Starch is the main storage biopolymer in cereal plants. Several enzymes and carrier proteins are involved in the starch biosynthesis process. ADP-glucose pyrophosphorylase (AGPase) has been characterized as a key factor in this process, which catalyzes the conversion of glucose 1-phosphate into ADP-glucose in the cytosol of the endospermic cell. The freshly synthesized ADP-glucose must be transported into amyloplasts by the activity of ADP-glucose transporter. In the current research, we have characterized HvBT1 biochemically in E. coli system. HvBT1 shows high affinity to ADP-glucose as a transport substrate in counter-exchange with ADP with affinities of 614 and 334 µM, respectively. The cellular and subcellular localization of HvBT1 indicated its target the amyloplasts envelopes. The comparison between two barley cultivars; Harrington and Golden Promise shed some light on the impact of HvBT1 on starch accumulation. Higher expression of AGPase and HvBT1 (10 fold) provide an ideal combination for improving starch yield, where starch content was higher by 2.5% in Harrington. Unlike Harrington, the expression of soluble starch synthase encoded genes was higher in Golden Promise which accumulates less starch. This result provided evidence of the importance of HvBT1 in starch synthesis process along with AGPase. Down-regulation of HvBT1 also provided a cement evidence of its effect on the starch accumulation process, where the knock down lines showed 17% lower starch and altered starch composition. Also, as a result of decreasing starch, protein content increased in the transgenic grains by 4-5 % of its content in the wild type, while β-glucan was 37% lower than the wild type control. Down-regulation of HvBT1 led to decrease the grain yield by ~ 30% as a result of increase the grain size. Also, it seems to have pleotropic effects on other starch synthesis genes, where AGPLs was down-regulated while the plastidial SSU genes, AGPS1b and S2 were up-regulated. Soluble starch synthases SS2a and SS3a were down-regulated, while SS2b was up-regulated in the transgenic plants. The accumulated evidences indicated that HvBT1 is a key factor in starch biosynthesis process. / February 2015

Coccidiosis is a costly parasitic disease to the poultry industry with multiple prevention methods being explored to control its impact. One approach under development is the use of -glucans, which are carbohydrates from cell walls of various plant species. The first study evaluated the feeding effects of algae- derived -glucans on performance and responses of broilers during a coccidiosis challenge. Cobb 500 broilers (n=1280) were fed a control diet, control supplemented with 150 g/MT Algamune (BG), 100 g/MT Algamune ZPC (BGZn), or 0.01% Salinomycin (Sal). On d 15, challenged birds received mixed Eimeria inoculum. Measurements were taken on d 7, 14, 21, and 28, and lesion scores assessed on d 21. The challenge resulted in reduced BW, and higher feed conversion ratio (FCR) was observed in the challenged birds with Sal and BGZn. Escherichia coli (E. coli) is normally commensal to the gastrointestinal tract, but certain serotypes cause disease in domestic poultry. A subsequent study was conducted to evaluate the feeding effects of algae-derived glucan (1,3 -glucan) on performance of broiler chickens during an E. coli challenge. Cobb 500 broilers (n=900) were fed a control diet, control + 25 mg/kg of -glucan, or control + 100 mg/kg of -glucan. On d 0, litter was sprayed with E. coli inoculum. Measurements were taken on d 7, 14, 21, and 28. -glucan supplementation increased BW gain andlowered FCR. The results from these studies offer some insight to the effects of -glucans on poultry and their potential to offset negative effects caused by infectious challenges. / Master of Science

Limited information exists regarding the effects of light pearling on the properties of physical grain characteristics, composition, and technological and sensory properties of selected varieties of Western Canadian barley especially hulless barley genotypes with modified starch characteristics. Nine barley genotypes with different hull (hulled and hulless) and starch characteristics (normal, waxy, and high amylose (HA)) were pearled to three differing levels. Scanning electron micrographs showed that the pericarp, testa, aleurone, and subaleurone layers were completely removed in heavily pearled barley whereas only a few outer layers were removed in minimally pearled barley. Waxy starch genotype Fibar and HA starch genotypes, SH99250 & SB94893 contained high levels of soluble β-glucan (9-11%). Waxy starch genotypes exhibited higher β-glucan solubility when cooked compared to normal and HA starch genotypes. However, HA starch genotypes had lower in vitro starch digestibility which may provide a lower glycemic response in humans.

