Transmissible Gastroenteritis Viruses Research Articles

Porcine respiratory coronavirus genome sequences; comparisons and relationships to transmissible gastroenteritis viruses

Porcine respiratory coronavirus (PRCV) was initially detected in Europe, and later in the United States of America (US), in the 1980s. In this study we obtained and compared PRCV sequences from Europe and the US, and investigated how these are related to transmissible gastroenteritis virus (TGEV) sequences.The whole genome sequences of Danish (1/90-DK), Italian (PRCV15087/12 III NPTV Parma), and Belgian PRCV (91V44) strains are presented. These sequences were aligned with nine other PRCV sequences from Europe and the US, and 43 TGEV sequences. Following alignment of the PRCV sequences, it was apparent that multiple amino acid variations in the structural proteins were distinct between the European and US strains. The alignments were used to build phylogenetic trees to infer the evolutionary relationships between the strains. In these trees, the European PRCV strains clustered as a separate group, whereas the US strains of PRCV all clustered with TGEVs.

First isolation and whole genome characterization of porcine deltacoronavirus from pigs in Peru.

Porcine deltacoronavirus is a newly emergent enteric pathogen affecting swine farms worldwide. It has been detected in several countries in Europe, Asia and North America; yet, it has not been reported in South America. In November 2019, an enteric disease outbreak in a pig farm located in San Martin, Peru, was reported along with submission of three intestinal samples from pigs who succumbed to the disease. Samples were processed for molecular detection by qRT-PCR, viral isolation and further sequencing analysis. A taqman-based RT-PCR was performed to differentiate among the most relevant swine enteric coronaviruses described to date. All samples were positive to porcine deltacoronavirus with a cycle threshold (Ct) value between 9 and 14, revealing a high viral load, while testing negative to porcine epidemic diarrhea and transmissible gastroenteritis viruses. Following detection, viral isolation was performed using PK-15 and Vero cell lines. After 5 days of inoculation, no cytopathic effect was observed. A second blind passage allowed the observation of cytopathic effect on PK-15 cells, while it remained absent in Vero cells. A fluorescence test using an anti-N monoclonal antibody confirmed viral replication. One sample was processed for whole genome sequencing (WGS). In short, raw reads were imported into CLC genomics and assembled de novo. Out of 479k reads generated from the sample, 436k assembled into a 25,501bp contig which was 99.5% identical to a reference porcine deltacoronavirus strain from the USA within the North American phylogroup. Yet, there are relevant differences at the nucleotide and amino acid levels compared with previously described porcine deltacoronavirus strains. Altogether, our findings represent the first report of porcine deltacoronavirus in South America, which provides information of its evolutionary origin. Thus, this study offers new insights into the molecular epidemiology of porcine deltacoronavirus infections in the swine industry.

The most eagerly awaited summer of the Anthropocene: A perspective of SARS-CoV-2 decay and seasonal change

To date, the world perhaps has never waited for the summer so impatiently in the entire Anthropocene, owing to the debate whether increasing temperature and humidity will decrease the environmental endurance of SARS-CoV-2. We present the perspective on the seasonal change on SARS-CoV-2 decay and COVID-19 spread. Our arguments are based on: i) structural similarity of coronavirus with several enteric viruses, and its vulnerability; ii) reports related to decay of those similar transmissible gastroenteritis viruses (TGEV) like norovirus and iii) improvement in the human immunity during summer compared to winter. We present reasons why we can be optimistic about the slowdown of corona in the upcoming summer.

Antiviral Activity of Lauryl Gallate against Animal Viruses

Background Antiviral compounds are needed in the control of many animal and human diseases. Methods We analysed the effect of the antitumoural drug lauryl gallate on the infectivity of the African swine fever virus among other DNA (herpes simplex and vaccinia) and RNA (influenza, porcine transmissible gastroenteritis and Sindbis) viruses, paying attention to its effect on the viability of the corresponding host cells. Results Viral production was strongly inhibited in different cell lines at non-toxic concentrations of the drug (1–10 μM), reducing the titres 3–>5 log units depending on the multiplicity of infection. In our model system (African swine fever virus in Vero cells), the addition of the drug 1 h before virus adsorption completely abolished virus productivity in a one-step growth virus cycle. Interestingly, no inhibitory effect was observed when lauryl gallate was added after 5–8 h post-infection. Both cellular and viral DNA synthesis and late viral transcription were inhibited by the drug; however, the early viral protein synthesis and the virus-mediated increase of p53 remained unaffected. Activation of the apoptotic effector caspase-3 was not detected after lauryl gallate treatment of Vero cells. Furthermore, the presence of the drug abrogated the activation of this protease induced by the virus infection. Conclusions Lauryl gallate is a powerful antiviral agent against several pathogens of clinical and veterinary importance. The overall results indicate that a cellular factor or function might be the target of the antiviral action of alkyl gallates.

