Ehrlichia minasensis, a recently described Ehrlichia species that is the most closely related to, but clearly distinct from, Ehrlichia canis, has been circulating in not only bovines, cervids, and dogs but also several tick species from Canada, Brazil, France, Pakistan, Ethiopia, and Israel. However, there are no reports of E. minasensis in China. The purpose of this study was to explore whether E. minasensis is present naturally in ticks in China. Through PCR targeting of the genus-conserved dsb gene, E. minasensis DNA was detected in Haemaphysalis hystricis ticks removed from free-ranging sheep in Hainan Province, South China in 2017. The partial sequence of the dsb, 16S rRNA, and groEL genes demonstrated that the Hainan strain shared 99% identity with the dsb gene of E. minasensis strain UFMG-EV (GenBank: JX629808), with the 16S rRNA of E. minasensis isolate E-2650 (MH500005) and with the groEL gene of E. minasensis strain UFMG-EV (JX629806), respectively. Moreover, sequence analysis of the major immunogenic tandem repeat protein (trp36) revealed that the Hainan strain harbored a unique tandem repeat sequence (APEAAPVSAPEAAPVSAPVS) and a C-terminal region that differed from those of other known E. minasensis strains. Additionally, phylogenetic analysis based on the entire amino acid sequence of trp36 revealed that the Hainan strain was closely related to a recently described E. minasensis strain from Brazil, of which the sister clade contained different strains of E. canis. The discovery of this novel Hainan strain in H. hystricis ticks represents the first known natural presence of E. minasensis in South China, highlighting the need for its constant surveillance.

Avian orthoavulavirus 13 (AOAV-13), also named avian paramyxovirus 13 (APMV-13), has been found sporadically in wild birds around the world ever since the discovery of AOAV-13 (AOAV-13/wild goose/Shimane/67/2000) in a wild goose from Japan in 2000. However, there are no reports of AOAV-13 in China. In the present study, a novel AOAV-13 virus (AOAV-13/wild goose/China/Hubei/V93-1/2015), isolated from a wild migratory waterfowl in a wetland of Hubei province of China, during active surveillance from 2013 to 2018, was biologically and genetically characterized. Phylogenetic analyses demonstrated a very close genetic relationship among all AOAV-13 strains, as revealed by very few genetic variations. Moreover, pathogenicity tests indicated that the V93-1 strain is a low virulent virus for chickens. However, the genome of the V93-1 virus was found to be 16,158 nucleotides (nt) in length, which is 12 nt or 162 nt longer than the other AOAV-13 strains that have been reported to date. The length difference of 12 nt in strain V93-1 is due to the existence of three repeats of the conserved sequence, “AAAAAT”, in the 5′-end trailer of the genome. Moreover, the HN gene of the V93-1 virus is 2,070 nt in size, encoding 610 aa, which is the same size as the AOAV-13 strain from Japan, whereas that of two strains from Ukraine and Kazakhstan are 2,080 nt in length, encoding 579 aa. We describe a novel AOAV-13 in migratory waterfowl in China, which suggests that diversified trailer region sequences and HN gene lengths exist within serotype AOAV-13, and highlight the need for its constant surveillance in poultry from live animal markets, and especially migratory birds.

No abstract

Vaccines with live, low-virulence Newcastle disease virus (NDV) strains are still the most accepted prevention and control strategies for combating Newcastle disease (ND), a major viral disease that hampers the development of the poultry industry worldwide. However, the mechanism underlying vaccine-mediated innate cell immune responses remains unclear. Here, a high-throughput Illumina sequencing approach was employed to determine cellular miRNA expression profiles in chicken macrophages infected with the LaSota virus, a widely used vaccine strain for mass vaccination programs against ND in poultry. Compared to the control group, 112 and 115 differentially expressed (DE) miRNAs were identified at 24 hpi (hours post inoculation) and 48 hpi, respectively. Meanwhile, 174 DE miRNAs were identified between 24 hpi and 48 hpi. Furthermore, 12 upregulated and 6 downregulated DE miRNAs were observed in common at 24 and 48 hpi compared with 0 hpi. In addition, target prediction and functional analysis of these DE miRNAs revealed significant enrichment for several signaling pathways, especially in the immune-related genes and pathways, such as the RIG-I-like receptor signaling pathway, NOD-like receptor signaling pathway, and mitogen-activated protein kinase (MAPK) signaling pathway. Our findings not only lay the foundations for further investigating the roles and regulatory mechanisms of miRNA in vaccine-mediated innate cellular immune responses, but also extend new insights into the interactions between the host and NDV infection.

The highly virulent Newcastle disease virus (NDV) isolates typically result in severe systemic pathological changes and high mortality in Newcastle disease (ND) illness, whereas avirulent or low-virulence NDV strains can cause subclinical disease with no morbidity and even asymptomatic infections in birds. However, understanding the host’s innate immune responses to infection with either a highly virulent strain or an avirulent strain, and how this response may contribute to severe pathological damages and even mortality upon infection with the highly virulent strain, remain limited. Therefore, the differences in epigenetic and pathogenesis mechanisms between the highly virulent and avirulent strains were explored, by transcriptional profiling of chicken embryonic visceral tissues (CEVT), infected with either the highly virulent NA-1 strain or the avirulent vaccine LaSota strain using RNA-seq. In our current paper, severe systemic pathological changes and high mortality were only observed in chicken embryos infected with the highly virulent NA-1 strains, although the propagation of viruses exhibited no differences between NA-1 and LaSota. Furthermore, virulent NA-1 infection caused intense innate immune responses and severe metabolic disorders in chicken EVT at 36 h post-infection (hpi), instead of 24 hpi, based on the bioinformatics analysis results for the differentially expressed genes (DEGs) between NA-1 and LaSota groups. Notably, an acute hyperinflammatory response, characterized by upregulated inflammatory cytokines, an uncontrolled host immune defense with dysregulated innate immune response-related signaling pathways, as well as severe metabolic disorders with the reorganization of host–cell metabolism were involved in the host defense response to the CEVT infected with the highly virulent NA-1 strain compared to the avirulent vaccine LaSota strain. Taken together, these results indicate that not only the host’s uncontrolled immune response itself, but also the metabolic disorders with viruses hijacking host cell metabolism, may contribute to the pathogenesis of the highly virulent strain in ovo.