Anti-hemagglutinin monomeric nanobody provides prophylactic immunity against H1 subtype influenza A viruses.

Influenza viruses constitute a major threat to human health globally. The viral surface glycoprotein hemagglutinin (HA) is the immunodominant antigen, contains the site for binding to the cellular receptor (RBS), and it is the major target of neutralizing antibody responses post-infection. We developed llama-derived single chain antibody fragments (VHHs) specific for type A influenza virus. Four VHHs were identified and further characterized. VHH D81 bound residues in the proximity of the C-terminal region of HA1 of H1 and H5 subtypes, and showed weak neutralizing activity, whereas VHH B33 bound residues in the proximity of the N-terminal region of the HA's stem domain (HA2) of H1, H5, and H9 subtypes, and showed no neutralizing activity. Of most relevance, VHHs E13 and G41 recognized highly conserved conformational epitopes on the H1 HA's globular domain (HA1) and showed high virus neutralizing activity (ranging between 0.94 to 0.01µM), when tested against several human H1N1 isolates. Additionally, E13 displayed abrogated virus replication of a panel of H1N1 strains spanning over 80 years of antigenic drift and isolated from human, avian, and swine origin. Interestingly, E13 conferred protection in vivo at a dose as low as 0.05 mg/kg. Mice treated with E13 intranasally resulted in undetectable virus challenge loads in the lungs at day 4 post-challenge. The transfer of sterilizing pan-H1 immunity, by a dose in the range of micrograms given intranasally, is of major significance for a monomeric VHH and supports the further development of E13 as an immunotherapeutic agent for the mitigation of influenza infections.

Serological Responses of Guinea Pigs and Heifers to Eight Different BoAHV-1 Vaccine Formulations.

Bovine alphaherpesvirus 1 (BoAHV-1) infection affects the production and reproductive performance of dairy and beef livestock, resulting in considerable economic losses. In addition to biosecurity measures, vaccination programs are effective strategies for controlling and preventing BoAHV-1 infection and transmission. We evaluated the serological immune response against BoAHV-1 induced by eight different formulations of commercial vaccines: three modified live vaccines and five killed vaccines containing BoAHV type 1 or types 1 and 5. In the first experiment, 50 BoAHV-1-seronegative guinea pigs were assigned to eight groups; each individual in the treatment groups received two doses (one-fifth of the bovine dose). The second experiment was conducted using 29 crossbred Holstein × Gir heifers in four groups of six to nine animals each. The serological immune response against BoAHV-1 was measured using virus neutralization and enzyme-linked immunosorbent assays to measure the total IgG against BoAHV. We evaluated the effects of the vaccine, time, and interaction of the vaccine and time on neutralizing antibodies against BoAHV-1. Killed vaccines produced low levels of antibodies against BoAHV-1, whereas modified live vaccines produced high levels of antibodies capable of providing neutralizing titers in the vaccinated animals, with the thermosensitive modified live vaccine showing the highest levels of antibodies.

First evaluation of the impact of a targeted subunit vaccine against bovine viral diarrhea virus in feedlot cattle.

