Isolation, identification and characterization of a Peste des Petits Ruminants virus from an outbreak in Nanakpur, India

Evolution of drug resistance against antiviral agents that target cellular factors

Antiviral drugs have classically been developed by directly disrupting the functions of viral proteins. However, this strategy has been largely unsuccessful due to the rapid generation of viral escape mutants. It has been well established that as compared to the virus-centric approach, the strategy of developing antiviral drugs by targeting host-dependency factors (HDFs) minimizes drug resistance. However, recent reports have indicated that drug resistance against some of the host-targeting antiviral agents can in fact occur under some circumstances. Long-term selection pressure of a host-targeting antiviral agent may induce the virus to use an alternate cellular factor or alters its affinity towards the target that confers resistance. Alternatively, virus may synchronize its life cycle with the patterns of drug therapy. In addition, virus may subvert host's immune system to perpetuate under the limiting conditions of the targeted cellular factor. This review describes novel potential mechanisms that may account for the acquiring resistance against agents that target HDFs.

Molecular Characterization of Lineage-IV Peste Des Petits Ruminants Virus and the Development of In-House Indirect Enzyme-Linked Immunosorbent Assay (IELISA) for its Rapid Detection"

Peste des petits ruminants (PPRV), a highly contagious viral disease, causes significant economic losses concerning sheep and goats. Recently, PPR viruses (PPRVs), have adopted new hosts and lineage IV of PPRVs represents genetic diversity within the same lineage. 350 samples, including blood, swabs, and tissues from sheep/goats, were collected during the 2020-2021 disease outbreaks in Pakistan. These samples were analysed through RT-PCR and three isolates of PPRV with accession numbers, MW600920, MW600921, and MW600922, were submitted to GenBank, based on the partial N-gene sequencing. This analysis provides a better understanding of genetic characterizations and a targeted RT-PCR approach for rapid PPRV diagnosis. An IELISA test was developed using the semi-purified antigen MW600922 isolate grown in Vero cells. The PPRV isolates currently present high divergence with the Turkish strain; conversely, similarities equivalent to 99.73% were observed for isolates collected from Pakistan. The developed indirect ELISA (IELISA) test demonstrated antibody detection rates at dilutions of 1:200 for antibodies (serum) and 1:32 for antigens. In comparison to cELISA, high specificity (85.23%) and sensitivity (90.60%) rates were observed. In contrast to the virus neutralization test (VNT), IELISA was observed to be 100% specific and 82.14% sensitive in its results. Based on these results, serological surveys conducted for PPR antibodies using IELISA can be a more effective strategy on a larger scale. Furthermore, our results demonstrate a significant breakthrough in the research in terms of cost-effectiveness and storage efficiency, and the developed IELISA test is highly recommended for use in developing countries.

Development of Hemagglutinin-Neuraminidase Homologous Peptides as Novel Promising Therapeutic Agents Against Peste des Petits Ruminants Virus

The lack of specific antiviral therapy and complications associated with the existing peste des petits ruminants (PPR) vaccines accentuates the search of novel antiviral blocking agents in order to curtail the PPR infection at initial level. The synthetic hemagglutinin-neuraminidase (HN) homologous peptides may compete with the natural HN protein of PPR virus for binding to signaling lymphocytic activation molecule (SLAM) receptor, consequently, may disrupt peste des petits ruminants virus (PPRV) at entry level. Therefore, insilico analysis, synthesis, purification and subsequent characterization of HN homologous peptides were conducted in this study. The HN homologous peptides were synthesized by means of solid phase chemistry and were purified by reversed-phase-high performance liquid chromatography. The mass as well as sequence of HN homologous peptides were assessed by mass spectroscopy while its secondary structure was elucidated by circular dichroism spectroscopy. The binding (interaction) efficacy of HN homologous peptides with PPRV antibodies was assessed via indirect enzyme linked immunosorbent assay, visual detection test (red wine to purple), bathochromic shift under UV-Vis spectrophotometry and lateral flow immunochromatographic strip test. The antiviral properties and cytotoxicity of these peptides were also assessed in B95a cell line with changes in cytopathic effect and titer of PPRV (Sungri/96). The presence of green fluorescein isothiocyanate over the B95a cell surface pointed towards the binding of HN homologous peptides with surface SLAM receptor. Moreover, the intact beta sheet configuration in water and lower cytotoxicity [cytotoxic concentration 50 (CC50) > 1000 µg/ml] of these peptides signifies its in vivo use. Among HN homologous peptides, the binding efficacy and antiviral properties of pep A was relatively high in comparison to pep B and Pep ppr peptides. The prerequisite concentration of HN homologous peptides (pep A = 12.5 µg/ml; pep B = 25 µg/ml; pep ppr = 25 µg/ml) to exemplify its antiviral effect was much lower than its CC50 level. Hence, this study signifies the therapeutic potential of synthetic HN homologous peptides.

