David D. Porter

Vaccine-enhanced respiratory syncytial virus disease in cotton rats following immunization with Lot 100 or a newly prepared reference vaccine

A formalin-inactivated respiratory syncytial virus vaccine was used to immunize infants in the mid-1960s; when these children later were naturally infected by the virus they developed markedly accentuated disease, and two died. For the present work, a new batch of vaccine was prepared using the original formula. Administration of either the old or new vaccines resulted in enhanced lesions in immunized cotton rats subsequently challenged with live virus, although administration of the vaccine reduced virus replication by 90%. Animals primed with formalin-inactivated virus and challenged developed markedly accentuated lesions of the same type as in animals undergoing primary or secondary infection. In addition, the animals with the vaccine-enhanced disease developed alveolitis and interstitial pneumonitis, which appear to be specific markers for the vaccine enhancement. The newly prepared vaccine appears suitable as a reference standard for studying the mechanism of vaccine-enhanced disease caused by this virus. Additionally, we reviewed the lesions in the lungs of the two humans who died with the vaccine-enhanced disease in 1967, and found that they were similar to, but more severe than those seen in the cotton rats.

Adenovirus infection in the immunocompromised patient

Illness associated adenovirus infection is described in 15 immunocompromised patients. Patients were immunocompromised by severe underlying disease, immunosuppressive or corticosteroid therapy or by age (prematurity). Evidence of adenovirus infection was obtained by either viral isolation or, in two cases, characteristic adenovirus inclusion bodies at postmortem study. All clinical illness was associated with high fever (temperature greater than 39 degrees C). Eighty per cent of the patients had severe systemic complaints including malaise, lethargy, fatigue and night sweats; a similar number of gastrointestinal symptoms. Pulmonary complaints were described in 11 of 15 cases and included cough (67 per cent) and tachypnea (53 per cent). Roentgenologic evidence of pneumonia was demonstrated in 12 of 15 patients (80 per cent). Elevation of serum hepatic enzyme levels (serum glutamic pyruvic transaminase (SGPT)) occurred in eight of 11 patients (73 per cent) and was moderate to severe (serum glutamic pyruvic transaminase greater than 450 IU/liter) in five of 11 (45 per cent). Nine patients died; seven after a rapid downhill course and two after a prolonged illness. Evidence of adenovirus infection microscopically by autopsy in the lung, liver or both is demonstrated in four patients with fulminant systemic illness. Adenovirus infection should be considered in the etiology of severe overwhelming illness in the immunocompromised host.

Treatment of Respiratory Syncytial Virus Bronchiolitis and Pneumonia in a Cotton Rat Model with Systemically Administered Monoclonal Antibody (Palivizumab) and Glucocorticosteroid

Parenteral treatment of an experimental respiratory syncytial virus (RSV) infection in a cotton rat model with a monoclonal antibody directed against the viral F protein resulted in the clearance of infectious virus within 24 h but had no effect on the pulmonary pathology at 24 h and only a small effect on the pulmonary pathology at 72 h. Treatment with parenteral triamcinolone acetonide dramatically reduced the pathologic lesions of viral bronchiolitis and pneumonia but resulted in the delayed clearance of the virus. The combination of the monoclonal antibody given in a single dose 72 h after infection, combined with 3 daily doses of the corticosteroid starting 72 h after infection, demonstrated both the loss of infectivity and the disappearance of lesions. No rebound of lesions or infectivity was noted. Combined antiviral and anti-inflammatory therapy for RSV disease appears promising.

A Comprehensive Murine Model to Evaluate Topical Vaginal Microbicides: Mucosal Inflammation and Susceptibility to Genital Herpes as Surrogate Markers of Safety

A critical gap in microbicide development is the absence of surrogate safety markers. The objective of the present study was to develop a murine model to examine the mucosal response to microbicides and to assess the functional implication of observed changes. Mice received 14 daily intravaginal doses of nonoxynol-9, PRO 2000, or placebo gel. Nonoxynol-9 induced an inflammatory response characterized by increases in levels of cytokines and chemokines, recruitment of neutrophils and monocytes into the genital tract, and activation of the transcription factors NF- kappa B and activator protein-1. Minimal inflammation was observed in response to 2% PRO 2000. Nonoxynol-9-treated mice were significantly more susceptible to challenge with a low dose of herpes simplex virus type 2; the response of PRO 2000-treated mice was similar to the response to placebo. These findings suggest that PRO 2000 has little deleterious effect on mucosal immunity and, if validated by clinical experiences, support the inclusion of this model in the preclinical evaluation of future candidate microbicides.

Aleutian Disease of Mink

Publisher Summary This chapter presents the immunological parameters of the Aleutian disease of mink. The disease is of special interest because it serves as an excellent model of immune complex disease in which the antigen involved in the immune complexes is known. Viral infection produces a uniquely great antibody response with marked accumulations of plasma cells in the lymph nodes, spleen, kidney, and liver along with marked hyperglobulinemia. Immune complexes are readily demonstrable even by analytical ultracentrifugation, and viral antigen has been demonstrated in the complexes. Severe kidney disease develops in some animals, and viral antibody and antigen have been eluted from the kidney. The glomerular lesions are typical of an immune complex-mediated injury with fine granular deposits along the glomerular basement membrane that can be stained for Ig, C3, and viral antigen. Aleutian disease virus circulates as infectious antigen-antibody complexes in persistently infected mink. Smaller complexes are deposited in the glomeruli and arteries and cause severe and frequently fatal inflammatory lesions. Both the host genotype and the viral genotype influence the severity of Aleutian disease.

