Phylogenetic analysis of porcine parvoviruses from swine samples in China

<p>Abstract</p> <p>Background</p> <p>Porcine parvovirus (PPV) usually causes reproductive failure in sows. The objective of the present study was to analyze the phylogenetic distribution and perform molecular characterization of PPVs isolated in China, as well as to identify two field strains, LZ and JY. The data used in this study contained the available sequences for NS1 and VP2 from GenBank, as well as the two aforementioned Chinese strains.</p> <p>Results</p> <p>Phylogenetic analysis shows that the PPV sequences are divided into four groups. The early Chinese PPV isolates are Group I viruses, and nearly all of the later Chinese PPV isolates are Group II viruses. LZ belongs to group II, whereas the JY strain is a Group III virus. This is the first report on the isolation of a Group III virus in China. The detection of selective pressures on the PPV genome shows that the NS1 and VP2 genes are under purifying selection and positive selection, respectively. Moreover, the amino acids in the VP2 capsid are highly variable because of the positive selection.</p> <p>Conclusions</p> <p>Our study provides new molecular data on PPV strains in China, and emphasizes the importance of etiological studies of PPV in pigs.</p

Polymorphic genetic characterization of the ORF7 gene of porcine reproductive and respiratory syndrome virus (PRRSV) in China

<p>Abstract</p> <p>Background</p> <p>Porcine reproductive and respiratory syndrome virus (PRRSV) exhibits extensive genetic variation. The outbreak of a highly pathogenic PRRS in 2006 led us to investigate the extent of PRRSV genetic diversity in China. To this end, we analyzed the Nsp2 and ORF7 gene sequences of 98 Chinese PRRSV isolates.</p> <p>Results</p> <p>Preliminary analysis indicated that highly pathogenic PRRSV strains with a 30-amino acid deletion in the Nsp2 protein are the dominant viruses circulating in China. Further analysis based on ORF7 sequences revealed that all Chinese isolates were divided into 5 subgroups, and that the highly pathogenic PRRSVs were distantly related to the MLV or CH-1R vaccine, raising doubts about the efficacy of these vaccines. The ORF7 sequence data also showed no apparent associations between geographic or temporal origin and heterogeneity of PRRSV in China.</p> <p>Conclusion</p> <p>These findings enhance our knowledge of the genetic characteristics of Chinese PRRSV isolates, and may facilitate the development of effective strategies for monitoring and controlling PRRSV in China.</p

In-vitro and in-vivo phenotype of type Asia 1 foot-and-mouth disease viruses utilizing two non-RGD receptor recognition sites

<p>Abstract</p> <p>Background</p> <p>Foot-and-mouth disease virus (FMDV) uses a highly conserved Arg-Gly-Asp (RGD) triplet for attachment to host cells and this motif is believed to be essential for virus viability. Previous sequence analyses of the 1D-encoding region of an FMDV field isolate (Asia1/JS/CHA/05) and its two derivatives indicated that two viruses, which contained an Arg-Asp-Asp (RDD) or an Arg-Ser-Asp (RSD) triplet instead of the RGD integrin recognition motif, were generated serendipitously upon short-term evolution of field isolate in different biological environments. To examine the influence of single amino acid substitutions in the receptor binding site of the RDD-containing FMD viral genome on virus viability and the ability of non-RGD FMDVs to cause disease in susceptible animals, we constructed an RDD-containing FMDV full-length cDNA clone and derived mutant molecules with RGD or RSD receptor recognition motifs. Following transfection of BSR cells with the full-length genome plasmids, the genetically engineered viruses were examined for their infectious potential in cell culture and susceptible animals.</p> <p>Results</p> <p>Amino acid sequence analysis of the 1D-coding region of different derivatives derived from the Asia1/JS/CHA/05 field isolate revealed that the RDD mutants became dominant or achieved population equilibrium with coexistence of the RGD and RSD subpopulations at an early phase of type Asia1 FMDV quasispecies evolution. Furthermore, the RDD and RSD sequences remained genetically stable for at least 20 passages. Using reverse genetics, the RDD-, RSD-, and RGD-containing FMD viruses were rescued from full-length cDNA clones, and single amino acid substitution in RDD-containing FMD viral genome did not affect virus viability. The genetically engineered viruses replicated stably in BHK-21 cells and had similar growth properties to the parental virus. The RDD parental virus and two non-RGD recombinant viruses were virulent to pigs and bovines that developed typical clinical disease and viremia.</p> <p>Conclusions</p> <p>FMDV quasispecies evolving in a different biological environment gained the capability of selecting different receptor recognition site. The RDD-containing FMD viral genome can accommodate substitutions in the receptor binding site without additional changes in the capsid. The viruses expressing non-RGD receptor binding sites can replicate stably in vitro and produce typical FMD clinical disease in susceptible animals.</p

Clinical Significance of ROS1 Rearrangements in Non-small Cell Lung Cancer

Chromosomal rearrangements involving the ROS1 receptor tyrosine kinase gene have recently been described in multiple malignancies, including non-small cell lung cancer (NSCLC). ROS1 rearrangement defines a new molecular subset of NSCLC with the prevalence of ROS1 rearrangements around 1%-2%. ROS1-positive NSCLCs arise in young never-smokers with adenocarcinoma that are similar to those observed in patients with ALK-rearranged NSCLC. Crizotinib demonstrates in vitro activity and early clinical trial shows marked antitumor activity in ROS1-rearranged patients. The overall response rate is around 56% and the disease control rate at 8 weeks is about 76%. Further understanding the ROS1 fusions in the pathogenesis of NSCLC, methods to detect ROS1 rearrangements, and targeting ROS1-rearranged NSCLC patients with specific kinase inhibitors would lead to an era of personalized medicine

