this paper proves the robustness of MFI-Net through experiments and discussions on the stability and generalization ability of MFI-Net.

[Isolation, identification and full-length genome sequence analysis of encephalomyocarditis virus from local aardvarks].

Encephalomyocarditis virus (EMCV) is a natural epidemic zoonotic pathogen. However, no reports have been published regarding the isolation, identification and full-length genome of EMCV from a local aardvark population. In present study, an EMCV isolate HNXX13 was isolated from aardvarks named Huainan-pig in Henan Province. The systematic identification, full-length genome sequencing and molecular characteristic analysis of the isolate HNXX13 were conducted. The result showed that the isolate was spherical with a diameter of 24-30 nm, neither heat- nor acid-resistant, sensitive to trypsin, insensitive to chloroform, not protected by bivalent cationic, and the specific fluorescence was observed in the cytoplasm of BHK-21 cells infected with the isolate by using indirect fluorescence assay. The full-length genome of EMCV HNXX13 generated a 7 725bp sequence (GenBank: F771002), with 81.0%-99.9% nucleotide identity to reference strains from different animals, and 99.5% with a Chinese reference strain isolated earlier from a commercial pig herd. The phylogenetic tree based on the full-length genome and ORF sequences identified that all EMCV strains were divided into three groups G1, G2 and G3, and strain HNXX13 belonging to the G1 group with other Chinese reference strains. The result also identified that this EMCV infection could cause severe clinical signs in a local aardvark population, and enriches the molecular epidemiological data of EMCV in China. Regional differences exist in EMCV genome and transmission is limited within a certain area. However, the cross-infection and transmission of EMCV between aardvark and mice appears most likely. Mutations have occurred in some amino acids of EMCV strain HNXX13 during the transmission in local aardvark herd and these mutations might make the virus easier to infect the aardvark.

[Investigation of etiology of massive infection with porcine pseudorabies virus in Henan and neighboring Provinces].

In early 2011, the serious outbreak of porcine pseudorabies virus (PRV) infection suddenly recurred in Henan and neighboring Provinces. To investigate the etiology of massive infection with PRV, 16 800 serum samples, 905 porcine epidemic diarrhea virus (PEDV) back-feeding tissues, and 56 PR gene deleted live vaccines were colleted from January 2011 to May 2013 to detect PRV field infection using a PRV gE antibody test kit. The gE and TK genes of 11 new epidemic PRV strains were sequenced by PCR, and their molecular characteristics were analyzed. Moreover, virus titer determination, protective test against PRV, and vaccine potency testing were performed. The results showed that the detection rate of PRV field infection-positive pig farms was 68.06%, and the overall positive rate of PRV field infection in serum was 38.47%; the positive rates in breeding sows, breeding boars, reserve pigs, and commercial pigs were 40.12%, 30.88%, 54.67%, and 26.52%, respectively. The new epidemic strains were in the same evolutionary branch and belonged to the virulent strain group. Compared with the classical PRV strain, the virulence of new epidemic strains changed a little. The length of gE gene was 1 787 bp, and the length of TK gene was 963 bp. The nucleotide homologies of gE and TK genes to Chinese reference strains were 98.2%-99.8% and 98.90%-99.6%, respectively, and the amino acid homologies were 97.1%-99.8% and 97.5%-99.4%, respectively. Commercial vaccine had a 100% protective effect against the new epidemic strains. The positive rate of PRV field infection was 0% in vaccine and 40.44% in back-feeding tissues. The results confirmed that PRV field infection rates were rising sharply among pigs in Henan and neighboring Provinces after 2011. The main virulence genes of new epidemic PRV strains did not change significantly over the years. PR gene deleted live vaccines had no PRV field infection and could completely resist the attack of new strains. The virus carriage of breeding boars and reserve pigs and the serious PRV field infection in PEDV back-feeding tissues were the main causative factors for massive infection with PRV and epidemic outbreak in Henan and neighboring Provinces from 2011 to 2013.

Immune responses of chickens inoculated with a recombinant fowlpox vaccine coexpressing HA of H9N2 avain influenza virus and chicken IL-18.

Control of the circulation of H9N2 avian influenza virus (AIV) is a major concern for both animal and public health, and H9N2 AIV poses a major threat to the chicken industry worldwide. Here, we developed a recombinant fowlpox virus (rFPV-HA) expressing the haemagglutinin (HA) gene of the A/CH/JY/1/05 (H9N2) influenza virus and a recombinant fowlpox virus (rFPV-HA/IL18) expressing the HA gene and chicken interleukin-18 (IL-18) gene. Recombinant plasmid pSY-HA/IL18 was constructed by cloning chicken IL-18 expression cassette into recombinant plasmid pSY-HA containing the HA gene. Two rFPVs were generated by transfecting two recombinant plasmids into the chicken embryo fibroblast cells pre-infected with S-FPV-017, and assessed for their immunological efficacy on one-day-old White Leghorn specific-pathogen-free chickens challenged with the A/CH/JY/1/05 (H9N2) strain. There was a significant difference in HI antibody levels (P<0.05) elicited by either rFPV-HA or rFPV-HA/IL18. The level of splenocyte proliferation response in the rFPV-HA/IL18-vaccinated group was significantly higher (P<0.05) than that in the rFPV-HA group. After challenge with 10(6.5)ELD(50) H9N2 AIV 43days after immunization, rFPVs vaccinated groups could prevent virus shedding and replication in multiple organs in response to H9N2 AIV infection, and rFPV-HA/IL18 vaccinated group had better inhibition of viruses than rFPV-HA vaccinated group. Our results show that the protective efficacy of the rFPV-HA vaccine could be enhanced significantly by simultaneous expression of IL-18.