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Viruses Apr 2022African swine fever (ASF) is causing a pandemic affecting swine in a large geographical area of the Eastern Hemisphere, from Central Europe to East and Southeast Asia,... (Review)
Review
African swine fever (ASF) is causing a pandemic affecting swine in a large geographical area of the Eastern Hemisphere, from Central Europe to East and Southeast Asia, and recently in the Americas, the Dominican Republic and Haiti. The etiological agent, ASF virus (ASFV), infects both domestic and wild swine and produces a variety of clinical presentations depending on the virus strain and the genetics of the pigs infected. No commercial vaccines are currently available, although experimental recombinant live attenuated vaccine candidates have been shown to be efficacious in protecting animals against disease when challenged with homologous virulent strains. This review attempts to systematically provide an overview of all the live attenuated strains that have been shown to be experimental vaccine candidates. Moreover, it aims to analyze the development of these vaccine candidates, obtained by deleting specific genes or group of genes, and their efficacy in preventing virus infection and clinical disease after being challenged with virulent isolates. This report summarizes all the experimental vaccine strains that have shown promise against the contemporary pandemic strain of African swine fever.
Topics: African Swine Fever; African Swine Fever Virus; Animals; Swine; Vaccines, Attenuated; Vaccines, Synthetic; Viral Vaccines; Viruses, Unclassified
PubMed: 35632620
DOI: 10.3390/v14050878 -
Expert Review of Vaccines Dec 2017Before vaccination, varicella zoster virus (VZV), which is endemic worldwide, led to almost universal infection. This neurotropic virus persists lifelong by establishing... (Review)
Review
Before vaccination, varicella zoster virus (VZV), which is endemic worldwide, led to almost universal infection. This neurotropic virus persists lifelong by establishing latency in sensory ganglia, where its reactivation is controlled by VZV-specific T-cell immunity. Lifetime risk of VZV reactivation (zoster) is around 30%. Vaccine development was galvanised by the economic and societal burden of VZV, including debilitating zoster complications that largely affect older individuals. Areas covered: We describe the story of development, licensing and implementation of live attenuated vaccines against varicella and zoster. We consider the complex backdrop of VZV virology, pathogenesis and immune responses in the absence of suitable animal models and examine the changing epidemiology of VZV disease. We review the vaccines' efficacy, safety, effectiveness and coverage using evidence from trials, observational studies from large routine health datasets and clinical post-marketing surveillance studies and outline newer developments in subunit and inactivated vaccines. Expert commentary: Safe and effective, varicella and zoster vaccines have already made major inroads into reducing the burden of VZV disease globally. As these live vaccines have the potential to reactivate and cause clinical disease, developing alternatives that do not establish latency is an attractive prospect but will require better understanding of latency mechanisms.
Topics: Chickenpox; Chickenpox Vaccine; Clinical Trials as Topic; Drug Approval; Drug Discovery; Herpes Zoster; Herpes Zoster Vaccine; Humans; Product Surveillance, Postmarketing; Treatment Outcome; Vaccines, Attenuated; Vaccines, Subunit
PubMed: 29047317
DOI: 10.1080/14760584.2017.1394843 -
Science China. Life Sciences May 2020African swine fever (ASF) is a devastating infectious disease in swine that is severely threatening the global pig industry. An efficacious vaccine is urgently required....
African swine fever (ASF) is a devastating infectious disease in swine that is severely threatening the global pig industry. An efficacious vaccine is urgently required. Here, we used the Chinese ASFV HLJ/18 as a backbone and generated a series of gene-deleted viruses. The virulence, immunogenicity, safety, and protective efficacy evaluation in specific-pathogen-free pigs, commercial pigs, and pregnant sows indicated that one virus, namely HLJ/18-7GD, which has seven genes deleted, is fully attenuated in pigs, cannot convert to the virulent strain, and provides complete protection of pigs against lethal ASFV challenge. Our study shows that HLJ/-18-7GD is a safe and effective vaccine against ASFV, and as such is expected to play an important role in controlling the spread of ASFV.
Topics: African Swine Fever; African Swine Fever Virus; Animals; Gene Deletion; Genome, Viral; Humans; Recombinant Proteins; Sequence Analysis, DNA; Swine; Vaccines, Attenuated; Viral Proteins; Viral Vaccines; Virulence
PubMed: 32124180
DOI: 10.1007/s11427-020-1657-9 -
Genetically modified live attenuated vaccine: A potential strategy to combat visceral leishmaniasis.Parasite Immunology Sep 2020Visceral leishmaniasis (VL) is caused by a protozoan parasite Leishmania donovani mainly influencing the population of tropical and subtropical regions across the globe.... (Review)
Review
Visceral leishmaniasis (VL) is caused by a protozoan parasite Leishmania donovani mainly influencing the population of tropical and subtropical regions across the globe. The arsenal of drugs available is limited, and prolonged use of such drugs makes parasite to become resistant. Therefore, it is very imperative to develop a safe, cost-effective and inexpensive vaccine against VL. Although in recent years, many strategies have been pursued by researchers, so far only some of the vaccine candidates reached for clinical trial and more than half of them are still in pipeline. There is now a broad consent among Leishmania researchers that the perseverance of parasite is very essential for eliciting a protective immune response and may perhaps be attained by live attenuated parasite vaccination. For making a live attenuated parasite, it is very essential to ensure that the parasite is deficient of virulence and should further study genetically modified parasites to perceive the mechanism of pathogenesis. So it is believed that in the near future, a complete understanding of the Leishmania genome will explore clear strategies to discover a novel vaccine. This review describes the need for a genetically modified live attenuated vaccine against VL, and obstacles associated with its development.
