Hantavirus is a tripartite negative-sense RNA virus. It can infect humans through contaminated rodent excreta and causes two types of fatal human diseases: hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). China exhibits the highest HFRS occurrence rate in the world, and the Heilongjiang area is one of the most severely infected regions. To obtain additional insights into the genetic characteristics of hantaviruses in the port cities of the Heilongjiang area in China, a molecular epidemiological investigation of hantaviruses isolated from rodents was performed in 2014. A total of 649 rodents (11 murine species and 1 shrew species) were caught in 12 port cities in Heilongjiang. Among these rodents, the most common species was A. agrarius, and the second-most common was R. norvegicus. A viral gene PCR assay revealed the presence of two specific genotypes of hantavirus, referred to as Hantaan virus (HTNV) and Seoul virus (SEOV), and the positive SEOV infection rate was higher than that for HTNV. A genetic analysis based on partial M segment sequences indicated that all of the isolates belonging to SEOV could be assigned to two genetic lineages, whereas the isolate belonging to HTNV could be assigned to only one genetic lineage. These results suggested that HTNV and SEOV are circulating in A. agrarius and R. norvegicus in the port cities in the area of Heilongjiang, but SEOV may be the dominant common hantavirus.

H6 subtype avian influenza viruses are globally distributed and, in recent years, have been isolated with increasing frequency from both domestic and wild bird species as well as infected humans. Many reports have examined the viruses in the context of poultry or several wild bird species, but there is less information regarding their presence in migratory birds. Hemagglutination and hemagglutination inhibition tests were used to measure HA activity for different HA subtypes. Whole viral genomes were sequenced and analysed using DNAstar and MEGA 6 to understand their genetic evolution. Pathogenicity was evaluated using a mouse infection model. We isolated 13 strains of H6 virus from faecal samples of migratory waterfowl in Anhui Province of China in 2014. Phylogenetic analysis showed gene reassortment between Eurasian and North American lineages. Five of the identified H6 strains had the ability to infect mice without adaptation. Our findings suggest that regular surveillance of wild birds, especially migratory birds, is important for providing early warning and control of avian influenza outbreaks.

The Chinese attenuated equine infectious anemia virus (EIAV) vaccine has successfully protected millions of equine animals from EIA disease in China. Given that the induction of immune protection results from the interactions between viruses and hosts, a better understanding of the characteristics of vaccine strain infection and host responses would be useful for elucidating the mechanism of the induction of immune protection by the Chinese attenuated EIAV strain. In this study, we demonstrate in equine monocyte-derived macrophages (eMDM) that EIAVFDDV13, a Chinese attenuated EIAV strain, induced a strong resistance to subsequent infection by a pathogenic strain, EIAVUK3. Further experiments indicate that the expression of the soluble EIAV receptor sELR1, Toll-like receptor 3 (TLR3) and interferon β (IFNβ) was up-regulated in eMDM infected with EIAVFDDV13 compared with eMDM infected with EIAVUK3. Stimulating eMDM with poly I:C resulted in similar resistance to EIAV infection as induced by EIAVFDDV13 and was correlated with enhanced TLR3, sELR1 and IFNβ expression. The knock down of TLR3 mRNA significantly impaired poly I:C-stimulated resistance to EIAV, greatly reducing the expression of sELR1 and IFNβ and lowered the level of infection resistance induced by EIAVFDDV13. These results indicate that the induction of restraining infection by EIAVFDDV13 in macrophages is partially mediated through the up-regulated expression of the soluble viral receptor and IFNβ, and that the TLR3 pathway activation plays an important role in the development of an EIAV-resistant intracellular environment.

Human immunodeficiency virus (HIV)-1 has a unique integration profile in the human genome relative to murine and avian retroviruses. Equine infectious anemia virus (EIAV) is another well-studied lentivirus that can also be used as a promising retro-transfection vector, but its integration into its native host has not been characterized. In this study, we mapped 477 integration sites of the EIAV strain EIAV_FDDV13 in fetal equine dermal (FED) cells during in vitro infection. Published integration sites of EIAV and HIV-1 in the human genome were also analyzed as references. Our results demonstrated that EIAV_FDDV13 tended to integrate into genes and AT-rich regions, and it avoided integrating into transcription start sites (TSS), which is consistent with EIAV and HIV-1 integration in the human genome. Notably, the integration of EIAV_FDDV13 favored long interspersed elements (LINEs) and DNA transposons in the horse genome, whereas the integration of HIV-1 favored short interspersed elements (SINEs) in the human genome. The chromosomal environment near LINEs or DNA transposons potentially influences viral transcription and may be related to the unique EIAV latency states in equids. The data on EIAV integration in its natural host will facilitate studies on lentiviral infection and lentivirus-based therapeutic vectors.

As a member of the tumor necrosis factor receptor (TNFR) protein superfamily, equine lentivirus receptor 1 (ELR1) has been shown to be expressed in various equine cells that are permissive for equine infectious anemia virus (EIAV) replication. The EIAV Tat protein (eTat) activates transcription initiated at the viral long terminal repeat (LTR) promoter through a unique mechanism that requires the recruitment of the equine cyclin T1 (eCT1) cofactor into the viral TAR RNA target element. In vitro studies have demonstrated that mouse fibroblast cell lines (e.g., NIH 3T3 cells) that express the EIAV receptor ELR1 and eCT1 support the productive replication of EIAV. Therefore, we constructed transgenic eCT1- and ELR1-expressing mice to examine whether they support in vivo EIAV replication. For the first time, we constructed mice transgenic for ELR1 and eCT1. Real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis confirmed that ELR1 and eCT1 were expressed in the transgenic mouse tissues, particularly in the intestines, spleen and lymph nodes. Consistent with the results of EIAV infection in NIH 3T3 cells expressing ELR1 and eCT1, mouse embryonic fibroblasts (MEFs) from the transgenic mice could support EIAV replication. More importantly, this virus could infect and replicate in mouse blood monocyte-derived macrophages (mMDMs). Macrophages are the principle target cell of EIAV in its natural hosts. Furthermore, after the transgenic mice were inoculated with EIAV, the virus could be detected not only in the plasma of the circulating blood but also in multiple organs, among which, the spleen and lymph nodes were the predominant sites of EIAV replication. Finally, we found that consistent with high viral replication levels, the relevant pathological changes occurred in the spleen and lymph nodes. Our results show that mice transgenic for ELR1 and eCT1 are susceptible to EIAV infection and replication. Further, EIAV infection can cause lesions on the spleen and lymph nodes, similar to those frequently observed in horses, the natural hosts. Therefore, ELR1 and eCT1 are essential in vivo for EIAV invasion and replication.