Peste des Petits Ruminants Virus Exhibits Cell-Dependent Interferon Active Response

Peste des petits ruminants (PPR) is an acute and highly pathogenic infectious disease caused by peste des petits ruminants virus (PPRV), which can infect goats and sheep and poses a major threat to the small ruminants industry. The innate immune response plays an important role as a line of defense against the virus. The effect of PPRV on the active innate immune response has been described in several studies, with different conclusions. We infected three goat-derived cell lines with PPRV and tested their innate immune response. PPRV proliferated in caprine endometrial epithelial cells (EECs), caprine skin fibroblasts cells (GSFs), and goat fibroblast cells (GFs), and all cells expressed interferon (IFN) by poly (I: C) stimulation. PPRV infection stimulated expression of type I and type III IFN on EECs, and expression of the latter was significantly stronger, but IFN was not stimulated in fibroblasts (GSFs and GFs). Our results suggested that the effect of PPRV on IFN was cell-type specific. Nine IFN-stimulated genes (ISGs) were detected in EECs, but only ISG15 and RSAD2 were significantly upregulated. The effects of PPRV on IFN and IFN-induced ISGs were cell-type specific, which advances our understanding of the innate immune response induced by PPRV and creates new possibilities for the control of PPRV infection.

Epigallocatechin gallate (EGCG) combined with zinc sulfate inhibits Peste des petits ruminants virus entry and replication

Despite the fact that the Peste des petits ruminants virus (PPRV) leads to high morbidity and mortality (up to 100%), antiviral drugs against PPRV are not available. The aim of this study was to estimate the dose of epigallocatechin gallate (EGCG) co-administered with zinc (II) ions as an antiviral agent against PPRV. Treatment of PPRV-infectedVero cells with EGCG and zinc sulfate (zinc II) was administered, and antiviral activities against PPRV in infected Vero cells was evaluated by determination of virus yields, expressed as logTCID50/mL. Cytotoxicity was determined using the tetrazolium-based MTS test. Zinc sulfate at 1.1 mg/mL and EGCG at 25 μM showed low potentiated and potentiated antiviral activities against PPRV, respectively. These agents caused significant inhibition of PPRV in Vero cells (p < 0.05) with a reduction in logTCID50/mL by up to 3-fold. The combination of EGCG (25 μM) and zinc sulfate (1.1 mg/mL) was observed to have strong antiviral activity (p < 0.01) against PPRV with a reduction in logTCID50/mL of the virus up to 4-times without causing any host cell cytotoxicity. This study is the first one to prove that the zinc II has the capability of stimulating EGCG to inhibit in vitro PPRV entry. Moreover, this combination appears capable of reducing infection resistance by hindering viral adaptation.

Nanoparticles as a novel and promising antiviral platform in veterinary medicine

Traditional veterinary virus vaccines, such as inactivated and live-attenuated vaccines, have achieved tremendous success in controlling many viral diseases of livestock and chickens worldwide. However, many recent viral outbreaks caused by different emerging and re-emerging viruses continue to be reported annually worldwide. It is therefore necessary to develop new control regimens. Nanoparticle research has received considerable attention in the last two decades as a promising platform with significant success in veterinary medicine, replacing traditional viral vector vaccines. However, the field of nanoparticle applications is still in its initial phase of growth. Here, we discuss various preparation methods, characteristics, physical properties, antiviral effects, and pharmacokinetics of well-developed nanoparticles and the potential of nanoparticles or nano-vaccines as a promising antiviral platform for veterinary medicine.

Prevalence and molecular characterization of some circulating strains of the peste-des-petits-ruminants virus in Saudi Arabia between 2014-2016

Background

The peste-des-petits-ruminants virus (PPRV) is a highly devastating virus of small ruminants in many parts of the world, including the Kingdome of Saudi Arabia. Therefore, our objectives were (1) to conduct a molecular prevalence study of PPRV in sheep and goat across the KSA and (2) to isolate and identify currently circulating PPRV lineages. Swabs and tissue specimens were collected from 97 herds suspected to be infected with PPRV across the Kingdome of Saudi Arabia (KSA). Testing for the presence of the virus was done by the real-time PCR. Confirmation of the identity of the reactions was done by the gel-based-PCR then by sequencing of the partial PPRV genome.

