Validation of the National Institute of Neurological Disorders and Stroke Spinal Cord Injury MRI Common Data Elements Instrument.

BACKGROUND AND PURPOSE: The National Institute of Neurological Disorders and Stroke common data elements initiative was created to provide a consistent method for recording and reporting observations related to neurologic diseases in clinical trials. The purpose of this study is to validate the subset of common data elements related to MR imaging evaluation of acute spinal cord injury. MATERIALS AND METHODS: Thirty-five cervical and thoracic MR imaging studies of patients with acute spinal cord injury were evaluated independently in 2 rounds by 5 expert reviewers. Intra- and interrater agreement were calculated for 17 distinct MR imaging observations related to spinal cord injury. These included ordinal, categoric, and continuous measures related to the length and location of spinal cord hemorrhage and edema as well as spinal canal and cord measurements. Level of agreement was calculated using the interclass correlation coefficient and kappa. RESULTS: The ordinal common data elements spinal cord injury elements for lesion center and rostral or caudal extent of edema or hemorrhage demonstrated agreement ranging from interclass correlation coefficient 0.68 to 0.99. Reproducibility ranged from 0.95 to 1.00. Moderate agreement was observed for absolute length of hemorrhage and edema (0.54 to 0.60) with good reproducibility (0.78 to 0.83). Agreement for the Brain and Spinal Injury Center score showed the lowest interrater agreement with an overall kappa of 0.27 (0.20, 0.34). For 7 of the 8 variables related to spinal cord injury, agreement improved between the first and second evaluation. Continuous diameter measures of the spinal cord and spinal canal using interclass correlation coefficient varied substantially (0.23 to 0.83). CONCLUSIONS: Agreement was more consistent for the ordinal measures of spinal cord injury than continuous measures. Good to excellent agreement on length and location of spinal cord hemorrhage and edema can be achieved with ordinal measures alone.

Reduced FOV diffusion tensor MR imaging and fiber tractography of pediatric cervical spinal cord injury.

STUDY DESIGN: Quantitative study. OBJECTIVES: To evaluate the effectiveness of pediatric spinal cord diffusion tensor tractography (DTT) generated from reduced field of view diffusion tensor imaging (DTI) data and investigate whether there are differences in these values between typically developing (TD) subjects and patients with spinal cord injury (SCI). SETTING: Temple University Hospital and Shriners Hospitals for Children-Philadelphia, USA. METHODS: A total of 20 pediatric subjects including 10 healthy subjects (age 15.13±3.51 years (mean±s.d.) and age range 11-21 years) and 10 subjects with SCI in the cervical area (age 13.8±3.26 years and age range 8-20 years) were recruited, and scanned using a 3.0T MR scanner. Quantitative parameters of DTI and fiber tracking, such as mean fractional anisotropy (FA), apparent diffusion coefficient (ADC), mean length of fiber tracts and tract density, were calculated for each subject. RESULTS: Subjects with SCI showed reduced FA and tract density, and increased ADC values and length of fiber tracts, compared with controls. Statistically significant differences were seen in FA (P=0.0238) and tract density (P=0.0005) between controls and subjects with SCI, whereas there were no significant differences in ADC values and length of fiber tracts. The tractography visually showed that the white matter tracts (blue color) of the SCI patients were overall less abundant and less organized compared with control cases. CONCLUSION: The results show that DTI and DTT could be used as surrogate markers for quantification and visualization of the injured spinal cord.

Diffusion Tensor Imaging of the Normal Cervical and Thoracic Pediatric Spinal Cord.