Bovine respiratory disease (BRD) is a serious health and economic problem in the beef industry, which is often associated with transportation and caused by different pathogens. In this study, we evaluated the effect of a novel subunit targeted vaccine against bovine viral diarrhea virus (BVDV) in feedlot cattle, a major viral agent of BRD. The core of this novel vaccine is the fusion of the BVDV structural glycoprotein, E2, to a single-chain antibody, APCH, together termed, APCH-E2. The APCH antibody targets the E2 antigen to the major histocompatibility type II molecule (MHC-II) present in antigen-presenting cells. To evaluate the vaccine, 2,992 animals were randomly allocated into two groups, control group (N = 1,491) and treatment group (N = 1,501). Animals of both groups received the routine sanitary plan: two doses of clostridial, respiratory, and rabies vaccines. Animals within the treatment group also received two doses of a targeted subunit vaccine against BVDV. Serum samples were taken on the day of the first inoculation (T0) and 90 d later (T90). Viral circulation was monitored using an anti-P80 ELISA (virus-specific) and immune response was evaluated by anti-E2 ELISA (detects virus and vaccine immune responses). Only animals treated for respiratory disease were considered positive cases of BRD. Results demonstrate that the control group had significantly more animals treated for BRD cases compared to the treatment group (5.9% vs. 3.7%, P = 0.02). The control group had a greater number of animals positive for anti-P80 antibodies and significantly fewer animals positive for anti-E2 antibodies compared to the treatment group (69% vs. 61% and 71% vs. 99%, respectively, P = 0.003), consistent with natural viral circulation within this group. The treatment group, conversely, had fewer animals positive for anti-P80 antibodies and a greater number of animals positive for anti-E2 antibodies, consistent with a robust vaccine-induced antibody response and a reduction of the BVDV circulation within this group. The data indicate the new subunit targeted vaccine induced greater anti-E2 antibodies and reduced the amount of BVD virus circulation within the treatment group leading to a fewer number of animals needing to be treated for BRD.

SARS-CoV-2 Specific Nanobodies Neutralize Different Variants of Concern and Reduce Virus Load in the Brain of h-ACE2 Transgenic Mice.

Since the beginning of the COVID-19 pandemic, there has been a significant need to develop antivirals and vaccines to combat the disease. In this work, we developed llama-derived nanobodies (Nbs) directed against the receptor binding domain (RBD) and other domains of the Spike (S) protein of SARS-CoV-2. Most of the Nbs with neutralizing properties were directed to RBD and were able to block S-2P/ACE2 interaction. Three neutralizing Nbs recognized the N-terminal domain (NTD) of the S-2P protein. Intranasal administration of Nbs induced protection ranging from 40% to 80% after challenge with the WA1/2020 strain in k18-hACE2 transgenic mice. Interestingly, protection was associated with a significant reduction in virus replication in nasal turbinates and a reduction in virus load in the brain. Employing pseudovirus neutralization assays, we identified Nbs with neutralizing capacity against the Alpha, Beta, Delta, and Omicron variants, including a Nb capable of neutralizing all variants tested. Furthermore, cocktails of different Nbs performed better than individual Nbs at neutralizing two Omicron variants (B.1.529 and BA.2). Altogether, the data suggest the potential of SARS-CoV-2 specific Nbs for intranasal treatment of COVID-19 encephalitis.

Heterologous booster with a novel formulation containing glycosylated trimeric S protein is effective against Omicron.

In this study, we evaluated the efficacy of a heterologous three-dose vaccination schedule against the Omicron BA.1 SARS-CoV-2 variant infection using a mouse intranasal challenge model. The vaccination schedules tested in this study consisted of a primary series of 2 doses covered by two commercial vaccines: an mRNA-based vaccine (mRNA1273) or a non-replicative vector-based vaccine (AZD1222/ChAdOx1, hereafter referred to as AZD1222). These were followed by a heterologous booster dose using one of the two vaccine candidates previously designed by us: one containing the glycosylated and trimeric spike protein (S) from the ancestral virus (SW-Vac 2µg), and the other from the Delta variant of SARS-CoV-2 (SD-Vac 2µg), both formulated with Alhydrogel as an adjuvant. For comparison purposes, homologous three-dose schedules of the commercial vaccines were used. The mRNA-based vaccine, whether used in heterologous or homologous schedules, demonstrated the best performance, significantly increasing both humoral and cellular immune responses. In contrast, for the schedules that included the AZD1222 vaccine as the primary series, the heterologous schemes showed superior immunological outcomes compared to the homologous 3-dose AZD1222 regimen. For these schemes no differences were observed in the immune response obtained when SW-Vac 2µg or SD-Vac 2µg were used as a booster dose. Neutralizing antibody levels against Omicron BA.1 were low, especially for the schedules using AZD1222. However, a robust Th1 profile, known to be crucial for protection, was observed, particularly for the heterologous schemes that included AZD1222. All the tested schedules were capable of inducing populations of CD4 T effector, memory, and follicular helper T lymphocytes. It is important to highlight that all the evaluated schedules demonstrated a satisfactory safety profile and induced multiple immunological markers of protection. Although the levels of these markers were different among the tested schedules, they appear to complement each other in conferring protection against intranasal challenge with Omicron BA.1 in K18-hACE2 mice. In summary, the results highlight the potential of using the S protein (either ancestral Wuhan or Delta variant)-based vaccine formulation as heterologous boosters in the management of COVID-19, particularly for certain commercial vaccines currently in use.