Limited information exists regarding the effects of light pearling on the properties of physical grain characteristics, composition, and technological and sensory properties of selected varieties of Western Canadian barley especially hulless barley genotypes with modified starch characteristics. Nine barley genotypes with different hull (hulled and hulless) and starch characteristics (normal, waxy, and high amylose (HA)) were pearled to three differing levels. Scanning electron micrographs showed that the pericarp, testa, aleurone, and subaleurone layers were completely removed in heavily pearled barley whereas only a few outer layers were removed in minimally pearled barley. Waxy starch genotype Fibar and HA starch genotypes, SH99250 & SB94893 contained high levels of soluble β-glucan (9-11%). Waxy starch genotypes exhibited higher β-glucan solubility when cooked compared to normal and HA starch genotypes. However, HA starch genotypes had lower in vitro starch digestibility which may provide a lower glycemic response in humans.

Os b-glucanos são formados por polissacarídeos estruturais da parede celular de leveduras (Saccharomyces cerevisiae), alguns cereais em grãos e fungos. Os b-glucanos apresentam a molécula de glicose ligada ao carbono nas posições b-1,3 e pode apresentar cadeias laterais com o resíduo de glicose ligado nas posições b-1,6. O b-glucano tem sua ação benéfica como antiinflamatório, antitumoral, hipocolesterolêmico e hipoglicêmico. A inocuidade do b-glucano solubilizado nesse trabalho foi demonstrada in vitro, em cultivo celular de fibroblastos de embriões de galinhas SPF, e confirmado in vivo após a injeção no músculo peitoral de frangos. O b-glucano é um modulador biológico devido sua capacidade de em aumentar a resposta imune inata, aumentando os mecanismos inespecíficos de defesa dos animais. O b-glucano solúvel na dose de 240 mg/ave, associado ao diluente da vacina de Marek, apresentou efeito imunomodulador na resposta imune humoral. Os níveis de IgG no plasma foram detectados pela técnica de ELISA, e a resposta imune celular foi avaliada pela detecção de IFNg-, IL-2 e IL-6 em frangos vacinados com vacina recombinante e viva contra doença de Gumboro. O b-glucano solúvel nesse experimento demonstrou ser um potente imunoadjuvante após aumentar a resposta imune humoral e celular para os antígenos da doença infecciosa da Bursa, quando associado em vacinas recombinantes e vivas. / The b-glucans are structural polysaccharides from yeast cell wall (Saccharomyces cerevisiae), some cereal grains and fungi. The b-glucans have a glucose molecule carbon linked in sites b-1,3 and they have side chains of glucose residue in sites b-1,6. The b-glucans have a helpful effect as anti-inflammatory, antitumoral, hypoglycemic and hypocholesterolemic activity .The safety of b-glucan water-soluble obtained in this work was demonstrated in vitro, using specific-pathogen-free (SPF) cell culture chicken embryo fibroblast and it was confirmed in vivo after injection in chicken pectoral muscle. The b-glucan is a biological modulator due to its ability to increase the innate immune response. The soluble b-glucan in 240 mg/bird dose, associated to Marek\'s disease vaccine diluents showed immunomodulatory effect in humoral immune response. The IgG plasma levels were detected by ELISA method, and the cellular immune response was evaluated by detection IFN-g, IL-2 and IL-6 in vaccinated chickens with recombinant and live vaccines against Gumboro\'s disease using Real-Time PCR technique. The soluble b-glucan used in this trial demonstrated a powerful immune-adjuvant effect enhancing the cellular and humoral immune response against Bursal disease, when associated to recombinant vaccine and live vaccines.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2016-12-14T16:06:41Z No. of bitstreams: 2 Dissertação - Grazzielle Guimarães de Matos - 2016.pdf: 6175984 bytes, checksum: 49ee98e2341033b338755369c46b165a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Jaqueline Silva (jtas29@gmail.com) on 2016-12-15T17:30:05Z (GMT) No. of bitstreams: 2 Dissertação - Grazzielle Guimarães de Matos - 2016.pdf: 6175984 bytes, checksum: 49ee98e2341033b338755369c46b165a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-12-15T17:30:05Z (GMT). No. of bitstreams: 2 Dissertação - Grazzielle Guimarães de Matos - 2016.pdf: 6175984 bytes, checksum: 49ee98e2341033b338755369c46b165a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-03-04 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In Brazil, L. (V.) braziliensis