Results

Our results revealed that 24.1% of the tested specimens were PPRV-positive. Isolation of PPRV was successful from samples using the Vero cell line. Sequence analysis of some partial PPRV genes (N, F, M, L, P, and H) revealed that these strains were belonging to lineage IV of the PPRV.

Conclusions

This is the first study to conduct both the nationwide prevalence, isolation, and molecular characterizations of the PPRV in the KSA. Continuous surveillance and monitoring of the circulating strains of PPRV among sheep and goats will contribute substantially to the global eradication campaign of such a virus.

Paradigm shift in the diagnosis of peste des petits ruminants: scoping review

Peste des petits ruminants virus causes a highly contagious disease, which poses enormous economic losses in domestic animals and threatens the conservation of wild herbivores. Diagnosis remains a cornerstone to the Peste des petits ruminants Global Control and Eradication Strategy, an initiative of the World Organisation for Animal Health and the Food and Agriculture Organisation. The present review presents the peste des petits ruminants diagnostic landscape, including the practicality of commercially available diagnostic tools, prototype tests and opportunities for new technologies. The most common peste des petits ruminants diagnostic tools include; agar gel immunodiffusion, counter-immunoelectrophoresis, enzyme-linked immunosorbent assays, reverse transcription polymerase chain reaction either gel-based or real-time, reverse transcription loop-mediated isothermal amplification, reverse transcription recombinase polymerase amplification assays, immunochromatographic lateral flow devices, luciferase immunoprecipitation system and pseudotype-based assays. These tests vary in their technical demands, but all require a laboratory with exception of immunochromatographic lateral flow and possibly reverse transcription loop-mediated isothermal amplification and reverse transcription recombinase polymerase amplification assays. Thus, we are proposing an efficient integration of diagnostic tests for rapid and correct identification of peste des petits ruminants in endemic zones and to rapidly confirm outbreaks. Deployment of pen-side tests will improve diagnostic capacity in extremely remote settings and susceptible wildlife ecosystems, where transportation of clinical samples in the optimum cold chain is unreliable.

Early transcriptome profile of goat peripheral blood mononuclear cells (PBMCs) infected with peste des petits ruminant's vaccine virus (Sungri/96) revealed induction of antiviral response in an interferon independent manner

Sungri/96 vaccine strain is considered the most potent vaccine providing long-term immunity against peste des petits ruminants (PPR) in India. Previous studies in our laboratory highlighted induction of robust antiviral response in an interferon independent manner at 48 h and 120 h post infection (p.i.). However, immune response at the earliest time point 6 h p.i. (time taken to complete one PPRV life cycle), in PBMCs infected with Sungri/96 vaccine virus has not been investigated. This study was taken up to understand the global gene expression profiling of goat PBMCs after Sungri/96 PPRV vaccine strain infection at 6 h post infection (p.i.). A total of 1926 differentially expressed genes (DEGs) were identified with 616 - upregulated and 1310 - downregulated. TLR7/TLR3, IRF7/IRF1, ISG20, IFIT1/IFIT2, IFITM3, IL27 and TREX1 were identified as key immune sensors and antiviral candidate genes. Interestingly, type I interferons (IFNα/β) were not differentially expressed at this time point as well. TREX1, an exonuclease which inhibits type I interferons at the early stage of virus infection was found to be highly upregulated. IL27, an important antiviral host immune factor was significantly upregulated. ISG20, an antiviral interferon induced gene with exonuclease activity specific to ssRNA viruses was highly expressed. Functional profiling of DEGs showed significant enrichment of immune system processes with 233 genes indicating initiation of immune defense response in host cells. Protein interaction network showed important innate immune molecules in the immune network with high connectivity. The study highlights important immune and antiviral genes at the earliest time point.

The effects of PPR on the reproductive health of Black Bengal goats and the possible role played by oxidative stress

