Low Dose Pig Anti-Influenza Virus Monoclonal Antibodies Reduce Lung Pathology but Do Not Prevent Virus Shedding

A direct contact pig influenza challenge model for assessing protective efficacy of monoclonal antibodies

Monoclonal antibodies (mAbs) can be used to complement immunization for the therapy of influenza virus infection. We have established the pig, a natural large animal host for influenza A, with many physiological, immunological, and anatomical similarities to humans, as an appropriate model for testing mAbs. We have evaluated the protective efficacy of the strongly neutralizing human anti-hemagglutinin mAb, 2-12C in the pig influenza model. Intravenous administration of recombinant 2-12C reduced virus load and lung pathology, however, it did not prevent virus nasal shedding and, consequently, transmission. This may be because the pigs were directly infected intranasally with a high dose of the H1N1pdm09 virus. To address this, we developed a contact challenge model in which the animals were given 2-12C and one day later co-housed with donor pigs previously infected intra-nasally with H1N1pdm09. 2-12C pre-treatment completely prevented infection. We also administered a lower dose of 2-12C by aerosol to the respiratory tract, but this did not prevent shedding in the direct challenge model, although it abolished lung infection. We propose that the direct contact challenge model of pig influenza may be useful for evaluating candidate mAbs and emerging delivery platforms prior to clinical trials.

Animal models for COVID-19 and tuberculosis

Respiratory infections cause tremendous morbidity and mortality worldwide. Amongst these diseases, tuberculosis (TB), a bacterial illness caused by Mycobacterium tuberculosis which often affects the lung, and coronavirus disease 2019 (COVID-19) caused by the Severe Acute Respiratory Syndrome Coronavirus type 2 (SARS-CoV-2), stand out as major drivers of epidemics of global concern. Despite their unrelated etiology and distinct pathology, these infections affect the same vital organ and share immunopathogenesis traits and an imperative demand to model the diseases at their various progression stages and localizations. Due to the clinical spectrum and heterogeneity of both diseases experimental infections were pursued in a variety of animal models. We summarize mammalian models employed in TB and COVID-19 experimental investigations, highlighting the diversity of rodent models and species peculiarities for each infection. We discuss the utility of non-human primates for translational research and emphasize on the benefits of non-conventional experimental models such as livestock. We epitomize advances facilitated by animal models with regard to understanding disease pathophysiology and immune responses. Finally, we highlight research areas necessitating optimized models and advocate that research of pulmonary infectious diseases could benefit from cross-fertilization between studies of apparently unrelated diseases, such as TB and COVID-19.

Fc-Mediated Functions of Porcine IgG Subclasses

The pig is an important agricultural species and powerful biomedical model. We have established the pig, a large natural host animal for influenza with many physiological similarities to humans, as a robust model for testing the therapeutic potential of monoclonal antibodies. Antibodies provide protection through neutralization and recruitment of innate effector functions through the Fc domain. However very little is known about the Fc-mediated functions of porcine IgG subclasses. We have generated 8 subclasses of two porcine monoclonal anti influenza hemagglutinin antibodies. We characterized their ability to activate complement, trigger cytotoxicity and phagocytosis by immune cells and assayed their binding to monocytes, macrophages, and natural killer cells. We show that IgG1, IgG2a, IgG2b, IgG2c and IgG4 bind well to targeted cell types and mediate complement mediated cellular cytotoxicity (CDCC), antibody dependent cellular cytotoxicity (ADCC) and antibody mediated cell phagocytosis (ADCP). IgG5b and IgG5c exhibited weak binding and variable and poor functional activity. Immune complexes of porcine IgG3 did not show any Fc-mediated functions except for binding to monocytes and macrophages and weak binding to NK cells. Interestingly, functionally similar porcine IgG subclasses clustered together in the genome. These novel findings will enhance the utility of the pig model for investigation of therapeutic antibodies.