BACKGROUND AND PURPOSE: DTI data of the normal healthy spinal cord in children are limited compared with adults and are typically focused on the cervical spinal cord. The purpose of this study was the following: to investigate the feasibility of obtaining repeatable DTI parameters along the entire cervical and thoracic spinal cord as a function of age in typically developing pediatric subjects; to analyze the DTI parameters among different transverse levels of the cervical and thoracic spinal cord; and to examine the sex differences in DTI parameters along the cervical and thoracic spinal cord. MATERIALS AND METHODS: Twenty-two subjects underwent 2 identical scans by using a 3T MR imaging scanner. Axial diffusion tensor images were acquired by using 2 overlapping slabs to cover the cervical and thoracic spinal cord. After postprocessing, DTI parameters were calculated by using ROIs drawn on the whole cord along the entire spinal cord for both scans. RESULTS: An increase in fractional anisotropy and a decrease in mean diffusivity, axial diffusivity, and radial diffusivity were observed with age along the entire spinal cord. Significantly lower fractional anisotropy and higher mean diffusivity values were observed in the lower cervical cord compared with the upper cervical cord. Axial diffusivity values in the cervical cord were higher compared with the thoracic cord. No statistically significant sex differences were observed for all DTI parameters. There was a moderate-to-strong repeatability for all DTI parameters. CONCLUSIONS: This study provides an initial understanding of DTI values of the spinal cord relevant to age and sex and shows that obtaining repeatable DTI values of the entire cord in children is feasible.

Isolation and identification of AIDA-I receptors in porcine intestinal mucus.

Porcine AIDA-I positive Escherichia coli causes diarrhea in neonatal piglets and AIDA-I adhesin is an important virulence factor involved in intestinal colonization with biofilm formation. This biofilm consists of AIDA-I(+)E. coli bacteria stratified within mucus layers covering the intestinal mucosa. Based on the intimate interaction between AIDA-I(+)E. coli and mucus within the intestinal biofilm, we hypothesized that porcine intestinal mucus contains receptor(s) for AIDA-I adhesin. Since porcine AIDA-I receptors have not been identified, we employed affinity chromatography and in vitro adhesion assays to investigate AIDA-I binding proteins in porcine intestinal mucus that might serve as receptors for attachment of AIDA-I positive E. coli. We demonstrated that porcine mucus contains 65 and 120kDa proteins (p65 and p120) that bind with high affinity to purified AIDA-I adhesin and that AIDA-I positive E. coli binds to these proteins with higher affinity than do AIDA-I negative mutant. The identity of p65 was not determined based on LC-MS/MS data, whereas p120 was matched to two nuclear proteins (namely, DNA damage binding protein and splicing factor 3b) and one cytoplasmic protein, which is an IgG Fc binding protein. Based on similar amino acid homology, molecular weight, structural similarity to mucin and reported evidence of being secreted by goblet cells into the intestinal lumen, we think that the IgG Fc binding protein is most likely candidate to serve as a potential receptor in intestinal mucus for AIDA-I adhesin.

Characterization and immuno-detection of AIDA-I adhesin isolated from porcine Escherichia coli.

A relatively high percentage of porcine Escherichia coli isolates from cases associated with neonatal and post-weaning diarrhea are positive for the gene encoding adhesin involved in diffuse adhesion I (AIDA-I). This gene and its corresponding protein were first identified and characterized in E. coli strain 2787 isolated from human infantile diarrhea. Little is known about the properties of the AIDA-I protein and its immuno-detection on surface of AIDA-I positive porcine E. coli isolates. In this study, we demonstrated that the AIDA-I adhesin isolated from porcine AIDA-I positive E. coli is an acidic protein consisting of five isoforms. It has a similar molecular weight (100 kDa) and relatively high amino acid homology (78-87%) with the AIDA-I adhesin expressed by human AIDA-I positive E. coli strain 2787. Based on limited comparison, it appears that there is a very high homology among AIDA-I proteins expressed by porcine AIDA-I positive E. coli isolates. Sensitivity of detection of surface AIDA-I adhesin of PCR-positive AIDA-I E. coli by immuno-dot-blot and coagglutination tests was 76 and 71%, respectively, whereas specificity was 89 and 84%, respectively. These tests are unlikely to be used for diagnostic detection of AIDA-I positive E. coli due to the relatively low sensitivity; however, they may be potentially useful for identification of false positive reactions generated by other diagnostic tests.

Changes in the leucocyte subpopulations of the palatine tonsillar crypt epithelium of pigs in response to Streptococcus suis type 2 infection.