Nanobodies against SARS-CoV-2 reduced virus load in the brain of challenged mice and neutralized Wuhan, Delta and Omicron Variants.

In this work, we developed llama-derived nanobodies (Nbs) directed to the receptor binding domain (RBD) and other domains of the Spike (S) protein of SARS-CoV-2. Nanobodies were selected after the biopanning of two VHH-libraries, one of which was generated after the immunization of a llama (lama glama) with the bovine coronavirus (BCoV) Mebus, and another with the full-length pre-fused locked S protein (S-2P) and the RBD from the SARS-CoV-2 Wuhan strain (WT). Most of the neutralizing Nbs selected with either RBD or S-2P from SARS-CoV-2 were directed to RBD and were able to block S-2P/ACE2 interaction. Three Nbs recognized the N-terminal domain (NTD) of the S-2P protein as measured by competition with biliverdin, while some non-neutralizing Nbs recognize epitopes in the S2 domain. One Nb from the BCoV immune library was directed to RBD but was non-neutralizing. Intranasal administration of Nbs induced protection ranging from 40% to 80% against COVID-19 death in k18-hACE2 mice challenged with the WT strain. Interestingly, protection was not only associated with a significant reduction of virus replication in nasal turbinates and lungs, but also with a reduction of virus load in the brain. Employing pseudovirus neutralization assays, we were able to identify Nbs with neutralizing capacity against the Alpha, Beta, Delta and Omicron variants. Furthermore, cocktails of different Nbs performed better than individual Nbs to neutralize two Omicron variants (B.1.529 and BA.2). Altogether, the data suggest these Nbs can potentially be used as a cocktail for intranasal treatment to prevent or treat COVID-19 encephalitis, or modified for prophylactic administration to fight this disease.

Development of an IgY-Based Treatment to Control Bovine Coronavirus Diarrhea in Dairy Calves.

Bovine Coronavirus (BCoV) is a major pathogen associated with neonatal calf diarrhea. Standard practice dictates that to prevent BCoV diarrhea, dams should be immunized in the last stage of pregnancy to increase BCoV-specific antibody (Ab) titers in serum and colostrum. For the prevention to be effective, calves need to suck maternal colostrum within the first six to twelve hours of life before gut closure to ensure a good level of passive immunity. The high rate of maternal Ab transfer failure resulting from this process posed the need to develop alternative local passive immunity strategies to strengthen the prevention and treatment of BCoV diarrhea. Immunoglobulin Y technology represents a promising tool to address this gap. In this study, 200 laying hens were immunized with BCoV to obtain spray-dried egg powder enriched in specific IgY Abs to BCoV on a large production scale. To ensure batch-to-batch product consistency, a potency assay was statistically validated. With a sample size of 241, the BCoV-specific IgY ELISA showed a sensitivity and specificity of 97.7% and 98.2%, respectively. ELISA IgY Abs to BCoV correlated with virus-neutralizing Ab titers (Pearson correlation, R2 = 0.92, p < 0.001). Most importantly, a pilot efficacy study in newborn calves showed a significant delay and shorter duration of BCoV-associated diarrhea and shedding in IgY-treated colostrum-deprived calves. Calves were treated with milk supplemented with egg powder (final IgY Ab titer to BCoV ELISA = 512; VN = 32) for 14 days as a passive treatment before a challenge with BCoV and were compared to calves fed milk with no supplementation. This is the first study with proof of efficacy of a product based on egg powder manufactured at a scale that successfully prevents BCoV-associated neonatal calf diarrhea.