Outbreaks of Peste des petits ruminants (PPR) viral disease in Black Bengal goats were investigated from the middle Indo-Gangetic Plains of India. Clinical profile of PPR-affected flocks was recorded from four different outbreak sites of the region. The PPR outbreak was diagnosed serologically using commercially available sandwich ELISA kit. Relatively, low mortality rate (mean 26.75%) for PPR outbreak was recorded due to the endemic status of the disease. To understand the role of oxidative stress in PPR virus pathogenesis, various oxidant and antioxidant parameters in goats infected with PPR were estimated and compared with the uninfected/healthy goats of the same flock. The measured high level of pro-oxidant malondialdehyde (MDA) obtained from lipid peroxidation along with lower levels of anti-oxidants viz. superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in PPR-affected Black Bengal goats suggests oxidative stress as one of the mechanism of pathogenesis of PPR virus. In addition, the correlation of oxidative stress due to PPR and the resulting reproductive disorders in the female goats were evaluated. The abortion in pregnant does observed during PPR outbreak was proportional to debility and oxidative stress manifested during PPR infection. The reproductive performance of recovered female goats in the period of 18 months of monitoring was significantly compromised in terms of kidding and twinning frequency. The mortality rate in kids born from PPR-recovered goats was significantly higher compared to those from health goats in the first 9 months post-recovery. From the present study, it may be concluded that together with the PPR virus, infection in goats and the resulting oxidative stress play a vital role for abortion and reduced post-reproductive performance in Black Bengal female goat.

Peste des Petits Ruminants Virus Enters Caprine Endometrial Epithelial Cells via the Caveolae-Mediated Endocytosis Pathway

Peste des petits ruminants virus (PPRV) causes an acute and highly contagious disease of sheep and goats and has spread with alarming speed around the world. The pathology of Peste des petits ruminants is linked to retrogressive changes and necrotic lesions in lymphoid tissues and epithelial cells. However, the process of PPRV entry into host epithelial cells remains largely unknown. Here, we performed a comprehensive study of the entry mechanism of PPRV into caprine endometrial epithelial cells (EECs). We clearly demonstrated that PPRV internalization was inhibited by chloroquine and ammonium chloride, which elevate the pH of various organelles. However, PPRV entry was not affected by chlorpromazine and knockdown of the clathrin heavy chain in EECs. In addition, we found that the internalization of PPRV was dependent on dynamin and membrane cholesterol and was suppressed by silencing of caveolin-1. Macropinocytosis did not play a role, but phosphatidylinositol 3-kinase (PI3K) was required for PPRV internalization. Cell type and receptor-dependent differences indicated that PPRV entry into caprine fetal fibroblast cells (FFCs) occurred via a different route. Taken together, our findings demonstrate that PPRV enters EECs through a cholesterol-dependent caveolae-mediated uptake mechanism that is pH-dependent and requires dynamin and PI3K but is independent of clathrin. This potentially provides insight into the entry mechanisms of other morbilliviruses.

Peste des petits ruminants diagnosis and diagnostic tools at a glance: perspectives on global control and eradication

Peste des petits ruminants (PPR) is a highly contagious, economically important viral disease of small ruminants, targeted for global eradication by the year 2030. The recent geographic surge in PPR virus distribution, economic implications, the success of the rinderpest eradication campaign, and ongoing national/regional efforts convinced the FAO and OIE to initiate a global PPR control and eradication strategy. Since its discovery, a series of diagnostic tools have been developed for detecting PPR virus and virus-specific antibodies. Furthermore, it is understood that diagnostic and vaccine-monitoring tools are inevitable components of the four-stage strategy of global PPR eradication from assessment to the post-eradication phase. However, these tools may not be suitable for all stages of PPR control and eradication. For instance, diagnostics such as ELISA could be used for mass screening of clinical and serum samples, whereas immunochromatographic tests can be used at the field level as a pen-side test. Yet, assays with higher sensitivity, such as RT-PCR, RT-PCR ELISA, real-time RT-PCR and LAMP are important for early diagnosis of PPR and also, theoretically, during the late stages of eradication or when sampling non-natural hosts. Moreover, during the later stages of any control program, suspected/doubtful outbreaks will have to be reconfirmed using multiple laboratory tests. Hence, diagnostics can and should be efficiently applied at different stages of the PPR control and eradication campaign based on available resources and the number of samples to be tested. This article provides an overview of the various PPR diagnostic tools and suggests where and how they should be logically applied during the different phases of global PPR control and eradication.

Complexities in Isolation and Purification of Multiple Viruses from Mixed Viral Infections: Viral Interference, Persistence and Exclusion