is specie responsible for many cases of American Tegumentary Leishmaniasis (ETL). To effective vaccine development, formulations contained immunogenic antigens associated with adjuvants that induce a T helpe 1 (Th1) immune response are been investigated, among of antigen have the “Thiol Specific Antioxidant” (rTSA), “Stress Inducible protein 1” (rSTI) and “Leishmania elongation initiation fator” (rLeIF) of L. major, which have been immunogenic and promising. The genes that corresponding to these antigens in L. (V.) braziliensis were sequenced and recombinants proteins were obtained and used in this study. Works that used BCG and β-glucan showed that these could provide protection against not related pathogens. The present study had as aim to evaluate the immunogenicity and the effectiveness of the vaccine using the rTSA, rSTI and rLeIF proteins (Triple), associated or not with β-glucan, with or without BCG stimulus. BALB/c mice were divided in 2 groups, one of the groups was stimulated with BCG and the other not. Posteriorly, the animals were divided in subgroups and vaccinated with triple, associated or not with β-glucan. Mice’s serum were collected to search of cytokines and antibodies by immunoenzymatic technique. Lymph node and spleen’s cells were cultivated and cytokines searched in supernatants. BCG stimulation induced a greater IFN-γ production. The vaccinated mice with triple produced IgG total, IgG1 and IgG2a specifics to L. (V.) braziliensis. BCG stimulation induced a high IgG total and IgG2a production in animals that received the triple without β-glucan. To evaluate the protection provided by vaccine, the immunized animals were infected with L. (V.) braziliensis and paw them measured along of 8 weeks. The subgroup don’t stimulated with BCG and vaccinated with triple, associated with β-glucan, has developed bigger lesions that the others subgroups. The subgroups that received only BCG stimulation or BCG stimulation and vaccine with triple plus β-glucan presented bigger lesions that animal don’t stimulated or vaccinated. After infection by L. (V.) braziliensis, (i) the animals stimulated with BCG and vaccinated with triple presents more IgG specific to L. (V.) braziliensis; (ii) the immunizations with triple maintained IFN-γ levels elevated; (iii) all animals presented lower IL-17 levels in serum; (iv) the subgroups produced similar IFN-γ levels, but with a high IL-17 production in subgroup vaccinated with triple plus β-glucan, don’t BCG stimulated, in spleen; (v) the animals that received only BCG produced more IFN-γ and IL-17 in lymph node. In conclusion: the immunizations with triple were immunogenic; the immunization scheme containing triple plus β- glucan, without BCG stimulation, provided partial protection against L. (V.) braziliensis infection; BCG stimulations induced biggest lesions in subgroup that received only saline or triple plus β-glucan; the vaccination scheme containing triple maintained high IFN-γ production after L. (V.) braziliensis infection; in infection site, the BCG stimulation induced a Th1/Th17 heterologous response. / No Brasil, L. (V.) braziliensis é a espécie responsável pela maioria dos casos de Leishmaniose Tegumentar Americana (LTA). Para o desenvolvimento de uma vacina eficaz, formulações contendo antígenos imunogênicos, associados com adjuvantes, indutores de uma resposta imune do perfil T auxiliar 1 (Th1), estão sendo investigados, entre eles têm-se o “Thiol Specific Antioxidant” (rTSA), a “Stress Inducible protein 1” (rSTI) e o “Leishmania elongation initiation fator” (rLeIF) de L. major, que se mostraram imunogênicos e promissores. Os genes destas proteínas, de L. (V.) braziliensis, foram sequenciados e as proteínas recombinantes obtidas e utilizadas neste estudo. Trabalhos utilizando BCG e β-glucana mostraram a capacidade destes em fornecer proteção inespecífica. O presente estudo teve como objetivo avaliar a imunogenicidade e a eficácia da vacina com as proteínas rTSA, rSTI e Leif (Tríplice) de L. (V.) braziliensis associadas com o adjuvante β-glucana, com ou sem estímulo prévio com BCG. Camundongos BALB/c foram divididos em 2 grupos, um deles inoculado com BCG e o outro não. Posteriormente, os animais foram divididos em subgrupos e vacinados com tríplice, associadas ou não com β-glucana. Foram coletados os soros dos animais para dosagem de citocinas e anticorpos pela técnica imunoenzimática. Células do baço e linfonodo drenante foram cultivadas para dosagem de citocinas no sobrenadante. O estimulo com BCG induziu uma maior produção de IFN-γ. Os