Immunological study of COVID-19 vaccine candidate based on recombinant spike trimer protein from different SARS-CoV-2 variants of concern.

The emergency of new SARS-CoV-2 variants that feature increased immune escape marks an urgent demand for better vaccines that will provide broader immunogenicity. Here, we evaluated the immunogenic capacity of vaccine candidates based on the recombinant trimeric spike protein (S) of different SARS-CoV-2 variants of concern (VOC), including the ancestral Wuhan, Beta and Delta viruses. In particular, we assessed formulations containing either single or combined S protein variants. Our study shows that the formulation containing the single S protein from the ancestral Wuhan virus at a concentration of 2µg (SW2-Vac 2µg) displayed in the mouse model the highest IgG antibody levels against all the three (Wuhan, Beta, and Delta) SARS-CoV-2 S protein variants tested. In addition, this formulation induced significantly higher neutralizing antibody titers against the three viral variants when compared with authorized Gam-COVID-Vac-rAd26/rAd5 (Sputnik V) or ChAdOx1 (AstraZeneca) vaccines. SW2-Vac 2µg was also able to induce IFN-gamma and IL-17, memory CD4 populations and follicular T cells. Used as a booster dose for schedules performed with different authorized vaccines, SW2-Vac 2µg vaccine candidate also induced higher levels of total IgG and IgG isotypes against S protein from different SARS-CoV-2 variants in comparison with those observed with homologous 3-dose schedule of Sputnik V or AstraZeneca. Moreover, SW2-Vac 2µg booster induced broadly strong neutralizing antibody levels against the three tested SARS-CoV-2 variants. SW2-Vac 2µg booster also induced CD4+ central memory, CD4+ effector and CD8+ populations. Overall, the results demonstrate that SW2-Vac 2 µg is a promising formulation for the development of a next generation COVID-19 vaccine.

Development of Nanobodies against Mal de Río Cuarto virus major viroplasm protein P9-1 for diagnostic sandwich ELISA and immunodetection.

Mal de Río Cuarto virus (MRCV) is a member of the genus Fijivirus of the family Reoviridae that causes a devastating disease in maize and is persistently and propagatively transmitted by planthopper vectors. Virus replication and assembly occur within viroplasms formed by viral and host proteins. This work describes the isolation and characterization of llama-derived Nanobodies (Nbs) recognizing the major viral viroplasm component, P9-1. Specific Nbs were selected against recombinant P9-1, with affinities in the nanomolar range as measured by surface plasmon resonance. Three selected Nbs were fused to alkaline phosphatase and eGFP to develop a sandwich ELISA test which showed a high diagnostic sensitivity (99.12%, 95% CI 95.21-99.98) and specificity (100%, 95% CI 96.31-100) and a detection limit of 0.236 ng/ml. Interestingly, these Nanobodies recognized different P9-1 conformations and were successfully employed to detect P9-1 in pull-down assays of infected maize extracts. Finally, we demonstrated that fusions of the Nbs to eGFP and RFP allowed the immunodetection of virus present in phloem cells of leaf thin sections. The Nbs developed in this work will aid the study of MRCV epidemiology, assist maize breeding programs, and be valuable tools to boost fundamental research on viroplasm structure and maturation.

Development of a platform process for the production and purification of single-domain antibodies.

Single-domain antibodies (sdAbs) offer the affinity and therapeutic value of conventional antibodies, with increased stability and solubility. Unlike conventional antibodies, however, sdAbs do not benefit from a platform manufacturing process. While successful production of a variety of sdAbs has been shown in numerous hosts, purification methods are often molecule specific or require affinity tags, which generally cannot be used in clinical manufacturing due to regulatory concerns. Here, we have developed a broadly applicable production and purification process for sdAbs in Komagataella phaffii (Pichia pastoris) and demonstrated the production of eight different sdAbs at a quality appropriate for nonclinical studies. We developed a two-step, integrated purification process without the use of affinity resins and showed that modification of a single process parameter, pH of the bridging buffer, was required for the successful purification of a variety of sdAbs. Further, we determined that this parameter can be predicted based only on the biophysical characteristics of the target molecule. Using these methods, we produced nonclinical quality sdAbs as few as 5 weeks after identifying the product sequence. Nonclinical studies of three different sdAbs showed that molecules produced using our platform process conferred protection against viral shedding of rotavirus or H1N1 influenza and were equivalent to similar molecules produced in Escherichia coli and purified using affinity tags.