Sequence analysis of the ORF 7 region of transmissible gastroenteritis viruses isolated in Korea

Three (KT2, 133, and DAE) transmissible gastroenteritis viruses (TGEVs) were isolated from pigs suspected of having TGE in Korea. One, KT2 (KT2-L), was passaged 128 times (KT2-H) in swine testicular cells. The open reading frame 7 (ORF 7) gene from each of the four TGEVs (KT2-L, KT2-H, 133, and DAE), which is located at the 3' end of the TGEV genome, was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). Amplified PCR products were cloned, sequenced, and compared with published sequences of non-Korean TGEV strains. Differences in replication and cytopathic effect (CPE) between the KT2-L and KT2-H strains in swine testicular cells were investigated. Korean TGEV field strains had 94.8-99.6% nucleotide and 92.1-98.7% amino acid sequence similarity with each other, and 87.8-100.0% nucleotide and 84.2-100.0% amino acid sequence similarity with non-Korean TGEV strains. Compared to the original KT2-L strain, the KT2-H strain differed by 2.2 and 3.9% in nucleotide and amino acid sequences, respectively. Specifically, the KT2-H had six nucleotide and two amino acid deletions compared to the original KT2-L strain. In phylogenetic analysis of the ORF 7 gene, Korean TGEV strains were clustered into two groups. One group (KT2-L, KT2-H, 133) was related to TGEV strains isolated in Japan. Another Korean TGEV isolate (DAE) was related to a strain from China and one from the USA. The Korean TGEV isolates appear to have evolved from a separate lineage of TGEV strain. Differences in growth rate and CPE between the KT2-L and KT2-H strains were discovered in swine testicular cells (STCs). The KT2-H strain exhibited a higher replication rate than KT2-L and produced a CPE distinctly different from that of the KT2-L strain.

Antiviral activity of lauryl gallate against animal viruses.

Antiviral compounds are needed in the control of many animal and human diseases. We analysed the effect of the antitumoural drug lauryl gallate on the infectivity of the African swine fever virus among other DNA (herpes simplex and vaccinia) and RNA (influenza, porcine transmissible gastroenteritis and Sindbis) viruses, paying attention to its effect on the viability of the corresponding host cells. Viral production was strongly inhibited in different cell lines at non-toxic concentrations of the drug (1-10 microM), reducing the titres 3->5 log units depending on the multiplicity of infection. In our model system (African swine fever virus in Vero cells), the addition of the drug 1 h before virus adsorption completely abolished virus productivity in a one-step growth virus cycle. Interestingly, no inhibitory effect was observed when lauryl gallate was added after 5-8 h post-infection. Both cellular and viral DNA synthesis and late viral transcription were inhibited by the drug; however, the early viral protein synthesis and the virus-mediated increase of p53 remained unaffected. Activation of the apoptotic effector caspase-3 was not detected after lauryl gallate treatment of Vero cells. Furthermore, the presence of the drug abrogated the activation of this protease induced by the virus infection. Lauryl gallate is a powerful antiviral agent against several pathogens of clinical and veterinary importance. The overall results indicate that a cellular factor or function might be the target of the antiviral action of alkyl gallates.

Partial sequence of the spike glycoprotein gene of transmissible gastroenteritis viruses isolated in Korea

The spike (S) glycoprotein of transmissible gastroenteritis virus (TGEV) is the predominant inducer of neutralizing antibodies and has been implicated in virulence and host cell tropism. In this study, the nucleotide and deduced amino acid sequences of the amino terminal half of the S glycoprotein gene of one Korean field TGEV strain (133) isolated in 1997 and three Korean field TGEV strains (KT2, KT3 and KT4) isolated in 2000 and HKT2 strain, KT2 passaged 104 times in ST cells, were determined. The amino terminal half of the S glycoprotein gene including antigenic sites A, B, C and D, were amplified by reverse transcriptase-polymerase chain reaction (RT-PCR). Amplified PCR products were cloned, sequenced, and compared with published sequences for non-Korean TGEV strains. Korea TGEV field strains had 98.5–99.5% nucleotide sequence and 97.2–99.0% amino acid sequence similarity with each other. They had 96.5–99.0% nucleotide sequence similarity and 94.9–97.6% amino acid sequence similarity compared to non-Korean TGEV strains. Korean TGEV strains had several specific nucleotide and amino acid sequences which were not found in foreign TGEV or PRCV strains. HKT2 strain differed by 0.89% in nucleotide and 2.03% amino acid sequences compared to original KT2 strain although the regions forming four antigenic sites were not changed. By phylogenetic tree analysis, Korean field TGEV strains were branched into different groups from non-Korean TGEV or PRCV strains. Korean TGEV field strains KT2 and 133 were branched in separate groups that were differentiated from the other Korean TGEV strains. The Korean TGEV strains seemed to be evolved from a separate lineage of TGEV strain.