The molecular characteristic analysis of PRRSV GSWW/2015 strain and its pathogenicity to pigs

Abstract Background Porcine reproductive and respiratory syndrome (PRRS) is a severe disease, causing great economic losses to the pig industry. The causative agent, porcine reproductive and respiratory syndrome virus (PRRSV) is highly variable. Since the emergence of highly pathogenic PRRSV (HP-PRRSV) in China in 2006, this virus strain has undergone extensive variation. To investigate the genetic variation and pathogenicity of currently isolated PRRSV GSWW/2015 strain, its whole genome was sequenced and analyzed for the specific variation in NSP2, GP3 and GP5 regions. Pigs were challenged with the isolated virus to investigate its pathogenicity. Methods The PRRSV GSWW/2015 strain was isolated by seeding the viral material in Marc-145 cells. The virus specific cytopathic effect (CPE) was confirmed by indirect immunofluorescent assay (IFA) and PCR to detect the virus protein and RNA. Nine pairs of primers were designed to obtain the complete genome by PCR. All PCR fragments were cloned into T-vector for sequencing. The genetic variation of GSWW/2015 strain was analyzed by multiple sequence alignments. Nineteen PRRSV-free piglets were intranasally challenged with 108 copies of GSWW virus, while seven piglets were housed together as contact-infected control. Clinical signs were recorded daily after challenge. Blood samples were obtained every week and the viral titer was detected by quantitative real-time PCR (qRT-PCR). The PRRSV specific antibody was detected by LSI ELISA kit. Results The complete genome of PRRSV GSWW/2015 strain (GenBank accession number KX767091) was obtained. The whole genome of this strain shares 88.5 and 60.6% identity with VR-2332 and LV respectively, indicating that it belongs to the North American type (NA-type). Sequence alignments revealed that GSWW/2015 strain has a discontinuous deletion of 30 amino acids in NSP2, which is similar with HP-PRRSV. Some amino acids mutations can be observed in antigenic epitope regions of GP3 and GP5 compared with earlier strains of HP-PRRSV. Some piglets showed typical clinical signs of PRRSV after challenge. Only four pigs showed viremia within 3 days after challenge, most pigs showed peaked viremia after 21–28 days including 7 contact-infected pigs. Two pigs were detected to be positive for antibody to PRRSV at 14 days post infection (DPI), and 11 pigs (11/26) show seroconversion for PRRSV at 49 DPI. Twelve piglets died of PRRSV infection within two months. Conclusions The genome of PRRSV GSWW/2015 strain shows the features of HP-PRRSV with 30 discontinuous amino acids deletion in NSP2 and some new amino acid mutations in epitope regions of GP5 and GP3, which might alter the antigenicity of the virus. Furthermore, the virus showed high virulence to piglets as reported in HP-PRRSV, and induced long-lasting viremia and low level of antibody responses. This work further enriched our knowledge on PRRSV evolution and pathogenicity

Evaluation of a genetically modified foot-and-mouth disease virus vaccine candidate generated by reverse genetics

Abstract Background Foot-and-mouth disease (FMD) is the most economically important and highly contagious disease of cloven-hoofed animals worldwide. Control of the disease has been mainly based on large-scale vaccinations with whole-virus inactivated vaccines. In recent years, a series of outbreaks of type O FMD occurred in China (including Chinese Taipei, Chinese Hong Kong) posed a tremendous threat to Chinese animal husbandry. Its causative agent, type O FMDV, has evolved into three topotypes (East–South Asia (ME-SA), Southeast Asia (SEA), Cathay (CHY)) in these regions, which represents an important obstacle to disease control. The available FMD vaccine in China shows generally good protection against ME-SA and SEA topotype viruses infection, but affords insufficient protection against some variants of the CHY topotype. Therefore, the choice of a new vaccine strain is of fundamental importance. Results The present study describes the generation of a full-length infectious cDNA clone of FMDV vaccine strain and a genetically modified virus with some amino acid substitutions in antigenic sites 1, 3, and 4, based on the established infectious clone. The recombinant viruses had similar growth properties to the wild O/HN/CHA/93 virus. All swine immunized with inactivated vaccine prepared from the O/HN/CHA/93 were fully protected from challenge with the viruses of ME-SA and SEA topotypes and partially protected against challenge with the virus of CHY topotype at 28 days post-immunization. In contrast, the swine inoculated with the genetically modified vaccine were completely protected from the infection of viruses of the three topotypes. Conclusions Some amino acid substitutions in the FMDV vaccine strain genome did not have an effect on the ability of viral replication in vitro. The vaccine prepared from genetically modified FMDV by reverse genetics significantly improved the protective efficacy to the variant of the CHY topotype, compared with the wild O/HN/CHA/93 virus. Thus, the full-length cDNA clone of FMDV can be a useful tool to develop genetically engineered FMDV vaccine candidates to help control porcinophilic FMD epidemics in China.</p