Swati Sachan

Zika virus - emergence, evolution, pathology, diagnosis, and control: current global scenario and future perspectives - a comprehensive review.

ABSTRACT This review converses the Zika virus which has attained global concern due to its rapid pandemic potential and impact on humans. Though Zika virus was first isolated in 1947, till the recent large-scale outbreak which occurred in Micronesia, in 2007, the virus was placed into the innocuous pathogen category. The World Health Organization on 1 February 2016 declared it as a ‘Public Health Emergency of International Concern.’ Of the note, American as well as Pacific Island strains/isolates is relatively closer to Asian lineage strains. The African and American strains share more than 87.5% and 95% homologies with Asian strains/isolates, respectively. Asian strains form independent clusters, except those isolated from China, suggesting relatively more diversity than African strains. Prevention and control are mainly aimed at the vector population (mosquitoes) with Aedes aegypti being the main species. Surveys in Africa and Asia indicated seropositivity in various animal species. However, so far its natural reservoir is unknown. There is an urgent need to understand why Zika virus has shifted from being a virus that caused mild illness to unforeseen birth defects as well as autoimmune-neurological problems. Unfortunately, an effective vaccine is not available yet. Availability of cryo-electron microscopy based on 3.8 Å resolution revealing mature Zika virus structure and the probable virus attachment site to host cell would provide critical insights into the development of antiviral treatments and vaccines.

Advances in Developing Therapies to Combat Zika Virus: Current Knowledge and Future Perspectives

Zika virus (ZIKV) remained largely quiescent for nearly six decades after its first appearance in 1947. ZIKV reappeared after 2007, resulting in a declaration of an international “public health emergency” in 2016 by the World Health Organization (WHO). Until this time, ZIKV was considered to induce only mild illness, but it has now been established as the cause of severe clinical manifestations, including fetal anomalies, neurological problems, and autoimmune disorders. Infection during pregnancy can cause congenital brain abnormalities, including microcephaly and neurological degeneration, and in other cases, Guillain-Barré syndrome, making infections with ZIKV a substantial public health concern. Genomic and molecular investigations are underway to investigate ZIKV pathology and its recent enhanced pathogenicity, as well as to design safe and potent vaccines, drugs, and therapeutics. This review describes progress in the design and development of various anti-ZIKV therapeutics, including drugs targeting virus entry into cells and the helicase protein, nucleosides, inhibitors of NS3 protein, small molecules, methyltransferase inhibitors, interferons, repurposed drugs, drugs designed with the aid of computers, neutralizing antibodies, convalescent serum, antibodies that limit antibody-dependent enhancement, and herbal medicines. Additionally, covalent inhibitors of viral protein expression and anti-Toll-like receptor molecules are discussed. To counter ZIKV-associated disease, we need to make rapid progress in developing novel therapies that work effectually to inhibit ZIKV.

Synergy of lipopolysaccharide and resiquimod on type I interferon, pro-inflammatory cytokine, Th1 and Th2 response in chicken peripheral blood mononuclear cells

Toll-like receptors (TLRs) recognize conserved molecular structures of invading pathogens and initiate an immune response to curtail the infection prior to the development of more powerful and specific adaptive immunity. Understanding the interactions between different TLRs in terms of immune response genes is a pre-requisite for using various TLR agonists alone or in combination as adjuvants or as stand-alone agents against various diseases. Lipopolysaccharide (LPS) and resiquimod (R-848) are TLR agonists that are recognized by TLR4 and TLR7, respectively. In this study, the effect of LPS and/or R-848 on chicken peripheral blood mononuclear cells (PBMCs) was investigated. LPS and R-848 synergistically up-regulated the transcripts of interferon-β (IFN-β), IFN-γ, IL-4 and IL-1β as compared to the individual response (P<0.05). The results indicate that these agonists synergistically interact and enhance type-I IFN, pro-inflammatory cytokine as well as Th1 and Th2 responses in chicken PBMCs, suggesting their potential as an adjuvant candidate to be used in combination with various poultry vaccines.