The tonsils are portal of entry and a site of multiplication and persistence for a variety of pathogens, including Streptococcus suis (S. suis), which is a common cause of meningitis, septicemia and arthritis in pigs. Understanding the early changes that occur in the first barrier of the tonsil, i.e. the crypt epithelium, in response to S. suis infection is critical in clarifying the pathogenesis of this disease and for the future development of efficient methods of mucosal vaccination. In this study, we investigated the early changes, from 18 to 72 h, that occur in leucocyte subpopulations of the crypt epithelium of the palatine tonsils of 3-week-old pigs in response to S. suis type 2 infection. Monoclonal antibodies against leucocyte markers CD3, CD4, CD8, gammadelta T cell receptor, lambda-immunoglobulin light-chain, myeloid cells, and major histocompatibility complex class II molecule (MHC-II) were used in an avidin-biotin immunoperoxidase technique. An increase in the number of lambda-immunoglobulin light-chain positive cells (B cell subset) was noticed in crypts of S. suis-infected animals from 18 h after infection onwards. This increase was significant at 18 and 48 h after infection. The number of CD4 and CD8 cells was greater from 18 h onwards, with a significant increase at 24 and 72 h post-infection. No significant difference in numbers of CD3, gammadelta T cell receptor and MHC-II positive cells was detected in the crypts of infected animals compared to controls. Macrophages, neutrophils and crypt epithelial cells stained positively with the myeloid marker, and the area of crypt epithelium positive for this marker was increased in the crypts of infected animals, with a significant difference detected at 24 and 72 h after infection. These results suggest that there is participation of the innate immunity in the early phase of S. suis infection, represented by neutrophils, macrophages and likely epithelial cells, and that there is a potential for the initiation of both humoral and cellular responses against S. suis within the crypt epithelium of the palatine tonsil.

Necrotic enteritis: effect of barley, wheat and corn diets on proliferation of Clostridium perfringens type A.

Necrotic enteritis, caused by Clostridium perfringens type A, is more prevalent in broilers fed wheat or barley diets than in those fed a corn diet. We compared the effects of wheat, barley and corn diets on in vitro proliferation of C. perfringens type A. Bacteria were inoculated into the supernatants delivered from either digested or non-digested barley, wheat and corn diets mixed with thioglycollate medium (1:3). Colony forming units were counted following incubation for 6 h at 40 degrees C. There were no significant differences in clostridial proliferation among non-digested diets. Bacterial proliferation in the digested wheat and barley diets was significantly higher than in the digested corn diet. These findings suggest that the increased incidence of necrotic enteritis in broilers fed barley and wheat diets compared with those fed a corn diet may be due in part to increased clostridial proliferation associated with the wheat and barley diets, or to decreased proliferation associated with the corn diet.

Effects of intradermally administered plasmid deoxyribonucleic acid on ovine popliteal lymph node morphology.

In the last decade it has become apparent that bacterial deoxyribonucleic acid (DNA) is recognized as a "danger signal" by the mammalian immune system. To investigate this interaction, sheep were injected intradermally two centimeters distal to the lateral prominence of the fibular head with 400 microg of purified plasmid DNA. Over a 28-day period ultrasound measurements indicated a progressive increase in size of both plasmid and saline (controls) treated popliteal lymph nodes and at Day 30 macroscopic and histological measurements of the lymph nodes were determined. Compared with the contralateral control lymph nodes, plasmid exposed lymph nodes were heavier (2.8 +/- 0.1g vs. 2.0 +/- 0.6 g) and displayed prominent histological changes in the cortex and medulla. Average medullary cord thickness (114.2 +/- 25.2 microm) and the average distance across medullary sinuses (64.4 +/- 2.5 microm) were significantly greater after plasmid exposure relative to contralateral controls (62.7 +/- 14.9 microm and 36.5 +/- 1.0 microm, respectively). Total number of germinal centers (71.4 +/- 17.7) and the total area of germinal centers (4.0 +/- 1.3 mm(2)) within the cortex of popliteal lymph nodes exposed to plasmid were also significantly greater than the controls (40.4 +/- 11.4 and 1.6 +/- 0.5 mm(2), respectively). Our results demonstrate that a single exposure to plasmid DNA has long term effects on regional lymph node weight and morphology.

