Broadening the heterologous cross-neutralizing antibody inducing ability of porcine reproductive and respiratory syndrome virus by breeding the GP4 or M genes.

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important swine pathogens, which causes reproductive failure in sows and respiratory disease in piglets. A major hurdle to control PRRSV is the ineffectiveness of the current vaccines to confer protection against heterologous strains. Since both GP4 and M genes of PRRSV induce neutralizing antibodies, in this study we molecularly bred PRRSV through DNA shuffling of the GP4 and M genes, separately, from six genetically different strains of PRRSV in an attempt to identify chimeras with improved heterologous cross-neutralizing capability.

DNA shuffling of the GP3 genes of porcine reproductive and respiratory syndrome virus (PRRSV) produces a chimeric virus with an improved cross-neutralizing ability against a heterologous PRRSV strain.

Porcine reproductive and respiratory syndrome virus (PRRSV) is an important swine pathogen. Here we applied the DNA shuffling approaches to molecularly breed the PRRSV GP3 gene, a neutralizing antibodies inducer, in an attempt to improve its heterologous cross-neutralizing ability. The GP3 genes of six different PRRSV strains were bred by traditional DNA shuffling.

Assessment of the cross-protective capability of recombinant capsid proteins derived from pig, rat, and avian hepatitis E viruses (HEV) against challenge with a genotype 3 HEV in pigs.

Hepatitis E virus (HEV), the causative agent of hepatitis E, is primarily transmitted via the fecal-oral route through contaminated water supplies, although many sporadic cases of hepatitis E are transmitted zoonotically via direct contact with infected animals or consumption of contaminated animal meats. Genotypes 3 and 4 HEV are zoonotic and infect humans and other animal species, whereas genotypes 1 and 2 HEV are restricted to humans. There exists a single serotype of HEV, although the cross-protective ability among the animal HEV strains is unknown.

Rescue of a genotype 4 human hepatitis E virus from cloned cDNA and characterization of intergenotypic chimeric viruses in cultured human liver cells and in pigs.

Hepatitis E virus (HEV) is an important but extremely understudied human pathogen. Genotypes 1 and 2 are restricted to humans, whereas genotypes 3 and 4 are zoonotic, infecting both humans and pigs. This report describes, for the first time, the successful rescue of infectious HEV in vitro and in vivo from cloned cDNA of a genotype 4 human HEV (strain TW6196E).

Serological profile of torque teno sus virus species 1 (TTSuV1) in pigs and antigenic relationships between two TTSuV1 genotypes (1a and 1b), between two species (TTSuV1 and -2), and between porcine and human anelloviruses.

The family Anelloviridae includes human and animal torque teno viruses (TTVs) with extensive genetic diversity. The antigenic diversity among anelloviruses has never been assessed. Using torque teno sus virus (TTSuV) as a model, we describe here the first investigation of the antigenic relationships among different anelloviruses.

Cross-species infection of pigs with a novel rabbit, but not rat, strain of hepatitis E virus isolated in the United States.

Hepatitis E virus (HEV) is an important human pathogen. In addition to humans, HEV has also been identified in pig, chicken, mongoose, deer, rat, rabbit and fish. There are four recognized and two putative genotypes of mammalian HEV.

Rescue of a porcine anellovirus (torque teno sus virus 2) from cloned genomic DNA in pigs.

Anelloviruses are a group of single-stranded circular DNA viruses infecting humans and other animal species. Animal models combined with reverse genetic systems of anellovirus have not been developed. We report here the construction and initial characterization of full-length DNA clones of a porcine anellovirus, torque teno sus virus 2 (TTSuV2), in vitro and in vivo.

Immunogenicity study of plant-made oral subunit vaccine against porcine reproductive and respiratory syndrome virus (PRRSV).