Successful purification of multiple viruses from mixed infections remains a challenge. In this study, we investigated peste des petits ruminants virus (PPRV) and foot-and-mouth disease virus (FMDV) mixed infection in goats. Rather than in a single cell type, cytopathic effect (CPE) of the virus was observed in cocultured Vero/BHK-21 cells at 6^th blind passage (BP). PPRV, but not FMDV could be purified from the virus mixture by plaque assay. Viral RNA (mixture) transfection in BHK-21 cells produced FMDV but not PPRV virions, a strategy which we have successfully employed for the first time to eliminate the negative-stranded RNA virus from the virus mixture. FMDV phenotypes, such as replication competent but noncytolytic, cytolytic but defective in plaque formation and, cytolytic but defective in both plaque formation and standard FMDV genome were observed respectively, at passage level BP8, BP15 and BP19 and hence complicated virus isolation in the cell culture system. Mixed infection was not found to induce any significant antigenic and genetic diversity in both PPRV and FMDV. Further, we for the first time demonstrated the viral interference between PPRV and FMDV. Prior transfection of PPRV RNA, but not Newcastle disease virus (NDV) and rotavirus RNA resulted in reduced FMDV replication in BHK-21 cells suggesting that the PPRV RNA-induced interference was specifically directed against FMDV. On long-term coinfection of some acute pathogenic viruses (all possible combinations of PPRV, FMDV, NDV and buffalopox virus) in Vero cells, in most cases, one of the coinfecting viruses was excluded at passage level 5 suggesting that the long-term coinfection may modify viral persistence. To the best of our knowledge, this is the first documented evidence describing a natural mixed infection of FMDV and PPRV. The study not only provides simple and reliable methodologies for isolation and purification of two epidemiologically and economically important groups of viruses, but could also help in establishing better guidelines for trading animals that could transmit further infections and epidemics in disease free nations.

Silver nanoparticles impair Peste des petits ruminants virus replication

In the present study, we evaluated the antiviral efficacy of the silver nanoparticles (SNPs) against Peste des petits ruminants virus (PPRV), a prototype Morbillivirus. The leaf extract of the Argemone maxicana was used as a reducing agent for biological synthesis of the SNPs from silver nitrate. The SNPs were characterized using UV-vis absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM analysis revealed particle size of 5-30 nm and the XRD analysis revealed their characteristic silver structure. The treatment of Vero cells with the SNPs at a noncytotoxic concentration significantly inhibited PPRV replication in vitro. The time-course and virus step-specific assays showed that the SNPs impair PPRV replication at the level of virus entry. The TEM analysis showed that the SNPs interact with the virion surface as well with the virion core. However, this interaction has no direct virucidal effect, instead exerts a blocking effect on viral entry into the target cells. This is the first documented evidence indicating that the SNPs are capable of inhibiting a Morbillivirus replication in vitro.

Peste des petits ruminants virus infection of small ruminants: a comprehensive review

Peste des petits ruminants (PPR) is caused by a Morbillivirus that belongs to the family Paramyxoviridae. PPR is an acute, highly contagious and fatal disease primarily affecting goats and sheep, whereas cattle undergo sub-clinical infection. With morbidity and mortality rates that can be as high as 90%, PPR is classified as an OIE (Office International des Epizooties)-listed disease. Considering the importance of sheep and goats in the livelihood of the poor and marginal farmers in Africa and South Asia, PPR is an important concern for food security and poverty alleviation. PPR virus (PPRV) and rinderpest virus (RPV) are closely related Morbilliviruses. Rinderpest has been globally eradicated by mass vaccination. Though a live attenuated vaccine is available against PPR for immunoprophylaxis, due to its instability in subtropical climate (thermo-sensitivity), unavailability of required doses and insufficient coverage (herd immunity), the disease control program has not been a great success. Further, emerging evidence of poor cross neutralization between vaccine strain and PPRV strains currently circulating in the field has raised concerns about the protective efficacy of the existing PPR vaccines. This review summarizes the recent advancement in PPRV replication, its pathogenesis, immune response to vaccine and disease control. Attempts have also been made to highlight the current trends in understanding the host susceptibility and resistance to PPR.

Diagnosis and control of peste des petits ruminants: a comprehensive review

Peste des petits ruminants (PPR) is an acute, highly contagious, world organization for animal health (OIE) notifiable and economically important transboundary viral disease of sheep and goats associated with high morbidity and mortality and caused by PPR virus. PPR is considered as one of the main constraints in augmenting the productivity of small ruminants in developing countries and particularly severely affects poor farmer's economy. The disease is clinically manifested by pyrexia, oculo-nasal discharges, necrotizing and erosive stomatitis, gastroenteritis, diarrhoea and bronchopneumonia. The disease can be diagnosed from its clinical signs, pathological lesions, and specific detection of virus antigen/antibodies/genome in the clinical samples by various serological tests and molecular assays. PPR is the one of the priority animal diseases whose control is considered important for poverty alleviation in enzootic countries. Availability of effective and safe live attenuated cell culture PPR vaccines and diagnostics have boosted the recently launched centrally sponsored control programme in India and also in other countries. This review article primarily focus on the current scenario of PPR diagnosis and its control programme with advancement of research areas that have taken place in the recent years with future perspectives.