Immunization with baculovirus displayed H6 hemagglutinin vaccine protects mice against lethal H6 influenza virus challenge

Evolution and Reassortment of H6 Subtype Avian Influenza Viruses

The H6 subtype of avian influenza virus (H6 AIV) is the most detected AIV subtype in poultry and wild birds. It causes economic losses to the poultry industry, and the most important, H6 AIV may have the ability to infect mammals, which is a great threat to public health security. In addition, the H6 subtype can serve as a precursor to providing internal genes for other highly pathogenic AIVs, posing a potential threat. H6 AIV currently face to the high positive detection rate and harmless nature of H6 AIV and because not highly effective H6 subtype vaccine available on the market. In this study, we focused on the prevalence of H6 AIV in poultry and wild birds, phylogenetic analysis, genetic variation characteristics, selection analysis, and prevention and control to provide relevant references for the scientific prevention and control of H6 AIV in future.

Baculovirus Display of Peptides and Proteins for Medical Applications

Baculoviridae is a large family of arthropod-infective viruses. Recombinant baculoviruses have many applications, the best known is as a system for large scale protein production in combination with insect cell cultures. More recently recombinant baculoviruses have been utilized for the display of proteins of interest with applications in medicine. In the present review we analyze the different strategies for the display of proteins and peptides on the surface of recombinant baculoviruses and provide some examples of the different proteins displayed. We analyze briefly the commercially available systems for recombinant baculovirus production and display and discuss the future of this emerging and powerful technology.

Vaccines against Major Poultry Viral Diseases: Strategies to Improve the Breadth and Protective Efficacy

The poultry industry is the largest source of meat and eggs for human consumption worldwide. However, viral outbreaks in farmed stock are a common occurrence and a major source of concern for the industry. Mortality and morbidity resulting from an outbreak can cause significant economic losses with subsequent detrimental impacts on the global food supply chain. Mass vaccination is one of the main strategies for controlling and preventing viral infection in poultry. The development of broadly protective vaccines against avian viral diseases will alleviate selection pressure on field virus strains and simplify vaccination regimens for commercial farms with overall savings in husbandry costs. With the increasing number of emerging and re-emerging viral infectious diseases in the poultry industry, there is an urgent need to understand the strategies for broadening the protective efficacy of the vaccines against distinct viral strains. The current review provides an overview of viral vaccines and vaccination regimens available for common avian viral infections, and strategies for developing safer and more efficacious viral vaccines for poultry.

Induction of mucosal immunity against pathogens by using recombinant baculoviral vectors: Mechanisms, advantages, and limitations

Over 90% of pathogens of medical importance invade the organism through mucosal surfaces, which makes it urgent to develop safe and effective mucosal vaccines and mucosal immunization protocols. Besides, parenteral immunization does not provide adequate protective immunity in mucosal surfaces. Effective mucosal vaccination could protect local and systemic compartments and favor herd immunity. Although various mucosal adjuvants and Ag-delivery systems have been developed, none has filled the gap to control diseases caused by complex mucosal pathogens. Among the strategies to counteract them, recombinant virions from the baculovirus Autographa californica multiple nucleopolyhedrovirus (rAcMNPV) are useful vectors, given their safety and efficacy to produce mucosal and systemic immunity in animal infection models. Here, we review the immunogenic properties of rAcMNPV virions from the perspectives of mucosal immunology and vaccinology. Some features, which are analyzed and extrapolated from studies with different particulate antigens, include size, shape, surface molecule organization, and danger signals, all needed to break the tolerogenic responses of the mucosal immune tissues. Also, we present a condensed discussion on the immunity provided by rAcMNPV virions against influenza virus and human papillomavirus in animal models. Through the text, we highlight the advantages and limitations of this experimental immunization platform.

A secretary bi-cistronic baculovirus expression system with improved production of the HA1 protein of H6 influenza virus in insect cells and Spodoptera litura larvae

A bi-cistronic baculovirus expression vector was constructed to facilitate the expression, detection, and isolation of the hemagglutinin (HA) fragment HA1 of H6N1 avian influenza virus (AIV) in an insect and a culture of its cells. In this construct, the GP67sp signal peptide promoted the secretion of the recombinant protein into the culture medium, and improved protein expression and purification. Enhanced green fluorescent protein, co-expressed through an internal ribosome entry site, served as a visible reporter for protein expression detection. The hemolymph of Spodoptera litura larvae infected with the bi-cistronic baculovirus was collected for the purification of the recombinant HA1, which was found to be glycosylated, and monomeric and trimeric forms of the recombinant HA1 were identified. Proteins expressed in both the cell culture and larvae served as effective subunit vaccines for the production of antiserum against HA. The antiserum recognized the H6 subtype of AIV but not the H5 subtype.

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HA1 of H6N1 influenza virus was expressed in insect and cell culture.

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The expressed HA1 was glycosylated, and estimated as monomeric and trimeric forms.

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The expressed HA1 served as an effective subunit vaccine for producing antisera.

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The antisera specifically recognized influenza H6 subtype but not the H5 subtype.

Baculovirus Surface Display of Immunogenic Proteins for Vaccine Development

Vaccination is an efficient way to prevent the occurrence of many infectious diseases in humans. To date, several viral vectors have been utilized for the generation of vaccines. Among them, baculovirus-categorized as a nonhuman viral vector-has been used in wider applications. Its versatile features, like large cloning capacity, nonreplicative nature in mammalian cells, and broad tissue tropism, hold it at an excellent position among vaccine vectors. In addition to ease and safety during swift production, recent key improvements to existing baculovirus vectors (such as inclusion of hybrid promoters, immunostimulatory elements, etc.) have led to significant improvements in immunogenicity and efficacy of surface-displayed antigens. Furthermore, some promising preclinical results have been reported that mirror the scope and practicality of baculovirus as a vaccine vector for human applications in the near future. Herein, this review provides an overview of the induced immune responses by baculovirus surface-displayed vaccines against influenza and other infectious diseases in animal models, and highlights the strategies applied to enhance the protective immune responses against the displayed antigens.

Viral vector-based influenza vaccines

Antigenic drift of seasonal influenza viruses and the occasional introduction of influenza viruses of novel subtypes into the human population complicate the timely production of effective vaccines that antigenically match the virus strains that cause epidemic or pandemic outbreaks. The development of game-changing vaccines that induce broadly protective immunity against a wide variety of influenza viruses is an unmet need, in which recombinant viral vectors may provide. Use of viral vectors allows the delivery of any influenza virus antigen, or derivative thereof, to the immune system, resulting in the optimal induction of virus-specific B- and T-cell responses against this antigen of choice. This systematic review discusses results obtained with vectored influenza virus vaccines and advantages and disadvantages of the currently available viral vectors.