Genome characterization of two NADC30-like porcine reproductive and respiratory syndrome viruses in China.

Background: The recent emergence of NADC30-like porcine reproductive and respiratory syndrome virus (PRRSV) in vaccinated pigs arose more attentions for the high incidents of mutation and recombination of PRRSVs.

Findings: In this study, we determined full-length genome sequences of two NADC30-like PRRSV isolates from recent PRRSV outbreaks in China. Phylogenetic analysis showed that these two isolates were clustered in an independent branch together with NADC30, an American isolate in 2008.

Establishment and application of a competitive enzyme-linked immunosorbent assay differentiating PCV2 antibodies from mixture of PCV1/PCV2 antibodies in pig sera.

Background: Porcine cirovirus type 1 (PCV1) and type 2 (PCV2) are circulating in Chinese pig herds and the infected pigs develop antibodies to both viruses. Current commercial available ELISA kits cannot differentiate PCV2-specific antibodies from the mixtures of PCV1 and PCV2 antibodies in PCV1/2-infected or PCV2-vaccinated pigs. Therefore, the need for developing PCV2-specific ELISA methods is urgent to evaluate PCV2 antibody level in exclusion of PCV1 antibody interference after PCV2 vaccination.

Label-free immunoassay for porcine circovirus type 2 based on excessively tilted fiber grating modified with staphylococcal protein A.

Using excessively tilted fiber grating (Ex-TFG) inscribed in standard single mode fiber, we developed a novel label-free immunoassay for specific detection of porcine circovirus type 2 (PCV2), which is a minim animal virus. Staphylococcal protein A (SPA) was used to modify the silanized fiber surface thus forming a SPA layer, which would greatly enhance the proportion of anti-PCV2 monoclonal antibody (MAb) bioactivity, thus improving the effectiveness of specific adsorption and binding events between anti-PCV2 MAbs and PCV2 antigens. Immunoassay experiments were carried out by monitoring the resonance wavelength shift of the proposed sensor under different PCV2 titer levels.

Development of a Monoclonal Antibody Against Porcine Circovirus2 Cap Protein.

Female BALB/c mice were immunized with a commercial PCV2 vaccine, and a monoclonal antibody (MAb) designated as 3H11 was achieved by hybridoma techniques. The MAb specifically reacted with Cap protein of PCV2, which has been identified by western blot. Immunoperoxidase monolayer assay results showed that 3H11 did not cross-react with PCV1-infected cells.

Canine distemper virus isolated from a monkey efficiently replicates on Vero cells expressing non-human primate SLAM receptors but not human SLAM receptor.

Background: In 2008, an outbreak of canine distemper virus (CDV) infection in monkeys was reported in China. We isolated CDV strain (subsequently named Monkey-BJ01-DV) from lung tissue obtained from a rhesus monkey that died in this outbreak. We evaluated the ability of this virus on Vero cells expressing SLAM receptors from dog, monkey and human origin, and analyzed the H gene of Monkey-BJ01-DV with other strains.

Large-scale production of foot-and-mouth disease virus (serotype Asia1) VLP vaccine in Escherichia coli and protection potency evaluation in cattle.

Background: Foot-and-mouth disease (FMD) is an acute, highly contagious disease that infects cloven-hoofed animals. Vaccination is an effective means of preventing and controlling FMD. Compared to conventional inactivated FMDV vaccines, the format of FMDV virus-like particles (VLPs) as a non-replicating particulate vaccine candidate is a promising alternative.

Fatal canine distemper virus infection of giant pandas in China.

We report an outbreak of canine distemper virus (CDV) infection among endangered giant pandas (Ailuropoda melanoleuca). Five of six CDV infected giant pandas died. The surviving giant panda was previously vaccinated against CDV.

Outbreak Investigation of NADC30-Like PRRSV in South-East China.

Epidemiological outbreak investigations were conducted on NADC30-like porcine reproductive and respiratory syndrome virus (PRRSV) to investigate the prevalence of the disease in south-east China in 2015. Two more provinces were found to have NADC30-like PRRSV circulating besides previously reported six provinces. Phylogenetic analysis showed that these virus isolates were clustered in an independent branch and shared high nucleotide similarity to NADC30, a type 2 PRRSV that has been isolated in Unite States in 2008.

