Adenovirus-vectored shRNAs targeted to the highly conserved regions of VP1 and 2B in tandem inhibits replication of foot-and-mouth disease virus both in vitro and in vivo

Current and prospective control strategies of influenza A virus in swine

BACKGROUND

Influenza A Viruses (IAV) are endemic pathogens of significant concern in humans and multiple keystone livestock species. Widespread morbidity in swine herds negatively impacts animal welfare standards and economic performance whilst human IAV pandemics have emerged from pigs on multiple occasions. To combat the rising prevalence of swine IAV there must be effective control strategies available.

MAIN BODY

The most basic form of IAV control on swine farms is through good animal husbandry practices and high animal welfare standards. To control inter-herd transmission, biosecurity considerations such as quarantining of pigs and implementing robust health and safety systems for workers help to reduce the likelihood of swine IAV becoming endemic. Closely complementing the physical on-farm practices are IAV surveillance programs. Epidemiological data is critical in understanding regional distribution and variation to assist in determining an appropriate response to outbreaks and understanding the nature of historical swine IAV epidemics and zoonoses. Medical intervention in pigs is restricted to vaccination, a measure fraught with the intrinsic difficulties of mounting an immune response against a highly mutable virus. It is the best available tool for controlling IAV in swine but is far from being a perfect solution due to its unreliable efficacy and association with an enhanced respiratory disease. Because IAV generally has low mortality rates there is a reticence in the uptake of vaccination. Novel genetic technologies could be a complementary strategy for IAV control in pigs that confers broad-acting resistance. Transgenic pigs with IAV resistance are useful as models, however the complexity of these reaching the consumer market limits them to research models. More promising are gene-editing approaches to prevent viral exploitation of host proteins and modern vaccine technologies that surpass those currently available.

CONCLUSION

Using the suite of IAV control measures that are available for pigs effectively we can improve the economic productivity of pig farming whilst improving on-farm animal welfare standards and avoid facing the extensive social and financial costs of a pandemic. Fighting 'Flu in pigs will help mitigate the very real threat of a human pandemic emerging, increase security of the global food system and lead to healthier pigs.

Three kinds of treatment with Homoharringtonine, Hydroxychloroquine or shRNA and their combination against coronavirus PEDV in vitro

Background

Porcine epidemic diarrhea virus (PEDV) of the family Coronaviridae has caused substantial economic losses in the swine husbandry industry. There’s currently no specific drug available for treatment of coronaviruses or PEDV.

Method

In the current study, we use coronavirus PEDV as a model to study antiviral agents. Briefly, a fusion inhibitor tHR2, recombinant lentivirus-delivered shRNAs targeted to conserved M and N sequences, homoharringtonine (HHT), and hydroxychloroquine (HCQ) were surveyed for their antiviral effects.

Results

Treatment with HCQ at 50 μM and HHT at 150 nM reduced virus titer in TCID₅₀ by 30 and 3.5 fold respectively, and the combination reduced virus titer in TCID₅₀ by 200 fold.

Conclusion

Our report demonstrates that the combination of HHT and HCQ exhibited higher antiviral activity than either HHT or HCQ exhibited. The information may contribute to the development of antiviral strategies effective in controlling PEDV infection.

Silencing of the foot-and-mouth disease virus internal ribosomal entry site by targeting relatively conserved region among serotypes

Foot-and-mouth disease (FMD) is a host-restricted disease of cloven-hoofed animals, such as cattle and pigs. There are seven major serotypes of FMD virus that exhibit high antigenic variation, making vaccine strain selection difficult. However, there is an internal ribosomal entry site (IRES) element within the 5′ untranslated region of the FMD virus (FMDV) RNA genome that is relatively conserved among FMDV serotypes and could be used as a pan-serotype target for disease interventions. To determine the potential for targeting the IRES as promising drug target, we designed a short interfering RNA (siRNA) targeting a relatively conserved region in the FMDV-IRES. The siRNA affected FMDV-IRES expression but not the expression of the encephalomyocarditis virus or hepatitis C virus IRES. To evaluate the effects of siRNA-mediated silencing, we established cell lines expressing a bicistronic luciferase reporter plasmid, which contained an FMDV-IRES element between the Renilla and firefly luciferase genes. The designed siRNA inhibited FMDV-IRES-mediated translation in a concentration-dependent manner. In order to sustain this inhibitory effect, we designed a short hairpin RNA (shRNA)-expressing lentiviral vector. The results showed that the lenti-shRNA vector significantly suppressed FMDV-IRES activity for up to 2 weeks in cell culture. Thus, our findings in this study provided a basis for the development of effective pan-serotype FMDV inhibitors.

