Nonsteroidal anti-inflammatory drugs restore immune function to respiratory syncytial virus in geriatric cotton rats (Sigmodon hispidus)

Respiratory syncytial virus (RSV) infection is not only a childhood disease, but also a serious health risk for the elderly. We investigated in cotton rats how age affected viral clearance, immune responses, and whether pharmacological intervention was beneficial. Our results demonstrated that in geriatric animals, virus grew to similar titers, but with delayed clearance, compared to adult animals. After primary infection with RSV, geriatric animals were susceptible to secondary infection and results indicated a defective humoral immune response. Depletion of cytotoxic T lymphocytes (CTL) during primary infection delayed clearance, indicating the necessary role of CTL. Pharmacological intervention through nonsteroidal anti-inflammatory ibuprofen resulted in faster viral clearance and complete protection after immunization. In addition, the CTL response in the presence of ibuprofen seemed to be restored. It appears that in geriatric animals, immune functions are not as effective as in adult animals and that anti-inflammatory therapy may restore effective immune function.

Pulmonary function analysis in cotton rats after respiratory syncytial virus infection

The cotton rat (Sigmodon hispidus) is an excellent small animal model for human respiratory viral infections such as human respiratory syncytial virus (RSV) and human metapneumovirus (HMPV). These respiratory viral infections, as well as other pulmonary inflammatory diseases such as asthma, are associated with lung mechanic disturbances. So far, the pathophysiological effects of viral infection and allergy on cotton rat lungs have not been measured, although this information might be an important tool to determine the efficacy of vaccine and drug candidates. To characterize pulmonary function in the cotton rat, we established forced oscillation technique in uninfected, RSV infected and HDM sensitized cotton rats, and characterized pulmonary inflammation, mucus production, pulmonary edema, and oxygenation. There was a gender difference after RSV infection, with females demonstrating airway hyper-responsiveness while males did not. Female cotton rats 2dpi had a mild increase in pulmonary edema (wet: dry weight ratios). At day 4 post infection, female cotton rats demonstrated mild pulmonary inflammation, no increase in mucus production or reduction in oxygenation. Pulmonary function was not significantly impaired after RSV infection. In contrast, cotton rats sensitized to HDM demonstrated airway hyper-responsiveness with a significant increase in pulmonary inflammation, increase in baseline tissue damping, and a decrease in baseline pulmonary compliance. In summary, we established baseline data for forced oscillation technique and other respiratory measures in the cotton rat and used it to analyze respiratory diseases in cotton rats.

Cause and Treatment of Exophthalmos in Aged Cotton Rats (Sigmodon hispidus)

Aged cotton rats (Sigmodon hispidus) from an established breeding colony displayed signs of spontaneous exophthalmos. Of a total of 118 colony animals that were older than 6 mo of age, 37 (31%) displayed signs of exophthalmos. These rats were clinically healthy and had no other signs of disease. Ophthalmic exams, molecular and microbiologic testing, and histopa- thology were performed to determine the cause of the exophthalmos and to provide appropriate treatment. Environmental monitoring records were also reviewed for vivarium rooms in which the cotton rats were housed. Histopathology findings supported that the exophthalmos in these cotton rats was secondary to retro-orbital thrombosis associated with cardiomyopathy. The exophthalmic eyes were treated by either removal of the affected eye (enucleation) or surgical closure of the eyelids (temporary tarsorraphy). Enucleation of the exophthalmic eye was the best intervention for these aged cotton rats. These findings demonstrate the potential for a high incidence of ocular problems occurring secondary to cardiomyopathy in aged cotton rats. Enucleation as a therapeutic intervention for exophthalmic eyes in aged cotton rats prolongs the morbidity-free time span during which these aged animals can be used experimentally.

Effective in Vivo Targeting of Influenza Virus through a Cell-Penetrating/Fusion Inhibitor Tandem Peptide Anchored to the Plasma Membrane

The impact of influenza virus infection is felt each year on a global scale when approximately 5-10% of adults and 20-30% of children globally are infected. While vaccination is the primary strategy for influenza prevention, there are a number of likely scenarios for which vaccination is inadequate, making the development of effective antiviral agents of utmost importance. Anti-influenza treatments with innovative mechanisms of action are critical in the face of emerging viral resistance to the existing drugs. These new antiviral agents are urgently needed to address future epidemic (or pandemic) influenza and are critical for the immune-compromised cohort who cannot be vaccinated. We have previously shown that lipid tagged peptides derived from the C-terminal region of influenza hemagglutinin (HA) were effective influenza fusion inhibitors. In this study, we modified the influenza fusion inhibitors by adding a cell penetrating peptide sequence to promote intracellular targeting. These fusion-inhibiting peptides self-assemble into ∼15-30 nm nanoparticles (NPs), target relevant infectious tissues in vivo, and reduce viral infectivity upon interaction with the cell membrane. Overall, our data show that the CPP and the lipid moiety are both required for efficient biodistribution, fusion inhibition, and efficacy in vivo.