Remarkable preservation of Ca(2+) homeostasis and inhibition of apoptosis contribute to anti-muscle atrophy effect in hibernating Daurian ground squirrels.

The underlying mechanisms that hibernators deviated from muscle atrophy during prolonged hibernating inactivity remain elusive. This study tested the hypothesis that the maintenance of intracellular Ca(2+) homeostasis and inhibition of apoptosis would be responsible for preventing muscle atrophy in hibernating Daurian ground squirrels. The results showed that intracellular Ca(2+) homeostasis was maintained in soleus and extensor digitorum longus (EDL) in hibernation and post-hibernation, while cytosolic Ca(2+) was overloaded in gastrocnemius (GAS) in hibernation with a recovery in post-hibernation.

Complete Genome Sequence of a Classical Swine Fever Virus Isolate Belonging to New Subgenotype 2.1d from Henan Province, Central China.

We report here the complete genome sequence of HeN1505, a field isolate of classical swine fever virus belonging to the new subgenotype 2.1d. HeN1505 distinguishes itself from other classical swine fever virus (CSFVs) by 1 amino acid substitution in position 159 (threonine by isoleucine), which led to the loss of one N-glycosylation site in the N(pro) protein.

Complete Genome Sequence of an NADC30-Like Porcine Reproductive and Respiratory Syndrome Virus Characterized by Recombination with Other Strains.

We report here the complete genome sequence of an NADC30-like porcine reproductive and respiratory syndrome virus (PRRSV), HNyc15, which was characterized by recombination with VR-2332 and CH-1a PRRSV strains in open reading frames (ORFs) 2 to 4.

Pathogenicity comparison between highly pathogenic and NADC30-like porcine reproductive and respiratory syndrome virus.

The pathogenicity of HNjz15, an NADC30-like strain of porcine reproductive and respiratory syndrome virus (PRRSV), was investigated and compared to that of a highly pathogenic PRRSV JAX1 strain. Six-week-old pigs infected with each virus showed typical clinical symptoms, including high fever and respiratory disorders. Pigs infected with JXA1 had more-severe clinical manifestations than pigs infected with HNjz15.

Complete Genome Sequence of an NADC30-Like Strain of Porcine Reproductive and Respiratory Syndrome Virus in China.

The most recently emergent porcine reproductive and respiratory syndrome virus strains in China are characterized by 393 nucleotide deletions in the nonstructural protein 2 (NSP2) region and are known as NADC30-like strains. Here, we report the complete genome sequence of the NADC30-like HNjz15 strain that was isolated in 2015.

Complete Genome Sequence of a Variant Pseudorabies Virus Strain Isolated in Central China.

Pseudorabies virus (PRV) variants have been prevalent in China since 2011 and have caused huge economic losses to the Chinese pig industry. Here, we report the genome sequence of a PRV variant HN1201 that was isolated from diseased animals in central China in 2011.

Production of Escherichia coli-based virus-like particle vaccine against porcine circovirus type 2 challenge in piglets: Structure characterization and protective efficacy validation.

We report the strategies leading to the large-production of soluble non-tag full-length porcine circovirus type 2 (PCV2) Cap protein in Escherichia coli. Under neutral pH condition, the purified recombinant Cap protein derived from E. coli expression self-assembles into homogenous round virus-like particle at the similar size of that of the intact PCV2 virus, which is further characterized by Cryo-EM single particle structure determined at 4.

Complete Genome Sequence of a Chinese Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus That Has a Further Deletion in the Nsp2 Gene.

Here, we report the complete genome of a Chinese highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) characterized by a further 29-amino acid (87 nucleotides) deletion in its Nsp2-coding region compared to the prototype of the HP-PRRSV JXA1 strain.

Pathogenicity of a currently circulating Chinese variant pseudorabies virus in pigs.

Aim: To test the pathogenicity of pseudorabies virus (PRV) variant HN1201 and compare its pathogenicity with a classical PRV Fa strain.

Methods: The pathogenicity of the newly-emerging PRV variant HN1201 was evaluated by different inoculating routes, virus loads, and ages of pigs. The classical PRV Fa strain was then used to compare with HN1201 to determine pathogenicity.

Development of a Neutralizing Monoclonal Antibody Against Porcine Epidemic Diarrhea Virus S1 Protein.