camundongos vacinados com a tríplice produziram anticorpos IgG total, IgG1 e IgG2a específicos para L. (V.) braziliensis. O estimulo com BCG induziu uma maior produção de anticorpos IgG total e IgG2a, nos animais vacinados com a tríplice sem β-glucana. Para avaliar a proteção fornecida pela vacina, os animais imunizados foram infectados com L. (V.) braziliensis e as patas mensuradas durante 8 semanas. O subgrupo, não estimulado com BCG e vacinado com a tríplice, associada com β-glucana, desenvolveu lesões menores que os demais subgrupos (p<0,05). Os subgrupos que receberam apenas BCG ou foram vacinados com a tríplice mais β-glucana apresentaram lesões maiores que os animais não estimulados e imunizados (p<0,05). Após a infecção por L. (V.) braziliensis, (i) os animais estimulados e vacinados com a tríplice apresentaram níveis elevados de IgG específicos para L. (V.) braziliensis; (ii) as imunizações com a tríplice mantiveram os níveis de IFN-γ aumentados (p<0,05); (iii) todos os animais apresentaram menores concentrações de IL-17, no soro; (iv) houve detecção similar de IFN-γ entre os subgrupos, mas com uma maior produção de IL-17 no subgrupo vacinado com a tríplice mais β-glucana, não estimulados com BCG, no baço (p<0,05); (v) os animais que receberam apenas BCG produziram mais IFN-γ e IL-17, no linfonodo drenante. Conclui-se que: as imunizações com tríplice foram imunogênicas; o esquema de imunização com a tríplice mais β-glucana, sem estimulo com BCG, forneceu proteção parcial contra a infecção por L. (V.) braziliensis; o estimulo com BCG induziu lesões maiores nos subgrupos que receberam salina ou a tríplice mais β- glucana; o esquema de vacinação com a tríplice manteve a produção de IFN-γ elevada após a infecção por L. (V.) braziliensis; no sitio de infecção, o estimulo com a BCG levou a uma resposta heteróloga Th1/Th17.

Os b-glucanos são formados por polissacarídeos estruturais da parede celular de leveduras (Saccharomyces cerevisiae), alguns cereais em grãos e fungos. Os b-glucanos apresentam a molécula de glicose ligada ao carbono nas posições b-1,3 e pode apresentar cadeias laterais com o resíduo de glicose ligado nas posições b-1,6. O b-glucano tem sua ação benéfica como antiinflamatório, antitumoral, hipocolesterolêmico e hipoglicêmico. A inocuidade do b-glucano solubilizado nesse trabalho foi demonstrada in vitro, em cultivo celular de fibroblastos de embriões de galinhas SPF, e confirmado in vivo após a injeção no músculo peitoral de frangos. O b-glucano é um modulador biológico devido sua capacidade de em aumentar a resposta imune inata, aumentando os mecanismos inespecíficos de defesa dos animais. O b-glucano solúvel na dose de 240 mg/ave, associado ao diluente da vacina de Marek, apresentou efeito imunomodulador na resposta imune humoral. Os níveis de IgG no plasma foram detectados pela técnica de ELISA, e a resposta imune celular foi avaliada pela detecção de IFNg-, IL-2 e IL-6 em frangos vacinados com vacina recombinante e viva contra doença de Gumboro. O b-glucano solúvel nesse experimento demonstrou ser um potente imunoadjuvante após aumentar a resposta imune humoral e celular para os antígenos da doença infecciosa da Bursa, quando associado em vacinas recombinantes e vivas. / The b-glucans are structural polysaccharides from yeast cell wall (Saccharomyces cerevisiae), some cereal grains and fungi. The b-glucans have a glucose molecule carbon linked in sites b-1,3 and they have side chains of glucose residue in sites b-1,6. The b-glucans have a helpful effect as anti-inflammatory, antitumoral, hypoglycemic and hypocholesterolemic activity .The safety of b-glucan water-soluble obtained in this work was demonstrated in vitro, using specific-pathogen-free (SPF) cell culture chicken embryo fibroblast and it was confirmed in vivo after injection in chicken pectoral muscle. The b-glucan is a biological modulator due to its ability to increase the innate immune response. The soluble b-glucan in 240 mg/bird dose, associated to Marek\'s disease vaccine diluents showed immunomodulatory effect in humoral immune response. The IgG plasma levels were detected by ELISA method, and the cellular immune response was evaluated by detection IFN-g, IL-2 and IL-6 in vaccinated chickens with recombinant and live vaccines against Gumboro\'s disease using Real-Time PCR technique. The soluble b-glucan used in this trial demonstrated a powerful immune-adjuvant effect enhancing the cellular and humoral immune response against Bursal disease, when associated to recombinant vaccine and live vaccines.