Adjuvant potential of resiquimod with inactivated Newcastle disease vaccine and its mechanism of action in chicken

Resiquimod (R-848), an imidazoquinoline compound, is a potent synthetic Toll-like receptor (TLR) 7 agonist. Although the solitary adjuvant potential of R-848 is well established in mammals, such reports are not available in avian species hitherto. Hence, the adjuvant potential of R-848 was tested in SPF chicken in this study. Two week old chicks were divided into four groups (10 birds/group) viz., control (A), inactivated Newcastle disease virus (NDV) vaccine prepared from velogenic strain (B), commercial oil adjuvanted inactivated NDV vaccine prepared from lentogenic strain (C) and inactivated NDV vaccine prepared from velogenic strain with R-848 (D). Booster was given two weeks post primary vaccination. Humoral immune response was assessed by haemagglutination inhibition (HI) test and ELISA while the cellular immune response was quantified by lymphocyte transformation test (LTT) and flow cytometry post-vaccination. Entire experiment was repeated twice to check the reproducibility. Highest HI titre was observed in group D at post booster weeks 1 and 2 that corresponds to mean log2 HI titre of 6.4 ± 0.16 and 6.8 ± 0.13, respectively. The response was significantly higher than that of group B or C (P<0.01). LTT stimulation index (P ≤ 0.01) as well as CD4(+) and CD8(+) cells in flow cytometry (P<0.05) were significantly high and maximum in group D. Group D conferred complete protection against virulent NDV challenge, while it was only 80% in group B and C. To understand the effects of R-848, the kinetics of immune response genes in spleen were analyzed using quantitative real-time PCR after R-848 administration (50 μg/bird, i.m. route). Resiquimod significantly up-regulated the expression of IFN-α, IFN-β, IFN-γ, IL-1β, IL-4, iNOS and MHC-II genes (P<0.01). In conclusion, the study demonstrated the adjuvant potential of R-848 when co-administered with inactivated NDV vaccine in SPF chicken which is likely due to the up-regulation of immune response genes.

Ebola virus – epidemiology, diagnosis, and control: threat to humans, lessons learnt, and preparedness plans – an update on its 40 year's journey

ABSTRACT Ebola virus (EBOV) is an extremely contagious pathogen and causes lethal hemorrhagic fever disease in man and animals. The recently occurred Ebola virus disease (EVD) outbreaks in the West African countries have categorized it as an international health concern. For the virus maintenance and transmission, the non-human primates and reservoir hosts like fruit bats have played a vital role. For curbing the disease timely, we need effective therapeutics/prophylactics, however, in the absence of any approved vaccine, timely diagnosis and monitoring of EBOV remains of utmost importance. The technologically advanced vaccines like a viral-vectored vaccine, DNA vaccine and virus-like particles are underway for testing against EBOV. In the absence of any effective control measure, the adaptation of high standards of biosecurity measures, strict sanitary and hygienic practices, strengthening of surveillance and monitoring systems, imposing appropriate quarantine checks and vigilance on trade, transport, and movement of visitors from EVD endemic countries remains the answer of choice for tackling the EBOV spread. Herein, we converse with the current scenario of EBOV giving due emphasis on animal and veterinary perspectives along with advances in diagnosis and control strategies to be adopted, lessons learned from the recent outbreaks and the global preparedness plans. To retrieve the evolutionary information, we have analyzed a total of 56 genome sequences of various EBOV species submitted between 1976 and 2016 in public databases.

Prophylactic potential of resiquimod against very virulent infectious bursal disease virus (vvIBDV) challenge in the chicken

The study evaluated the prophylactic potential of resiquimod (R-848), a synthetic TLR7 agonist, against very virulent infectious bursal disease virus (vvIBDV) infection in chicken. Specific pathogen free White Leghorn chicks of three week age were treated with R-848 (50μg/bird, intramuscular) or PBS (n=26/group). Twenty four hour later, half of the birds from each group were challenged with 10(5) ELD50 of vvIBDV and observed for 10days. To understand the effect of R-848, immune response genes such as interferon (IFN)-β, IFN-γ, IL-1β, IL-4, iNOS and TLR7 were analyzed at 24 and 48h post-challenge in PBMCs ex vivo by real-time PCR (n=6/group). On day 4 post-challenge, representative birds (n=3/group) were sacrificed to study the bursal damage and IBDV antigen clearance. Immunosuppression was assessed by antibody response against live Newcastle disease virus (NDV) vaccine, which was administered on day 10 post-challenge. R-848 pre-treatment significantly upregulated the transcripts of each immune response gene studied (P<0.05). There was 50% mortality on vvIBDV challenge in control birds, while it was only 20% with R-848 group. R-848 pre-treatment reduced the bursal damage as indicated by lower bursal lesion score in histopathology, reduced IBDV antigen signal in immunohistochemistry and improved antigen clearance in agar gel immunodiffusion test. Further, it protected significantly against vvIBDV induced immunosuppression as indicated by HI antibody titre. It is concluded that pre-treatment of R-848 conferred partial protection from mortality and bursal damage while complete protection against immunosuppression in chicken when challenged with vvIBDV, which could be due to the upregulation of immune response genes.