The multiplication of transmissible gastroenteritis viruses in several cell lines originated from porcine kidney and effects of trypsin on the growth of the viruses.

Plaque formation, replication and related cytopathic function of 9 strains of transmissible gastroenteritis (TGE) virus were examined in primary cells and cell lines such as CPK, IB-RS-2, ESK, and PK-15 originated from porcine kidney and the effects of trypsin on the replication of TGE virus were examined in CPK cells. All strains produced a cytopathic effect and grew well in CPK cells as well as in primary porcine kidney cells. The effect of trypsin on the plaque formation was different from strains. The number of plaques produced by strains TO-163, Ukiha and Niigata increased from 2.6 to 3.52 times when trypsin was present in the medium during incubation at 37 degrees C for 1 hr after adsorption of the virus at 4 degrees C for 2 hr. The plaque sizes of TO-163, h-5, Ukiha and Niigata became larger from 1.4 to 1.7 times, when trypsin was present in the agar MEM overlay.

Characteristics of the porcine kidney cell line IB-RS-2 clone D10 (IB-RS-2 D10) which is free of hog cholera virus.

A Brazilian stock of clone C17 of the IB-RS-2 porcine kidney cell line which was contaminated with hog cholera virus (HCV) was cloned. One clone designated IB-RS-2 D10 was determined to be free of HCV, 20 other viruses, and Mycoplasma. IB-RS-2 D10 cells possessed the same viral susceptibility pattern as the contaminated parent cells to the viruses of foot-and-mouth disease, swine vesicular disease, vesicular exanthema of swine, transmissible gastroenteritis, and several other viruses. The IB-RS-2 D10 cells had a median chromosome count of 34, were morphologically epithelioid cells, and were resistant to HCV infection. Freedom from HCV affords advantages for vaccine production and avoids laboratory contamination.

Cross-protection studies between feline infectious peritonitis and porcine transmissible gastroenteritis viruses

Cross-protection studies between the feline infectious peritonitis (FIP) and the porcine transmissible gastroenteritis (TGE) viruses were conducted in cats, pigs and pregnant gilts. Cats vaccinated with TGE virus developed neutralizing antibodies against TGE virus and low titer antibody against FIP virus detected by an indirect fluorescent antibody technique but were not protected against a virulent FIP virus challenge. Baby pigs and pregnant gilts vaccinated with FIP virus did not develop detectable antibodies to TGE virus. Nevertheless, it appeared that vaccination of swine with FIP virus conferred some immunity against TGE virus infection. Seventeen-day-old pigs vaccinated with two doses of FIP virus had a 67% survival rate following a virulent TGE virus challenge, and 75% of the 3-day-old pigs suckling either FIP or TGE-virus-vaccinated gilts survived virulent TGE virus infection in contrast to 0% survival of baby pigs suckling unvaccinated gilts.

Isoprinosine: lack of antiviral activity in experimental model infections.

This report is a condensation of data from a collaborative study proposed and sponsored by the Antiviral Substances Program of NIAID. The individual reports were prepared by the following persons: S. Baron and M. Worthington, NIAID, NIH; A. Friedman-Kien, New York University College of Medicine; J. C. Duenwald, Washington State University, L. A. Glasgow, M. Harmon, B. Janis, E. Kern, J. C. Overall, Jr., C. B. Smith, D. A. Stringfellow, and S. Westerberg, University of Utah College of Medicine; B. C. Easterday and E. H. Weinberg, University of Wisconsin.*Recently there has been much interest in isoprinosine as a broad-spectrum antiviral compound. The activity of this substance was evaluated in a coordinated study at five institutions. Experimental models in five species of animals were established using 11 viruses. Criteria for selection were: (l) representation of most major groups of viruses, (2) reproduction of natural routes of infection, and (3) simulation of potentially treatable viral infections of man. No therapeutic effect could be demonstrated in infections with encephalomyocarditis virus, type 2 Herpesvirus hominis, influenza, and rabies viruses in mice; vaccinia virus in rabbits; rhinotracheitis and panleukopenia viruses in cats; distemper virus in ferrets; and influenza and transmissible gastroenteritis viruses in swine. The only antiviral activity observed in this extensive series of experiments was suppression of fibroma virus lesions in rabbits given 600 mg/ kg per day of isoprinosine. Although antiviral activity is not precluded in other viral infections in animals or in man, these results clearly fail to substantiate the potential of isoprinosine as a potent, broad-spectrum antiviral substance.