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BackgroundPorcine epidemic diarrhea (PED) has increased in severity in China since 2010. To investigate further the infectivity, genetic diversity and molecular epidemiology of its causative agent, the porcine epidemic diarrhea virus (PEDV), we assessed 129 clinical samples, which were the intestinal tissue of piglets with severe diarrhea, from 17 cities in central China. Both the spike (S) glycoprotein (S1, 1–789 amino acids (aa)) and the full-length ORF3 gene of 21 representative field strains from 21 farms in 11 cities were sequenced and analysed.MethodsPEDV was detected by reverse transcription-polymerase chain reaction (RT-PCR), and S1 and ORF3 sequences were processed by the Clustal W method via DNAMAN 8 software, and phylogenetic trees were constructed by the neighbor-joining method using MEGA 6 software.ResultsThe prevalence of PEDV was 92.25% and was detected in 119 of 129 samples, with 94.03% (63 of 67) of pig farms harbouring the disease. According to the phylogenetic analysis of the S1 genes, our isolates all fell into group G2 (variants) and showed a close relationship to isolates from Chinese (HN1303, CH/ZMDZY/11 and AJ1102), Korean (AD01), American (MN, IA1, IA2 and 13–019349) sources, and these isolates differed genetically from other Chinese (LZC, CH/HNZZ/2011 and SD-M) and Korean (SM98) strains as well Japanese (83-P5 and MK) strains. In addition, our isolates differed from attenuated vaccine strains, CV777 (used in China) and DR13 (used in Korea). According to our derived amino acid sequence analysis, we detected one novel variant PEDV, viz: CH/HNLY, with 4-aa insertion/deletion (RSSS/T) at position 375 and 1-aa (D) deletion at position 430 compared to the CV777 attenuated strain. These mutations were located on the receptor binding domain. Our ORF3 gene analyses showed that the prevalent PEDV isolates were variants, and the isolated strains differed genetically from the vaccine strains.ConclusionsThese findings illustrated the existence of genetic diversity among geographically distinct PEDV strains, and our study has provided an impetus to conduct further research on the PEDV receptor binding protein and on the new and efficacious vaccines design.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-016-0646-8) contains supplementary material, which is available to authorized users.

Conversion of CO2 via hydrogenation to chemicals and fuels is deemed to be a promising route to utilize carbon sources. Iron-based catalysts are widely used in CO2 hydrogenation to produce value-added hydrocarbons. The prereduction and reaction conditions usually cause complicated evolution of iron phases. In this work, Fe3O4 nanoparticles with different particle sizes were synthesized to investigate the effects of the reduction and carburization behavior on the catalytic performance of iron-based catalysts during CO2 hydrogenation. It was demonstrated that larger Fe3O4 nanoparticles are more difficult to be reduced and carburized. Various iron species were formed in catalysts during the reaction, resulting in different catalytic performances. The high content of inactive α-Fe caused lower CO2 conversion and olefins-to-paraffins ratio (O/P) over larger Fe3O4 nanoparticles. The highest CO2 conversion (41.7%) and O/P (1.71) were obtained over the catalyst with the appropriate proportion of Fe3O4 and Fe5C2 phases.

Low proportion of essential amino acids (EAAs) is one of the barriers for animals to use phloem as a diet. Endosymbionts with EAAs synthesis functions are considered crucial for ameliorating the lack of EAAs in insects’ diets. In this study, we transferred the insects from a cabbage-reared Myzus persicae population onto 3 new plant species including eggplant, tobacco and spinach. The performance on these plants was evaluated and the dynamics of endosymbionts in relation to this host alternation were recorded. We found that the EAAs ratio in phloem was largely determined by the concentrations of non-essential amino acids and the higher proportion of EAAs seemed to favor the population establishment on new plant species and the growth of primary endosymbionts inside insects, which indicated that nitrogen quality was an important factor for aphids to infest and spread on new plant hosts.

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