To understand and modify the secondary cell walls of plants the project group Enzyme Discovery in Hybrid Aspen for Fiber Engineering (EDEN) was founded composed of nine laboratories with funding from the European Commission. The main target of EDEN´s research is to genetically engineer fiber structure in order to produce transgenic trees with modified properties for the pulp and paper industries. In this target framework, the Populus tremula x tremuloides xyloglucan endotransglycosylase (PttXET16A) was selected for in-depth study of its transglycosylase activity catalyzing cleavage and reconnection of xyloglucan molecules, which is proposed to be involved in secondary cell wall morphogenesis. The creation of a family 16 carbohydrate active enzyme &#61538;-glucanase/XET hybrids were attempted in order to design a chimeric enzyme with one or more of the following altered properties: specificity, activity, and or stability. The two enzymes, Bacillus licheniformis 1,3-1,4-&#61538;-glucanase and Populus tremula x tremuloides xyloglucan endotransglycosylase, are members of the same enzymatic family and have highly homologous 3-dimensional structures. However, the enzymes exhibit different activities, one a hydrolase the other a transferase; different specificities, one accepts only linear glcosydic substrates while the other branched substrates; and different stabilities. Hybrid enzyme construction represented an investigational challenge in order to understand what physical characteristics of both enzymes attribute to the specific pattern of activity and specificity observed.Removal of the 1,3-1,4-&#61538;-glucanase major loop resulted in a folded protein which still maintained some &#946;-glucan hydrolase activity. However, no xyloglucan endotransglycosylase-like activity or specificity was observed. Next, point mutations of the &#946;-sheets forming the enzymatic binding site cleft were mutated to resemble PttXET16A residues. The final chimeric protein neither exhibited XET nor &#946;-glucanase activities. Structural analysis by X-ray crystallography revealed a major unexpected structural rearrangement providing a clear insight for further enzyme engineering. / Amb la finalitat d'entendre i modificar la paret cel·lular secundària de les plantes, es va fundar el grup Enzyme Discovery in Hibrid Aspen for Fibern Engineering (EDEN) composat per nou laboratoris amb la finançament de la Comissió Europea. El principal objectiu de la recerca del grup EDEN és enginyar genèticament l'estructura de fibres per tal de produir arbres transgènics amb propietats modificades per les indústries de la polpa i el paper.En el marc d'aquest projecte, es va seleccionar el Populus tremula x tremuloides xiloglucà endotransglicosilasa (PttXET16A) per estudiar en profunditat la seva activitat transglicosilasa catalitzant el trencament i la reconnexió de molècules de xiloglucà, el qual sembla estar involucrat en la morfogènesi de la paret cel·lular secundària. D'aquesta manera, s'intentà crear una família 16 d'híbrids de l'enzim actiu amb carbohidrats &#61538;-glucanasa/XET per tal de dissenyar un enzim quimèric amb una o més de les propietats següents alterades: especificitat, activitat i/o estabilitat.Els dos enzims, Bacillus licheniformis 1,3-1,4-&#61538;-glucanasa i Populus tremula x tremuloides xiloglucà endotransglicosilasa, són membres de la mateixa família enzimàtica i tenen una gran homologia en les seves estructures en 3-dimensions. Tot i així, aquests enzims presenten diferents activitats, un presenta activitat hidrolasa i l'altre, transferasa; diferents especificitats, un accepta només substrats glicosílics lineals mentre l'altre, substrats ramificats; i diferents estabilitats. La construcció d'un enzim híbrid representa un repte en la investigació amb la finalitat d'entendre quines característiques físiques dels dos enzims s'atribueixen al model específic de l'activitat i especificitat observada.L'extracció del llaç més gran de l'1,3-1,4-&#61538;-glucanasa va resultar en l'obtenció d'una proteïna plegada que encara manté certa activitat hidrolasa del &#61538;-glucà. Tot i això, no s'observà activitat o especificitat similar a la xiloglucà endotransglicosilasa. A partir d'aquí, es realitzaren mutacions puntuals a diferents punts de les fulles &#61538; que formen l'escletxa del lloc d'unió de l'enzim per assemblar-se als residus del PttXET16A. La proteïna quimèrica final tampoc presentava