A novel MHC-II targeted BVDV subunit vaccine induces a neutralizing immunological response in guinea pigs and cattle.

Bovine viral diarrhoea virus (BVDV) is a major cause of economic loss in the cattle industry, worldwide. Infection results in reduced productive performance, growth retardation, reduced milk production and increased susceptibility to other diseases leading to early culling of animals. There are two primary methods used to control the spread of BVDV: the elimination of persistently infected (PI) animals and vaccination. Currently, modified live or inactivated vaccines are used in BVDV vaccination programmes, but there are safety risks or insufficient protection, respectively, with these vaccines. Here, we report the development and efficacy of the first targeted subunit vaccine against BVDV. The core of the vaccine is the fusion of the BVDV structural protein, E2, to a single-chain antibody, APCH, together termed, APCH-E2. The APCH antibody targets the E2 antigen to the major histocompatibility type II molecule (MHC-II) present on antigen-presenting cells. Industrial production of the vaccine is carried out using the baculovirus expression vector system (BEVS) using single-use manufacturing technologies. This new subunit vaccine induces strong BVDV-specific neutralizing antibodies in guinea pigs and cattle. Importantly, in cattle with low levels of natural BVDV-specific neutralizing antibodies, the vaccine induced strong neutralizing antibody levels to above the protective threshold, as determined by a competition ELISA. The APCH-E2 vaccine induced a rapid and sustained neutralizing antibody response compared with a conventional vaccine in cattle.

Bovine Dendritic Cell Activation, T Cell Proliferation and Antibody Responses to Foot-And-Mouth Disease, Is Similar With Inactivated Virus and Virus Like Particles.

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals that causes severe economic losses in the livestock industry. Currently available vaccines are based on the inactivated FMD virus (FMDV). Although inactivated vaccines have been effective in controlling the disease, they have some disadvantages. Because of these disadvantages, investigations are being made to produce vaccines in low containment facilities. The use of recombinant empty capsids (also referred as Virus Like Particles, VLPs) has been reported to be a promising candidate as a subunit vaccine because it avoids the use of virus in the vaccine production and conserves the conformational epitopes of the virus. Mignaqui and collaborators have produced recombinant FMDV empty capsids from serotype A/ARG/2001 using a scalable technology in mammalian cells that elicited a protective immunity against viral challenge in a mouse model. However, further evaluation of the immune response elicited by these VLPs in cattle is required. In the present work we compare the effect that VLPs or inactivated FMDV has on bovine dendritic cells and the humoral response elicited in cattle after a single vaccination.

Foot-and-Mouth Disease: Optimization, Reproducibility, and Scalability of High-Yield Production of Virus-Like Particles for a Next-Generation Vaccine.

Inactivated Foot-and-Mouth Disease (FMD) vaccine has proven to be effective in the control of the disease. However, its production has some disadvantages, including the costly biosafety facilities required for the production of huge amounts of growing live virus, the need of an exhaustive purification process to eliminate non-structural proteins of the virus in the final formulations in order to differentiate infected from vaccinated animals and variable local regulatory restrictions to produce and commercialize the vaccine. Thus, a novel vaccine against FMD that overcome these restrictions is desirable. Although many developments have been made in this regard, most of them failed in terms of efficacy or when considering their transferability to the industry. We have previously reported the use of transient gene expression in mammalian cells to produce FMD virus-like particles (VLPs) as a novel vaccine for FMD and demonstrated the immunogenicity of the recombinant structures in animal models. Here, we report the optimization of the production system by assaying different DNA:polyethylenimine concentrations, cell densities, and direct and indirect protocols of transfection. Also, we evaluated the reproducibility and scalability of the technology to produce high yields of recombinant VLPs in a cost-effective and scalable system compatible with industrial tech-transfer of an effective and safe vaccine.