Biological Function and Application of Picornaviral 2B Protein: A New Target for Antiviral Drug Development

Picornaviruses are associated with acute and chronic diseases. The clinical manifestations of infections are often mild, but infections may also lead to respiratory symptoms, gastroenteritis, myocarditis, meningitis, hepatitis, and poliomyelitis, with serious impacts on human health and economic losses in animal husbandry. Thus far, research on picornaviruses has mainly focused on structural proteins such as VP1, whereas the non-structural protein 2B, which plays vital roles in the life cycle of the viruses and exhibits a viroporin or viroporin-like activity, has been overlooked. Viroporins are viral proteins containing at least one amphipathic α-helical structure, which oligomerizes to form transmembrane hydrophilic pores. In this review, we mainly summarize recent research data on the viroporin or viroporin-like activity of 2B proteins, which affects the biological function of the membrane, regulates cell death, and affects the host immune response. Considering these mechanisms, the potential application of the 2B protein as a candidate target for antiviral drug development is discussed, along with research challenges and prospects toward realizing a novel treatment strategy for picornavirus infections.

Host microRNA-203a Is antagonistic to the progression of foot-and-mouth disease virus infection

Sam68 was previously shown to be a critical host factor for foot-and-mouth disease virus (FMDV) replication. MicroRNA (miR) miR-203a is reportedly a negative regulator of Sam68 expression both in vitro and in vivo. Here, transfection of miR-203a-3p and miR-203a-5p mimics separately and in combination in a porcine cell line followed by FMDV infection resulted in diminished viral protein synthesis and a 4 and 6log reduction in virus titers relative to negative controls, respectively. Unexpectedly, Sam68 expression was increased by miR-203a-5p transfection, but not miR-203a-3p. miR-203a-5p also down-regulated Survivin expression, which was predicted to play a role in FMDV infection. Moreover, miR-203a-5p but not miR-203a-3p affected a reduction in FMDV viral RNA. These effects were not replicated with a related Picornavirus, suggesting FMDV specificity. Importantly, miR-203a-3p and miR-203a-5p impaired FMDV infection across multiple FMDV serotypes. We concluded that miR-203a-3p and miR-203a-5p represent attractive potential naturally occurring bio-therapeutics against FMDV.

RNA interference-based technology: what role in animal agriculture?

Animal agriculture faces a broad array of challenges, ranging from disease threats to adverse environmental conditions, while attempting to increase productivity using fewer resources. RNA interference (RNAi) is a biological phenomenon with the potential to provide novel solutions to some of these challenges. Discovered just 20 years ago, the mechanisms underlying RNAi are now well described in plants and animals. Intracellular double-stranded RNA triggers a conserved response that leads to cleavage and degradation of complementary mRNA strands, thereby preventing production of the corresponding protein product. RNAi can be naturally induced by expression of endogenous microRNA, which are critical in the regulation of protein synthesis, providing a mechanism for rapid adaptation of physiological function. This endogenous pathway can be co-opted for targeted RNAi either through delivery of exogenous small interfering RNA (siRNA) into target cells or by transgenic expression of short hairpin RNA (shRNA). Potentially valuable RNAi targets for livestock include endogenous genes such as developmental regulators, transcripts involved in adaptations to new physiological states, immune response mediators, and also exogenous genes such as those encoded by viruses. RNAi approaches have shown promise in cell culture and rodent models as well as some livestock studies, but technical and market barriers still need to be addressed before commercial applications of RNAi in animal agriculture can be realised. Key challenges for exogenous delivery of siRNA include appropriate formulation for physical delivery, internal transport and eventual cellular uptake of the siRNA; additionally, rigorous safety and residue studies in target species will be necessary for siRNA delivery nanoparticles currently under evaluation. However, genomic incorporation of shRNA can overcome these issues, but optimal promoters to drive shRNA expression are needed, and genetic engineering may attract more resistance from consumers than the use of exogenous siRNA. Despite these hurdles, the convergence of greater understanding of RNAi mechanisms, detailed descriptions of regulatory processes in animal development and disease, and breakthroughs in synthetic chemistry and genome engineering has created exciting possibilities for using RNAi to enhance the sustainability of animal agriculture.