activitat XET ni &#61538;-glucanasa. L'anàlisi de l'estructura per cristal·lografia de raigs X revelà una major reorganització estructural de l'esperada proveint el nou enzim d'un clar espai intern que obra moltes més portes a l'enginyeria de l'enzim. / Con la finalidad de entender y modificar la pared celular secundaria de las plantas, se fundó el grupo Enzyme Discovery in Hibrid Aspen for Fibern Engineering (EDEN) compuesto por nueve laboratorios con la financiación de la Comisión Europea. El principal objetivo de la búsqueda del grupo EDEN es ingeniar genéticamente la estructura de fibras para producir árboles transgénicos con propiedades modificadas para las industrias de la pulpa y el papel. En el marco de este proyecto, se seleccionó el Populus tremula x tremuloides xiloglucán endotransglicosilasa (PttXET16A) para estudiar en profundidad su actividad transglicosilasa catalizando la rotura y la reconnexión de moléculas de xiloglucán, el cual parece estar involucrado en la morfogénesis de la pared celular secundaria. De esta forma, se intentó crear una familia 16 de híbridos de la enzima activa con carbohidratos &#61538;-glucanasa/XET con la finalidad de diseñar una enzima quimérica con una o más de las propiedades siguientes alteradas: especificidad, actividad y/o estabilidad. Las dos enzimas, Bacillus licheniformis 1,3-1,4-&#61538;-glucanasa y Populus tremula x tremuloides xiloglucà endotransglicosilasa, son miembros de la misma familia enzimática y tienen una gran homología en sus estructuras en 3-dimensiones. Aún así, estas enzimas presentan diferentes actividades, una tiene actividad hidrolasa y la otra, transferasa; diferentes especificidades, una acepta sólo sustratos glicosílicos lineales mientras la otra, sustratos ramificados; y diferentes estabilidades. La construcción de una enzima híbrida representa un reto dentro de la investigación con la finalidad de entender qué características físicas de las dos enzimas se atribuyen al modelo específico de la actividad y especificidad observada. La extracción del lazo más grande de la 1,3-1,4-&#61538;-glucanasa resultó en la obtención de una proteína plegada que todavía mantiene cierta actividad hidrolasa del &#61538;-glucán. Aún así, no se observó actividad o especificidad similar a la xiloglucán endotransglicosilasa. A partir de este punto, se realizaron mutaciones puntuales a diferentes puntos de las hojas &#61538; que forman la brecha del lugar de unión de la enzima por asemejarse a los residuos del PttXET16A. La proteína quimérica final tampoco presentaba actividad XET ni &#61538;-glucanasa. El análisis de la estructura por cristalografía de rayos X reveló una mayor reorganización estructural de la esperada proveyendo la nueva enzima de un claro espacio interno que obre muchas más puertas a la ingeniería de la enzima.

Effectively treating infectious diseases often requires a multi-step approach to target different components involved in disease pathogenesis. Similarly, the COVID-19 pandemic has become a global health crisis that requires a comprehensive understanding of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2) infection to develop effective therapeutics. One potential strategy to instill greater immune protection against COVID-19 is boosting the innate immune system. This boosting, termed trained immunity, employs immune system modulators to train innate immune cells to produce an enhanced, non-specific immune response upon reactivation following exposure to pathogens, a process that has been studied in the context of and clinical studies prior to the COVID-19 pandemic. Evaluation of the underlying pathways that are essential to inducing protective trained immunity will provide insight into identifying potential therapeutic targets that may alleviate the COVID-19 crisis. Here we review multiple immune training agents, including Bacillus Calmette-Guérin (BCG), β-glucan, and lipopolysaccharide (LPS), and the two most popular cell types involved in trained immunity, monocytes and natural killer (NK) cells, and compare the signaling pathways involved in innate immunity. Additionally, we discuss COVID-19 trained immunity clinical trials, emphasizing the potential of trained immunity to fight SARS-CoV-2 infection. Understanding the mechanisms by which training agents activate innate immune cells to reprogram immune responses may prove beneficial in developing preventive and therapeutic targets against COVID-19.