Cytokine and chemokine gene expression after primary and secondary respiratory syncytial virus infection in cotton rats

The induction of pro- and anti-inflammatory cytokines and chemokines was studied in the lungs of cotton rats after primary or secondary infection with respiratory syncytial virus (RSV). Increases in messenger RNA (mRNA) levels of all genes analyzed were observed during the course of primary infection. In general, mRNA expression peaked between postinfection days 1 and 4 and returned to near-normal levels by day 10. During secondary infection, the expression of some genes (i.e., interferon [IFN]-gamma and interleukin [IL]-10) began earlier, some (i.e., IL-1beta and macrophage inflammatory protein-1beta) began later, and some (i.e., IL-1beta, IL-10, growth-regulated protein, and tumor necrosis factor-alpha) showed prolonged expression, whereas 2 genes (i.e., IFN-alpha and IL-6) were not expressed. This study presents evidence of different kinetics of expression of inflammatory mediators during primary and secondary infection that likely coincide with innate and adaptive immune response and complement previous observations that emphasize the role of inflammation in the pathogenesis of RSV disease.

Immunoprotective Activity and Safety of a Respiratory Syncytial Virus Vaccine: Mucosal Delivery of Fusion Glycoprotein with a CpG Oligodeoxynucleotide Adjuvant

ABSTRACT CpG oligodeoxynucleotides (ODN) were identified that stimulated immunoglobulin production and cell proliferation in cotton rat cells in vitro. Three of these ODN were used as a mucosal adjuvant in the noses of cotton rats immunized via this route with respiratory syncytial virus fusion (F) protein. The CpG ODN markedly increased the cotton rat humoral neutralizing-antibody response to respiratory syncytial virus. Such immunized animals had a marked reduction in the production of infectious virus after a live-virus challenge. Animals immunized with the combination of F protein and CpG developed enhanced pulmonary pathology consisting of alveolitis and interstitial pneumonitis after a live-virus challenge. Similar enhanced disease has been seen in cotton rats and children immunized with formalin-inactivated respiratory syncytial virus.

Monophosphoryl lipid A adjuvant reverses a principal histologic parameter of formalin-inactivated respiratory syncytial virus vaccine-induced disease.

The mechanisms by which administration of a formalin-inactivated respiratory syncytial virus vaccine resulted in enhanced disease among children after they later became naturally infected with the virus remains largely undefined. After immunization and live virus challenge, the cotton rat demonstrated the histopathologic marker of the enhanced disease, polymorphonuclear leukocyte infiltration of lung alveolar spaces. We now report that immunization with formalin-inactivated vaccine formulated with the adjuvant, 3-deacylated monophosphoryl lipid A, dramatically reduces or eliminates the polymorphonuclear leukocyte infiltration within the alveoli of cotton rats post-challenge. We suggest, that this or similar adjuvants may be beneficial components of candidate non-replicating respiratory syncytial virus vaccines, whose development has been hampered by safety concerns.

Efficacy and Safety Studies of a Recombinant Chimeric Respiratory Syncytial Virus FG Glycoprotein Vaccine in Cotton Rats

ABSTRACT Several formulations of a recombinant chimeric respiratory syncytial virus (RSV) vaccine consisting of the extramembrane domains of the F and G glycoproteins (FG) were tested in cotton rats to evaluate efficacy and safety. The FG vaccine was highly immunogenic, providing nearly complete resistance to pulmonary infection at doses as low as 25 ng in spite of inducing relatively low levels of serum neutralizing antibody at low vaccine doses. Upon RSV challenge animals primed with FG vaccine showed quite mild alveolitis and interstitial pneumonitis, which were eliminated by the addition of monophosphoryl lipid A to the formulation.

Age-Related Differences in Pulmonary Cytokine Response to Respiratory Syncytial Virus Infection: Modulation by Anti-inflammatory and Antiviral Treatment

BACKGROUND Respiratory syncytial virus (RSV) is the major cause of severe lower respiratory tract infection in infants and young children. Recently, RSV has also been recognized as a serious health risk in elderly individuals, but the pathogenesis of RSV infection in elderly individuals remains unknown. METHODS Dynamics of pulmonary cytokine response (including interferon- gamma , interleukin [IL]-4, IL-10, IL-6, monocyte chemoattractant protein-1, and growth-regulated oncogene [GRO] mRNA) during acute RSV infection were investigated in young (<2 months old) and aged (>9 months old) cotton rats (Sigmodon hispidus). Therapeutic treatments that diminish viral replication (antiviral antibody) and pulmonary inflammation (anti-inflammatory corticosteroid) in RSV-infected cotton rats were used to evaluate the contribution of virus replication and inflammation to the development of RSV disease with respect to age. RESULTS The time of the peak expression of the majority of cytokines was shifted with respect to age. Antiviral and anti-inflammatory treatments had a similar effect on cytokine expression in aged and young cotton rats. GRO mRNA transcripts were more abundant in the lungs of aged cotton rats. CONCLUSIONS The present study reports an age-related delay in the pulmonary cytokine response to RSV and an imbalance in chemokine production with respect to age and underscores different components of RSV pathogenesis with respect to their molecular signature.