A new passive immune strategy based on IgY antibodies as a key element to control neonatal calf diarrhea in dairy farms.

BACKGROUND: Neonatal diarrhea remains one of the main causes of morbi-mortality in dairy calves under artificial rearing. It is often caused by infectious agents of viral, bacterial, or parasitic origin. Cows vaccination and colostrum intake by calves during the first 6 h of life are critical strategies to prevent severe diarrhea but these are still insufficient. Here we report the field evaluation of a product based on IgY antibodies against group A rotavirus (RVA), coronavirus (CoV), enterotoxigenic Escherichia coli, and Salmonella sp. This product, named IgY DNT, has been designed as a complementary passive immunization strategy to prevent neonatal calf diarrhea. The quality of the product depends on the titers of specific IgY antibodies to each antigen evaluated by ELISA. In the case of the viral antigens, ELISA antibody (Ab) titers are correlated with protection against infection in calves experimentally challenged with RVA and CoV (Bok M, et al., Passive immunity to control bovine coronavirus diarrhea in a dairy herd in Argentina, 2017), (Vega C, et al., Vet Immunol Immunopathol, 142:156-69, 2011), (Vega C, et al., Res Vet Sci, 103:1-10, 2015). To evaluate the efficiency in dairy farms, thirty newborn Holstein calves were randomly assigned to IgY DNT or control groups and treatment initiated after colostrum intake and gut closure. Calves in the IgY DNT group received 20 g of the oral passive treatment in 2 L of milk twice a day during the first 2 weeks of life. Animals were followed until 3 weeks of age and diarrhea due to natural exposure to infectious agents was recorded during all the experimental time. RESULTS: Results demonstrate that the oral administration of IgY DNT during the first 2 weeks of life to newborn calves caused a delay in diarrhea onset and significantly reduced its severity and duration compared with untreated calves. Animals treated with IgY DNT showed a trend towards a delay in RVA infection with significantly shorter duration and virus shedding compared to control calves. CONCLUSIONS: This indicates that IgY DNT is an effective product to complement current preventive strategies against neonatal calf diarrhea in dairy farms. Furthermore, to our knowledge, this is the only biological product available for the prevention of virus-associated neonatal calf diarrhea.

Nanoanticuerpos derivados de llamas: una alternativa innovadora para controlar las diarreas por rotavirus y norovirus humano / Llama-derived nanobodies: an innovative approach to control human rotavirus and norovirus diarrhea

Las diarreas agudas son una de las afecciones más comunes en personas de todas las edades, especialmente en niños menores de 5 años. Rotavirus (RV) es la principal causa de diarrea en niños a nivel mundial seguido por norovirus (NoV). Sin embargo, a partir de la implementación de la vacunación con RV, NoV pasó a tener un rol preponderante en varios países como EEUU y Nicaragua. En Argentina, luego del inicio de la vacunación obligatoria de RV se logró un alto porcentaje de cobertura vacunal y se evidenció un descenso del 10% en la ocurrencia de diarreas agudas en general y un descenso del 50% de las diarreas causadas específicamente por RV, demostrando el éxito rotundo de la intervención. No existen al momento vacunas contra NoV, lo que lleva al desarrollo de otras estrategias de contención. A través del laboratorio INCUINTA del Instituto Nacional de Tecnología Agropecuaria (INTA), se han desarrollado y patentado nanoanticuerpos VHH contra RV y NoV con propiedades que los transforman en excelentes herramientas para el desarrollo de métodos de diagnóstico y para su utilización en estrategias de inmunidad pasiva oral para el tratamiento y prevención de la infección causada por estos agentes virales. Los nanoanticuerpos anti RV fueron utilizados con éxito para el desarrollo de un kit de ELISA nacional validado junto con el Instituto Malbrán que está siendo registrado para su comercialización. Además, demostraron poseer capacidad neutralizante de la infección contra RV in vitro y protección frente a la diarrea y excreción viralen los modelos de ratones lactantes y cerdos gnotobióticos. Los nano anticueroscontra NoV poseen alta afinidad para la detección del virus y fueron capaces de bloquear la unión del virus a los receptores celulares in vitro, demostrando su potencial como moléculas terapéuticas y de diagnóstico. El objetivo final de este desarrollo es completar la triada diagnostico-prevencióntratamiento para el control de las gastroenteritis virales con una tecnología de vanguardia de industria nacional.