Topics: Animals; Humans; Leishmania donovani; Leishmaniasis Vaccines; Leishmaniasis, Visceral; Vaccines, Attenuated
PubMed: 32418227
DOI: 10.1111/pim.12732 -
Bioanalysis Feb 2018Compared with biologics, vaccine potency assays represent a special challenge due to their unique compositions, multivalency, long life cycles and global distribution.... (Review)
Review
Compared with biologics, vaccine potency assays represent a special challenge due to their unique compositions, multivalency, long life cycles and global distribution. Historically, vaccines were released using in vivo potency assays requiring immunization of dozens of animals. Modern vaccines use a variety of newer analytical tools including biochemical, cell-based and immunochemical methods to measure potency. The choice of analytics largely depends on the mechanism of action and ability to ensure lot-to-lot consistency. Live vaccines often require cell-based assays to ensure infectivity, whereas recombinant vaccine potency can be reliably monitored with immunoassays. Several case studies are presented to demonstrate the relationship between mechanism of action and potency assay. A high-level decision tree is presented to assist with assay selection.
Topics: Animals; Biological Assay; Chlorocebus aethiops; Drug Evaluation, Preclinical; Enzyme-Linked Immunosorbent Assay; Hep G2 Cells; Humans; Immunogenicity, Vaccine; Mice; Vaccination; Vaccine Potency; Vaccines, Attenuated; Vaccines, Inactivated; Vaccines, Subunit; Vero Cells
PubMed: 29333863
DOI: 10.4155/bio-2017-0176 -
Frontiers in Immunology 2022Live vaccines use attenuated microbes to acquire immunity against pathogens in a safe way. As live attenuated vaccines (LAVs) still maintain infectivity, the vaccination... (Review)
Review
Live vaccines use attenuated microbes to acquire immunity against pathogens in a safe way. As live attenuated vaccines (LAVs) still maintain infectivity, the vaccination stimulates diverse immune responses by mimicking natural infection. Induction of pathogen-specific antibodies or cell-mediated cytotoxicity provides means of specific protection, but LAV can also elicit unintended off-target effects, termed non-specific effects. Such mechanisms as short-lived genetic interference and non-specific innate immune response or long-lasting trained immunity and heterologous immunity allow LAVs to develop resistance to subsequent microbial infections. Based on their safety and potential for interference, LAVs may be considered as an alternative for immediate mitigation and control of unexpected pandemic outbreaks before pathogen-specific therapeutic and prophylactic measures are deployed.
Topics: Immunity; Immunity, Heterologous; Vaccination; Vaccines, Attenuated
PubMed: 35651619
DOI: 10.3389/fimmu.2022.877845 -
Hong Kong Medical Journal = Xianggang... Dec 2019
Topics: Adolescent; Age Factors; Child; Child, Preschool; Hong Kong; Humans; Immunization Programs; Influenza Vaccines; Influenza, Human; Pandemics; Strategic Stockpile; Time Factors; Vaccines, Attenuated; Young Adult
PubMed: 31889031
DOI: No ID Found -
Current Opinion in Virology Oct 2020Infectious bursal disease (IBD), which is caused by infectious bursal disease virus (IBDV) infection, leads to severe immunosuppression in young chickens and results in... (Review)
Review
Infectious bursal disease (IBD), which is caused by infectious bursal disease virus (IBDV) infection, leads to severe immunosuppression in young chickens and results in significant economic losses in the poultry industry. To date, vaccination with live-attenuated vaccine (LAV) is a convenient method to provide effective protection against IBDV infection. Classical attenuated viruses are usually obtained by either passaging virus in cultured cells or natural isolation. However, these empiric attenuation methods, which are time-consuming and not guaranteed, are not reliable for emergent antigenic variant and very virulent IBDV strains. The reverse genetics (RG) system opens a new avenue for the development of IBDV LAV. In this review, we summarize the current knowledge on the biological characteristics of IBDV structure and genome organization, as well as the established RG systems. We also describe the details for the strategies used to develop IBDV LAV based on the RG systems.
Topics: Animals; Birnaviridae Infections; Chickens; Infectious bursal disease virus; Reverse Genetics; Vaccination; Vaccines, Attenuated; Viral Vaccines
PubMed: 32892072
DOI: 10.1016/j.coviro.2020.08.001 -
Human Vaccines & Immunotherapeutics Dec 2016Changing epidemiology of Hepatitis A virus (HAV) has led to an increased susceptibility of adolescents and adults to the infection. Vaccination can remarkably reduce the... (Review)
Review
Changing epidemiology of Hepatitis A virus (HAV) has led to an increased susceptibility of adolescents and adults to the infection. Vaccination can remarkably reduce the incidence and associated morbidity of HAV infection. This review is focused on the safety and efficacy of H2 strain derived live attenuated Hepatitis A vaccine. We found the vaccine to be highly immunogenic with minimal or negligible safety issues. Moreover, a single dose of live attenuated vaccine persists a long term immune response and can be a preferred option for developing countries. In 2014, Indian Academy of Paediatrics (IAP) also updated their recommendations for H2 vaccine as a single dose as against the previous 2 dose schedule. A focused approach to include the vaccine in national immunization program should be explored.
Topics: Child; Child, Preschool; Hepatitis A; Hepatitis A Vaccines; Humans; India; Vaccines, Attenuated
PubMed: 27532370
DOI: 10.1080/21645515.2016.1216286 -
Clinical and Translational Medicine Oct 2022
Topics: Influenza A Virus, H3N2 Subtype; Influenza Vaccines; Vaccines, Attenuated
PubMed: 36281705
DOI: 10.1002/ctm2.1081