Currently, killed-virus and modified-live PRRSV vaccines are used to control porcine reproductive and respiratory syndrome disease (PRRS). However, very limited efficacy of killed-virus vaccines and serious safety concerns for modified-live virus vaccines demand the development of novel PRRSV vaccines. In this report, we investigated the possibility of using transgenic plants as a cost-effective and scalable system for production and delivery of a viral protein as an oral subunit vaccine against PRRSV.

Hepatitis E virus in rabbits, Virginia, USA.

We identified hepatitis E virus (HEV) in rabbits in Virginia, USA. HEV RNA was detected in 14 (16%) of 85 serum samples and 13 (15%) of 85 fecal samples. Antibodies against HEV were detected in 31 (36%) of 85 serum samples.

Mutational analysis of the hypervariable region of hepatitis e virus reveals its involvement in the efficiency of viral RNA replication.

The RNA genome of the hepatitis E virus (HEV) contains a hypervariable region (HVR) in ORF1 that tolerates small deletions with respect to infectivity. To further investigate the role of the HVR in HEV replication, we constructed a panel of mutants with overlapping deletions in the N-terminal, central, and C-terminal regions of the HVR by using a genotype 1 human HEV luciferase replicon and analyzed the effects of deletions on viral RNA replication in Huh7 cells. We found that the replication levels of the HVR deletion mutants were markedly reduced in Huh7 cells, suggesting a role of the HVR in viral replication efficiency.

Prior infection of pigs with a genotype 3 swine hepatitis E virus (HEV) protects against subsequent challenges with homologous and heterologous genotypes 3 and 4 human HEV.

Hepatitis E virus (HEV) is an important human pathogen. At least four recognized and two putative genotypes of mammalian HEV have been reported: genotypes 1 and 2 are restricted to humans whereas genotypes 3 and 4 are zoonotic. The current experimental vaccines are all based on a single strain of HEV, even though multiple genotypes of HEV are co-circulating in some countries and thus an individual may be exposed to more than one genotype.

Intergenotypic chimeric hepatitis E viruses (HEVs) with the genotype 4 human HEV capsid gene in the backbone of genotype 3 swine HEV are infectious in pigs.

Genotypes 1 and 2 hepatitis E virus (HEV) infect only humans whereas genotypes 3 and 4 HEV infect both humans and pigs. To evaluate the mechanism of cross-species HEV infection between humans and swine, in this study we constructed five intergenotypic chimeric viruses and tested for their infectivity in vitro and in pigs. We demonstrated that chimeric viruses containing the ORF2 capsid gene either alone or in combination with its adjacent 5' junction region (JR) and 3' noncoding region (NCR) from a genotype 4 human HEV in the backbone of a genotype 3 swine HEV are replication-competent in Huh7 cells and infectious in HepG2/C3A cells and in pigs, and thus supporting the hypothesis that genotypes 3 and 4 human HEV are of swine origin.

Construction of an infectious cDNA clone of avian hepatitis E virus (avian HEV) recovered from a clinically healthy chicken in the United States and characterization of its pathogenicity in specific-pathogen-free chickens.

A genetically distinct strain of avian hepatitis E virus (avian HEV-VA strain) was isolated from a healthy chicken in Virginia, and thus it is important to characterize and compare its pathogenicity with the prototype strain (avian HEV-prototype) isolated from a diseased chicken. Here we first constructed an infectious clone of the avian HEV-VA strain. Capped RNA transcripts from the avian HEV-VA clone were replication-competent after transfection of LMH chicken liver cells.

Purification of porcine reproductive and respiratory syndrome virus from cell culture using ultrafiltration and heparin affinity chromatography.

Porcine reproductive and respiratory syndrome (PRRS) virus is the causative agent of the most significant infectious disease currently affecting the swine industry worldwide. Density gradient ultracentrifugation remains the most commonly used method for porcine reproductive and respiratory syndrome virus (PRRSV) purification. However, this technique has notable drawbacks including long processing time and limited processing volume in each run.