Acute diarrhea is a common affection in people ofall ages, especially in children under five years old. Rotavirus (RV) is the major cause of diarrhea in children worldwide followed by norovirus (NoV). However, afterthe introduction of RV vaccine in the vaccination calendar in several countries like the USA and Nicaragua, NoV is having an important role in gastroenteritis incidence. In Argentina, after the introduction of the RV vaccine, high vaccine coverage was reached and the overall acute diarrhea incidence was reduced in a 10% and RV-associated diarrhea was reduced 50%, leading to complete success of the vaccination strategy. At the moment, there are no vaccines against NoV, thus, it is a need to develop therapies to control this disease. INCUINTA has developed and patented two sets of VHH nanobodies against RV and NoV with unique properties that make them suitable for the development of diagnostic tools, as well as to design oral passive immune strategies to preventand treat these two viral infections associated with diarrhea. VHH against rotavirus were able to neutralize RV infection in a suckling mouse model and in a gnotobiotic pig model of human RV infection and disease. Also, they were used to develop an ELISA kit for RV detection in human and animal samples. The ELISA kit was statistically validated in collaboration with the Malbrán Institute and is being registered for commercialization. VHH to NoVs showed high affinity to the virus and blocked the interaction between the virus and histo-blood antigens in target cells in vitro, showing to be a potential tool to detect and treat NoV infection. The final goal of this project is to complete the diagnostic-prevention-treatment triad to control viral gastroenteritis using a vanguard technology made in Argentina.

First detection of Ostreid herpesvirus 1 in wild Crassostrea gigas in Argentina.

Ostreid herpesvirus 1 (OsHV-1) is a DNA virus of the genus Ostreavirus (Malacoherpesviridae family, Herpesvirales order). Worldwide, OsHV-1 and its microvariants have been associated with increased mortality of Pacific oysters, Crassostrea gigas. Adult asymptomatic oysters also have shown a high prevalence of viral infection. As a consequence, surveillance is needed to better describe OsHV-1 diversity, pathogenicity, clinical signs, and geographical distribution. We examined Crassostrea gigas sampled in October 2017 from the inner zone of the Bahía Blanca Estuary, Argentina, and found that 8 of 30 specimens (26.7%) presented macroscopic lesions in mantle tissues. Histological analysis revealed abnormal presentation of mantle epithelial cells and connective tissues. Conventional and real-time PCR conducted on the oyster samples revealed 70% to be positive for presence of OsHV-1 DNA. The nucleotide sequence of the amplicon obtained from one sample using the primer pair IA1/IA2 (targeting ORF 42/43) was 99% identical to OsHV-1 reference as well as µVar strains B and A (KY271630, KY242785.1), sequenced from France and Ireland. This finding represents the first detection of OsHV-1 DNA in a wild population of C. gigas in Argentina in association with gross mantle lesions.

Advances in novel vaccines for foot and mouth disease: focus on recombinant empty capsids.