Haemorrhagic enteritis of turkeys – current knowledge

ABSTRACT Haemorrhagic enteritis virus (HEV), an adenovirus associated with acute haemorrhagic gastro-intestinal disease of 6–11-week old turkeys predominantly hampers both humoral and cellular immunity. Affected birds are more prone to secondary complications (e.g. colibacillosis and clostridiosis) and failure to mount an effective vaccine-induced immune response. HEV belongs to the new genus Siadenovirus. Feco-oral transmission is the main route of entry of the virus and it mainly colonizes bursa, intestine and spleen. Both naturally occurring virulent and avirulent strains of HEVs are serologically indistinguishable. Recent findings revealed that ORF1, E3 and fib genes are the key factors affecting virulence. The adoption of suitable diagnostic tools, proper vaccination and biosecurity measures have restrained the occurrence of disease epidemics. For diagnostic purposes, the best source of HEV is either intestinal contents or samples from spleen. For rapid detection highly sensitive and specific tests such as quantitative real-time PCR based on Taq man probe has been designed. Avirulent strains of HEV or MSDV can be effectively used as live vaccines. Novel vaccines include recombinant hexon protein-based subunit vaccines or recombinant virus-vectored vaccines using fowl poxvirus (FPV) expressing the native hexon of HEV. Notably, subunit vaccines and recombinant virus vectored vaccines altogether offer high protection against challenge or field viruses. Herein, we converse a comprehensive analysis of the HEV genetics, disease pathobiology, advancements in diagnosis and vaccination along with appropriate prevention and control strategies.

Administration of TLR7 agonist, resiquimod, in different types of chicken induces a mixed Th1 and Th2 response in the peripheral blood mononuclear cells

This study evaluated the variation in immune response in peripheral blood mononuclear cells (PBMCs) of broiler, White Leghorn (WL) and Kadaknath breeds of chicken following administration of TLR7 agonist, resiquimod (R-848). Expression of different immune related genes viz., interferon-β (IFN-β), IFN-γ, IL-1β, IL-4, TLR7 and iNOS was assessed by quantitative real time PCR over a period of 24 h. The results indicated that there was a significant up-regulation in the relative expression of immune response genes post R-848 administration (P < 0.01). In conclusion, the transcriptional expression of IFN-β, IFN-γ, IL-1β, IL-4, iNOS and TLR7 genes in the PBMCs was significantly up-regulated over 24 h in broiler, WL and Kadaknath breeds of birds after the administration of R-848. Overall, R-848 induced a mixed Th1 and Th2 response in PBMCs of chicken origin ex vivo.

The use of probiotics as eco-friendly alternatives for antibiotics in poultry nutrition

Antibiotics as growth promoters in poultry have been used for long time for improving feed efficiency and performance. Due to their various side-effects such as antibiotic resistance, destruction of beneficial bacteria in the gut, and dysbiosis, it is required to think about some alternatives. Probiotics are one of the options in this regard for improving poultry production. Probiotics are defined as “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host.” They are available in various forms for use as feed additives. Probiotics as feed additives aid in proper digestion of feed hence make the nutrients available for faster growth. Immunity can also be improved by addition of probiotics to poultry diets. Moreover, probiotics aid in improving meat and egg quality traits. Various infectious diseases of poultry can be countered by use of probiotics in their feed. A proper selection of probiotic strains is required for gaining optimal effects. This review focuses on the mechanisms of action of probiotics and their importance in poultry feed supplementation for enhancing production and safeguarding health of poultry.

Studies on Pest Complex and Seasonal Incidence of Shoot Fly, Atherigona Soccata (Rondani) on Maize in Western U.P.

An investigation to study the pest complex and seasonal incidence of shoot fly, Atherigona soccata (Rondani) in maize was carried out for two consecutive seasons i.e. 2013 and 2014. During the experimentation, eleven insect species were found attacking on different growth stage of maize crop, out of these stem borer, Chilo partellus (Swinhoe) and shoot fly, A. soccata (Rondani) were recorded as major pests, two insect Rhopalosiphum maidis and Pyrilla perpusilla was recorded as stray pests while other seven insects were appeared as minor insects to this region. The peak number of egg laid by shoot fly 2.27 and 2.37 egg/plant were recorded at end week of March (13th Standard Week) during the years, 2013 and 2014, respectively. The peak dead heart caused by shoot fly 26.18 and 26.40 per cent was recorded at first week of April (14th Standard Week) during the both years of experimentation i.e. 2013 and 2014, respectively. In case of shoot fly incidence among the weather factors, only morning and evening relative humidity showed positive correlation while other had negative correlation.