A Virulent PEDV Strain FJzz1 with Genomic Mutations and Deletions at the High Passage Level Was Attenuated in Piglets via Serial Passage In Vitro

Highly virulent porcine epidemic diarrhea virus(PEDV)strains re-emerged and circulated in China at the end of 2010,causing significant economic losses in the pork industry worldwide.To understand the genetic dynamics of PEDV during its passage in vitro,the PEDV G2 strain FJzzl was serially propagated in Vero cells for up to 200 passages.The susceptibility and adaptability of the FJzzl strain increased gradually as it was serially passaged in vitro.Sequence analysis revealed that amino acid(aa)changes were mainly concentrated in the S glycoprotein,which accounted for 72.22%-85.71%of all aa changes.A continuous aa deletion(^(55)I^(56)G^(57)E→^(55)K^(56)Δ^(57)Δ)occurred in the N-terminal domain of S1(Sl-NTD).To examine how the aa changes affected its virulence,FJzzl-F20 and FJzzl-F200 were selected to simultaneously evaluate their pathogenicity in suckling piglets.All the piglets in the FJzzl-F20-infected group showed typical diarrhea at 24 h postinfection,and the piglets died successively by 48 h postinfection.However,the clinical signs of the piglets in the FJzzl-F200-infected group were significantly weaker,and no deaths occurred.The FJzzl-F200-infected group also showed a lower level of fecal viral shedding and lower viral loads in the intestinal tissues,and no obvious histopathological lesions.TypeⅠandⅢinterferon were induced in the FJzzl-F200 infection group,together with pro-inflammatory cytokines,such as TNF-α,IL-1βand IL-8.These results indicate that the identified genetic changes may contribute to the attenuation of FJzzl strain,and the attenuated FJzzl-F200 may have the potential for developing PEDV live-attenuated vaccines.

The Novel PRRSV Strain HBap4-2018 with a Unique Recombinant Pattern Is Highly Pathogenic to Piglets

Currently, various porcine reproductive and respiratory syndrome virus(PRRSV) variants emerged worldwide with different genetic characteristics and pathogenicity, increasing the difficulty of PRRS control. In this study, a PRRSV strain named HBap4-2018 was isolated from swine herds suffering severe respiratory disease with high morbidity in Hebei Province of China in 2018. The genome of HBap4-2018 is 15,003 nucleotides in length, and compared with NADC30-like PRRSV, nsp2 of HBap4-2018 has an additional continuous deletion of five amino acids. Phylogenetic analysis based on complete genome and ORF5 showed that HBap4-2018 belonged to lineage 8 of PRRSV-2, which was characterized by highly variable genome. However, HBap4-2018 was classified into lineage 1 based on phylogenetic analysis of nsp2,sharing higher amino acid homology(85.3%–85.5%) with NADC30-like PRRSV. Further analysis suggested that HBap4-2018 was a novel natural recombinant PRRSV with three recombinant fragments in the genome, of which highly pathogenic PRRSV(HP-PRRSV) served as the major parental strains, while NADC30-like PRRSV served as the minor parental strains. Five recombination break points were identified in nsp2, nsp3, nsp5, nsp9 and ORF6, respectively,presenting a novel recombinant pattern in the genome. Piglets inoculated with HBap4-2018 presented typical clinical signs with a mortality rate of 60%. High levels of viremia and obvious macroscopic and histopathological lesions in the lungs were observed, revealing the high pathogenicity of HBap4-2018 in piglets.

Genetic characterization and pathogenicity of a reassortant Eurasian avian-like H1N1 swine influenza virus containing an internal gene cassette from 2009 pandemic H1N1 virus

Dear editor,Swine influenza virus(SIV)is a member of the Orthomyxoviridae family,influenza A virus genus,which can cause the swine influenza—an acute and highly contagious respiratory disease in pigs(Brown,2000;Kothalawala et al.,2006).The SIV was first observed in 1918 in the United States and the progenitor of the SIV was the H1N1 influenza virus which caused the Spanish influenza pandemic of 1918(Shope,1931).

中国植被变绿对夏季区域气候的影响

2000~2017年,卫星观测数据表明中国部分地区经历了显著的地表植被变绿,揭示植被变绿对气候和环境的影响势在必行.但当前粗分辨率的全球气候模式研究表明,植被变绿对中国夏季气候的影响不显著,因此本文采用高分辨率的陆-气耦合区域气候模式评估了中国植被变绿对东亚区域气候的影响及其生物地球物理机制.研究结果表明,中国植被变绿降低了近地表气温,以中国北方最显著.通过与中国过去十几年观测到的气温变化进行比较表明,观测到的植被变绿在中国北方能够在一定程度上抵消全球变暖的影响.植被变绿同时也改变了东亚夏季风降水格局,特别是中国"北旱南涝"的不均衡分布.植被变绿能够显著增加中国北方夏季的降雨,这与近十几年观测到的北方夏季风降水有所增加基本一致.而在长江以南地区,变绿导致降水少量减少.此外,植被变绿对土壤水资源的影响在文中也作了简要讨论.