Magdalena Escorcia

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite responsible for toxoplasmosis, a disease with significant health implications for humans and animals. The surface antigen 1 (SAG1) of T. gondii is a major immunodominant protein that facilitates host cell invasion, making it an ideal target for diagnostic and therapeutic interventions. Immunoglobulin Y (IgY), the primary antibody in avian species, offers unique advantages over mammalian IgG, including easier animal care, lower costs, high-yield production, and potential passive immunization. Objectives: This study aimed to induce, purify, and characterize IgY antibodies targeting T. gondii SAG1 from hen egg yolks. Methods: The coding region of the mature portion of T. gondii SAG1 was amplified by PCR, cloned into the pET32a(+) vector for heterologous expression in E. coli. The recombinant SAG1 (rSAG1) was purified by affinity chromatography and used to immunize hens. IgY was extracted from egg yolks using PEG. SDS-PAGE and spectrophotometry were used to evaluate purity and concentration. By ELISA, Western blot, and flow cytometry, the specificity of IgY was assessed against recombinant and endogenous, native, and denatured SAG1. Results: Purified IgY demonstrated strong recognition of both recombinant and native SAG1 in ELISA and Western blot, and against T. gondii tachyzoites by flow cytometry. Conclusions: SAG1-specific IgY was produced in a pure form; it could be helpful in research, diagnosis, and treatment at low costs on a larger production scale, with minimal animal harm.

The high pathogenicity avian influenza virus H5N1, which first emerged in the winter of 2021, has resulted in multiple outbreaks across the American continent through the summer of 2023 and they continue based on early 2025 records, presenting significant challenges for global health and food security. The viruses causing the outbreaks belong to clade 2.3.4.4b, which are descendants of the lineage A/Goose/Guangdong/1/1996 (Gs/Gd) through genetic reassortments with several low pathogenicity avian influenza viruses present in populations of Anseriformes and Charadriiformes orders. This review addresses these issues by thoroughly analysing available epidemiological databases and specialized literature reviews. This project explores the mechanisms behind the resurgence of the H5N1 virus. It provides a comprehensive overview of the origin, timeline and factors contributing to its prevalence among wild bird populations on the American continent.

Since the discovery of antibodies by Emil Von Behring and Shibasaburo Kitasato during the 19th century, their potential for use as biotechnological reagents has been exploited in different fields, such as basic and applied research, diagnosis, and the treatment of multiple diseases. Antibodies are relatively easy to obtain from any species with an adaptive immune system, but birds are animals characterized by relatively easy care and maintenance. In addition, the antibodies they produce can be purified from the egg yolk, allowing a system for obtaining them without performing invasive practices, which favors the three “rs” of animal care in experimentation, i.e., replacing, reducing, and refining. In this work, we carry out a brief descriptive review of the most outstanding characteristics of so-called “IgY technology” and the use of IgY antibodies from birds for basic experimentation, diagnosis, and treatment of human beings and animals.

Chicken meat is a food of high nutritional quality; its production requires birds called broilers breeders and looking after all aspects that influence their reproductive capacity. An ongoing controversy exists among researchers related to the weight of the rooster and its fertilization capacity. By histological and biochemical tests, the association between weight and age with oxidant damage, testicular parenchyma and antioxidant capacity was evaluated in Ross 308 roosters. Testicular integrity was assessed by histological analysis, oxidative stress was determined by malondialdehyde content, non-enzymatic antioxidant capacity was determined by oxygen radical absorbance capacity assay and enzymatic antioxidant capacity through glutathione peroxidase, glutathione reductase and glutathione-S-transferase activities. Histological analysis showed vacuolization of the epithelium from the seminiferous tubules. A significant negative association was observed between malondialdehyde and the deterioration of the integrity of the seminiferous epithelium, as well as between age and integrity of the seminiferous epithelium. It became evident that oxidative damage directly affects the quality of testicular parenchyma. Weight and age were not associated with the antioxidant enzymes activities, but with non-enzymatic capacity. The data obtained suggest that weight is not the most important factor that influences the fertility of the rooster.