Foot and mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals, which causes severe economic losses in the livestock industry. Currently available vaccines are based on inactivated FMD virus (FMDV). Although inactivated virus vaccines have proved to be effective in FMD control, they have a number of disadvantages, including the need for high bio-containment production facilities and the lack of induction of immunological memory. Novel FMD vaccines based on the use of recombinant empty capsids have shown promising results. These recombinant empty capsids are attractive candidates because they avoid the use of virus in the production facilities but conserve its complete repertoire of conformational epitopes. However, many of these recombinant empty capsids require time-consuming procedures that are difficult to scale up. Achieving production of a novel and efficient FMD vaccine requires not only immunogenic antigens, but also industrially relevant processes. This review intends to summarize and compare the different strategies already published for the production of FMDV recombinant empty capsids, focusing on large-scale production.

Minimally processed crude leaf extracts of Nicotiana benthamiana containing recombinant foot and mouth disease virus-like particles are immunogenic in mice.

Foot-and-mouth disease (FMD) remains one of the most feared viral diseases affecting cloven-hoofed animals, and results in severe economic losses. Currently available vaccines are based on inactivated FMD virus (FMDV). The use of recombinant FMDV-like particles (VLPs) as subunit vaccines has gained importance because of their immunogenic properties and safety. We evaluated the production of FMD VLPs, via Agrobacterium-mediated transient expression, and the immunogenicity of these structures in mice. Leaves were infiltrated with pEAQ-HT and pRIC 3.0 vectors encoding the capsid precursor P1-2A and the protease 3C. The recombinant protein yield was 3-4 mg/kg of fresh leaf tissue. Both groups of mice immunized with purified VLPs and mice immunized with the crude leaf extract elicited a specific humoral response with similar antibody titers. Thus, minimally processed plant material containing transiently expressed FMD VLPs could be a scalable and cost-effective technology for the production of a recombinant subunit vaccine against FMDV.

Passive immunity to control Bovine coronavirus diarrhea in a dairy herd in Argentina.

Bovine coronavirus (BCoV) is a viral enteric pathogen associated with calf diarrhea worldwide being, in Argentina, mostly detected in dairy husbandry systems. The aim of the present work was to study if maternal IgG1 antibodies (Abs) to BCoV acquired by colostrum intake modulate the development of BCoV infection in calves reared in a dairy farm in Argentina. Thirty Holstein calves were monitored during their first 60 days of age. Animals were classified into two groups depending on their initial BCoV IgG1 Ab titers. The "failure of passive transfer" (FPT) group had significantly lower IgG1 Abs to BCoV than the "acceptable passive transfer" (APT) group of calves (log10 1.98 vs. 3.38 respectively) (p<0.0001). These differences were also observed when the total protein levels in both groups were compared (p=0.0081). Moreover, 71% (5/7) of calves from the FPT group showed IgG1 seroconversion to BCoV compared to 29.4% (5/17) of animals from the APT group. Regarding viral circulation, BCoV was detected in 10% (3/30) of all calves and BCoV IgG1 Ab seroconversion was detected in 42% of the total animals showing that almost half of the calves were infected with BCoV. In conclusion, calves with high titers of specific BCoV IgG1 (≥1024) were mostly protected against viral infection, while animals with low titers of IgG1 (<1024) were mostly infected with BCoV. IgG1 Abs from colostrum origin are critical for prevention of BCoV infection.

A synthetic biology approach for consistent production of plant-made recombinant polyclonal antibodies against snake venom toxins.

Antivenoms developed from the plasma of hyperimmunized animals are the only effective treatment available against snakebite envenomation but shortage of supply contributes to the high morbidity and mortality toll of this tropical disease. We describe a synthetic biology approach to affordable and cost-effective antivenom production based on plant-made recombinant polyclonal antibodies (termed pluribodies). The strategy takes advantage of virus superinfection exclusion to induce the formation of somatic expression mosaics in agroinfiltrated plants, which enables the expression of complex antibody repertoires in a highly reproducible manner. Pluribodies developed using toxin-binding genetic information captured from peripheral blood lymphocytes of hyperimmunized camels recapitulated the overall binding activity of the immune response. Furthermore, an improved plant-made antivenom (plantivenom) was formulated using an in vitro selected pluribody against Bothrops asper snake venom toxins and has been shown to neutralize a wide range of toxin activities and provide protection against lethal venom doses in mice.