Registro do uso de antimicrobianos em Instituições de Longa Permanência para Idosos

Resumo Objetivo: Verificar o registro da prescrição e da utilização de antimicrobianos em Instituições de Longa Permanência para Idosos (ILPI), em municípios do Centro-Oeste de Minas Gerais. Método: Tratou-se de uma coorte retrospectiva, realizada em seis ILPIs filantrópicas. Utilizou-se um questionário contendo variáveis relacionadas aos dados sociodemográficos e de saúde, e registros de antimicrobianos. Empregou-se o teste Qui-quadrado de Pearson ou teste Exato de Fisher para avaliar a associação entre as variáveis. Resultados: Avaliaram-se os registros de 250 idosos. Dentre estes, 110 idosos fizeram uso de antimicrobianos. Houve associação entre tempo de permanência na instituição, o uso de antimicrobiano e o diagnóstico de infecção (p<0,05). Conclusão: A escassez e/ou inadequações quanto aos registros/prescrições de antimicrobianos e de infecções representa um problema para a saúde dos idosos podendo também comprometer a assistência por outros profissionais.

Tongue Epithelium Cells from shRNA Mediated Transgenic Goat Show High Resistance to Foot and Mouth Disease Virus

Foot and mouth disease induced by foot and mouth disease virus (FMDV) is severe threat to cloven-hoofed domestic animals. The gene 3Dpol in FMDV genome encodes the viral RNA polymerase, a vital element for FMDV replication. In this study, a conserved 3D-7414shRNA targeting FMDV-3Dpol gene was designed and injected into pronuclear embryos to produce the transgenic goats. Sixty-one goats were produced, of which, seven goats positively integrated 3D-7414shRNA. Loss of function assay demonstrated that siRNA effectively knockdown 3Dpol gene in skin epithelium cells of transgenic goats. Subsequently, the tongue epithelium cells from transgenic and non-transgenic goats were infected with FMDV O/YS/CHA/05 strain. A significant decrease of virus titres and virus copy number was observed in cells of transgenic goats compared with that of non-transgenic goats, which indicated that 3D-7414siRNA inhibited FMDV replication by interfering FMDV-3Dpol gene. Furthermore, we found that expression of TLR7, RIG-I and TRAF6 was lower in FMDV infected cells from transgenic goats compared to that from non-transgenic goats, which might result from lower virus copy number in transgenic goats’ cells. In conclusion, we successfully produced transgenic goats highly expressing 3D-7414siRNA targeting 3Dpol gene, and the tongue epithelium cells from the transgenic goats showed effective resistance to FMDV.

Effective inhibition of porcine epidemic diarrhea virus by RNA interference in vitro

Porcine epidemic diarrhea virus (PEDV) is a member of the coronaviridae family, which can cause acute and highly contagious enteric disease of swine characterized by severe entero-pathogenic diarrhea in piglets. Currently, the vaccines of PEDV are only partially effective and there is no specific drug available for treatment of PEDV infection. To exploit the possibility of using RNA interference (RNAi) as a strategy against PEDV infection, five shRNA-expressing plasmids targeting the N, M, and S genes of PEDV were constructed and transfected into Vero cells. The cytopathic effect and MTS assays demonstrated that two shRNAs (pSilencer4.1-M1 and pSilencer4.1-N) were capable of protecting cells against PEDV invasion with very high specificity and efficiency. The two shRNA expression plasmids were also able to inhibit the PEDV replication significantly, as shown by detection of virus titers (TCID50/mL). A real-time quantitative RT-PCR further confirmed that the amounts of viral RNAs in cell cultures pre-transfected with these two plasmids were reduced by 95.0 %. Our results suggest that RNAi might be a promising new strategy against PEDV infection.

Development of sheep kidney cells with increased resistance to different subgenotypes of BVDV-1 by RNA interference

Bovine viral diarrhea virus (BVDV) should be a ubiquitous viral pathogen to the cattle and sheep industry. This pathogen is responsible for severe economic losses. We previously showed that plasmid-mediated dual short hairpin RNA (shRNA) efficiently inhibit BVDV replication in bovine kidney epithelial (MDBK) cells. In this study, we delivered the dual shRNA system to sheep fibroblasts and generated transgenic cell colonies. These transgenic fibroblasts were further used for somatic cell nuclear transfer (SCNT). Three lambs were born at full term, but perished soon after birth. Integration of shRNA into the genome of cloned sheep was confirmed by PCR and expression of shRNA in transgenic sheep was confirmed by real-time PCR. Kidney epithelial cells were isolated from transgenic sheep and challenged with multiple BVDV subgenotypes (BVDV-1a, BVDV-1b and BVDV-1c). The dual shRNA expressed in transgenic kidney epithelial cells significantly inhibited BVDV replication in a cross-resistance manner. Our results showed that transgenic RNAi might be a useful tool for preparation of transgenic animals with increased resistance to BVDV.