During the 2012 highly pathogenic avian influenza outbreak in Mexico caused by the H7N3 subtype, infection led to the death of approximately 22 million laying hens. Thus, poultry farmers were faced with a challenge to ensure the continued commercial flow of eggs. In addition to implementing established sanitary protocols and vaccination programs, forced moulting management was utilized in the affected areas. This strategy guaranteed the maintenance of egg production in the quarantined areas by decreasing the mortality of the infected flock while re-stimulating egg production. To understand how forced moulting reduced mortality of the infected birds, we examined the distribution of the avian influenza receptor in the oviduct of hens subjected to forced moulting. We tested if changes in the reproductive tract caused by forced moulting generated a decrease in the expression of the specific virus receptor in the cell membranes. Host susceptibility to the influenza virus was determined by the presence of these specific receptors. We utilized immunofluorescence of the Maackia amurensis lectin to identify the presence of the virus receptor in histological sections of the oviducts of birds in egg production and birds undergoing forced moulting. The results showed the presence and distribution of the receptors for avian influenza. A strong signal of the receptor was observed in the histological sections of the oviducts of birds in egg production. Conversely, the signal was low in the oviducts of birds undergoing forced moulting. These results demonstrate a decrease in the number of receptors of birds subjected to forced moulting. A lack of receptors would affect virus infection and replication as well as virus-induced damage in the oviduct, which may help explain the observation in the field that birds infected with avian influenza and subjected to forced moulting have decreased mortality.A. Abundant amount of influenza-like receptors, labelled with apple-green fluorescence, on the apical region of the ciliated cylindrical pseudostratifiedepithelium of the uterine region of healthy hens in production. Bar: 100 μm.

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Background: Highly pathogenic avian influenza A(H5N1) viruses are an important health problem in many Asian and African countries. The current increase in human cases demonstrates that influenza A(H5N1) is still a significant global pandemic threat. Many health organizations have recognized the need for new strategies to improve influenza global surveillance. Specifically, the World Health Organization through the global technical consultation for influenza surveillance have called for a detailed picture of the current limitations, especially at the nation level, to evaluate, standardize and strength reporting systems. The main goal of our study is to demonstrate the value of genetic surveillance as part of a strategic surveillance plan. As a proof of concept, we evaluated the current situation of influenza A(H5N1) in Asian and Africa. Results: Our analysis revealed a power-law distribution in the number of sequences of A(H5N1) viruses analyzed and/or reported to influenza surveillance networks. The majority of the Asian and African countries at great risk of A(H5N1) infections have very few (approximately three orders of magnitude) sequenced A(H5N1) viruses (e.g. hemagglutinin genes). This suggests that countries under pandemic alert for avian influenza A(H5N1) have very limited participation (e.g. data generation, genetic analysis and data share) in avian influenza A(H5N1) surveillance. More important, this study demonstrates the usefulness of influenza genetic surveillance to detect emerging pandemic threat viruses. Conclusions: Our study reveals that some countries suffering from human cases of avian influenza have limited participation (e.g. genetic surveillance or data share) with global surveillance networks. Also, we demonstrate that the implementation of genetic surveillance programs could increase and strengthen worldwide epidemic and pandemic preparedness. We hope that this work promotes new discussions between policy makers and health surveillance organizations to improve current methodologies and regulations.

Background: Serologic surveillance of Avian Influenza (AI) viruses is carried out by the hemagglutination inhibition (HI) test using reference reagents. This method is recommended by animal health organizations as a standard test to detect antigenic differences (subtypes) between circulating influenza virus, vaccine- and/or reference- strains. However, significant discrepancies between reference antisera and field isolates have been observed during serosurveillance of influenza A viruses in pig and poultry farms. The objective of this study was to examine the effects of influenza virus genetic and antigenic drift on serologic testing using standard HI assays and reference reagents. Low pathogenic AI H5N2 viruses isolated in Mexico between 1994 and 2008 were used for phylogenetic analysis of AI hemagglutinin genes and for serologic testing using antisera produced with year-specific AI virus isolates. Results: Phylogenetic analysis revealed significant divergence between early LPAI H5N2 viruses (1994 - 1998) and more recent virus field isolates (2002 - 2008). Results of the HI test were markedly influenced by the selection of the AI H5N2 virus (year of isolation) used as reference antigen for the assay. These analyses indicate that LPAI H5N2 viruses in Mexico are constantly undergoing genetic drift and that serosurveillance of AI viruses is significantly influenced by the antigen or antisera used for the HI test. Conclusions: Reference viral antigens and/or antisera need to be replaced constantly during surveillance of AI viruses to keep pace with the AI antigenic drift. This strategy should improve the estimation of antigenic differences between circulating AI viruses and the selection of suitable vaccine strains.

Human -defensin 3 has received great interest for possible pharmaceutical applications. To characterize the biology of this antimicrobial peptide, the mouse -defensin 14 has been selected as a prototypical model. This report provides definite evidence of true orthology between these defensins and reveals molecular diversity of a mammalian specific domain responsible for their antimicrobial activity. Specifically, this analysis demonstrates that eleven amino acid residues of the antimicrobial domain have been mutated by positive selection to confer protein niche specialization. These data support the notion that natural selection acts as evolutionary force driving the proliferation and diversification of defensins and introduce a novel strategy for the design of more effective antibiotics.