The truncated spike protein (S1, 390-789aa) of porcine epidemic diarrhea virus was expressed as a recombinant protein in Baculorvirus expression system. Female BALB/c mice were immunized with the purified recombinant S1 (rS1) protein and two monoclonal antibodies, designated 8A3A10 and 12C4G12, were generated by hybridoma technique. The two monoclonal antibodies specifically reacted with PEDV rS1 protein, as proven by Western blot and indirect immunofluorescence assay.

Complete genomic characterization and genetic diversity of four European genotype porcine reproductive and respiratory syndrome virus isolates from China in 2011.

Porcine reproductive and respiratory syndrome (PRRS) is an emerging disease that has caused serious economic losses to the swine industry worldwide. In 2011, a nation-wide surveillance program investigated the prevalence of PRRS viruses (PRRSV) in Chinese breeding swine farms, and four European genotype PRRSV (PRRSV-Type 1) were successfully isolated. To explore the genetic diversity of PRRSV-Type 1 in China, these 4 viral strains were subjected to genome sequencing and analysis.

Construction of a gE-Deleted Pseudorabies Virus and Its Efficacy to the New-Emerging Variant PRV Challenge in the Form of Killed Vaccine.

The new-emerging PRV variants plague the vaccinated pigs and caused huge economic loss to local pig industry in China since 2011. The current commercial PRV vaccines cannot provide complete protection as the new-emerging PRV variants are antigenically different from the classical viruses. It is urgent to develop more safe and effective PRV vaccines based on the current circulating field isolates.

The dynamics of Chinese variant porcine epidemic diarrhea virus production in Vero cells and intestines of 2-day old piglets.

A severe porcine epidemic diarrhea (PED) epizootic has been affecting pigs of all ages that are characterized by high mortality among suckling piglets in China since late 2010, causing significant economic losses. Obtaining a current-circulating PEDV variant isolate that can grow efficiently in cell culture is prerequisite for the development of efficient vaccines. In this study, PEDV strain HN1303 was isolated successfully on Vero cells with supplemental trypsin, and the isolate has been serially propagated in cell culture for over 95 passages.

Construction of a triple gene-deleted Chinese Pseudorabies virus variant and its efficacy study as a vaccine candidate on suckling piglets.

New-emerging variants of Pseudorabies virus (PRV) compromise the protection provided by current vaccines and cause the death of all ages of vaccinated pigs since 2011. New vaccines based on current circulating PRV strain are needed to control the spread of disease since the variants are antigenically different from classical strains of virus. In this study, a TK/gE/gI triple gene-deleted PRV derived from current circulating field isolate was generated by using bacterial artificial chromosome techniques, and the rescued virus showed similar growth properties in vitro to its parent strain but reduced plaque size.

Assessment of the safety and efficacy of an attenuated live vaccine based on highly pathogenic porcine reproductive and respiratory syndrome virus.

The safety and efficacy of the JXA1-R vaccine, an attenuated strain of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV), were examined using an intramuscular challenge model in piglets. The JXA1-R vaccine was obtained by passing HP-PRRSV JXA1 through Marc-145 cells (82nd passage). Genomic sequence comparisons showed that strain JXA1-R and its parental strain, JXA1, differ by 47 amino acids, and most of these differences are scattered throughout the PRRSV genome.

Deletion of the znuA virulence factor attenuates Actinobacillus pleuropneumoniae and confers protection against homologous or heterologous strain challenge.

The znuA gene is known to be important for growth and survival in Escherichia coli, Haemophilus spp., Neisseria gonorrhoeae, and Pasteurella multocida under low Zn(2+) conditions. This gene is also present in Actinobacillus pleuropneumoniae serotype 1; therefore, the aim of this study was to investigate the existence of a similar role for the znuA gene in the growth and virulence of this organism.

RNAi-based inhibition of porcine reproductive and respiratory syndrome virus replication in transgenic pigs.

Porcine reproductive and respiratory syndrome (PRRS) is an economically devastating viral disease causing heavy losses to the swine industry worldwide. Many studies have shown that transient delivery of small interfering RNA (siRNA) or adenovirus-mediated RNA interfere (RNAi) could potentially inhibit porcine reproductive and respiratory syndrome virus (PRRSV) replication in vivo and in vitro. Here, we applied RNAi to produce transgenic (TG) pigs that constitutively expressed PRRSV-specific siRNA derived from small hairpin RNA (shRNA).