Plasmid DNA induces increased lymphocyte trafficking: a specific role for CpG motifs.

Bacterial DNA, primarily through immunostimulatory cytosine-guanine (CpG) motifs, induces the secretion of cytokines and activates a variety of effector cells. We investigated the possibility that CpG motifs might also modulate immunosurveillance by altering cell trafficking through a regional lymph node. Intradermal injection of plasmid DNA induced rapid and prolonged increases in the number of lymphocytes collected in efferent lymph. This effect on cell trafficking was not dependent on the expression of an encoded reporter gene but varied with plasmid construct and required a circular form. Injection of synthetic oligodeoxyribonucleotides containing CpG motifs did not alter lymphocyte trafficking but CpG-enhanced plasmid induced a dose-dependent increase in cell trafficking. Phenotypic analyses revealed that the increase in cell trafficking involved all lymphocyte subpopulations and represented a mass movement of cells. These observations reveal that bacterial DNA, through immunostimulatory CpG motifs, alters immunosurveillance by increasing cell recruitment to a regional lymph node.

The importance of interleukin-8 as a neutrophil chemoattractant in the lungs of cattle with pneumonic pasteurellosis.

Interleukin-8 (IL-8), an in vitro and in vivo neutrophil chemoattractant, is expressed at high levels in the lesions observed in bovine pneumonic pasteurellosis. Because of the role of neutrophils in the pathogenesis of pneumonic pasteurellosis, we investigated the relative importance of IL-8 as a neutrophil chemoattractant in this disease. Bronchoalveolar lavage (BAL) fluid was harvested from calves experimentally infected with bovine herpesvirus-1 and challenged with Mannheimia haemolytica. Neutrophil chemotactic activity was measured in pneumonic BAL fluid samples treated with a neutralizing monoclonal antibody to ovine IL-8, and compared to the activity in samples treated with an isotype-matched control antibody. Bronchoalveolar lavage fluid was analyzed at a dilution which induced a half-maximal response, and the concentrations of antibody were optimized in a preliminary experiment. Following incubation of replicate samples of diluted pneumonic bovine BAL fluid with 70 microg/mL of IL-8-neutralizing antibody or control antibody, the neutrophil chemotactic activities of the samples were determined using an in vitro microchemotaxis assay. Overall, pretreatment of BAL fluid samples with neutralizing anti-IL-8 antibody reduced neutrophil chemotactic activity by 15% to 60%, compared to pretreatment with control antibody. This effect was highly significant (P < 0.001), and was present in 5 of 5 samples. These data indicate that IL-8 is an important neutrophil chemoattractant in calves with pneumonic pasteurellosis, but that mediators with actions redundant to those of IL-8 must also be present in the lesions.

Lymphocyte subsets in porcine tonsillar crypt epithelium.

The palatine tonsils are part of the mucosa-associated lymphoid tissue (MALT), strategically located in the oropharynx at the entrance of respiratory and gastrointestinal tracts, and are recognized portals of entry and sites of multiplication and persistence of several pathogens in pigs. As the tonsillar crypt epithelium is in close contact with external environment and the underlying lymphoid tissue, the characterization of the intra-epithelial lymphocyte subpopulations is essential for the understanding of initial steps of pathogenesis of several diseases. In this work we investigated specific lymphocyte subsets in the tonsillar crypt epithelium of 10 adult healthy pigs, using monoclonal antibodies against lymphocyte markers CD3, CD4, CD8, gammadelta T cell receptor and immunoglobulin light-chain in an avidin-biotin immunoperoxidase technique. The crypt epithelium was usually extensively infiltrated by a diverse population of T cells and by B cells. The degree of infiltration of each subset was variable among animals and within individual animals. In the T cell population CD4 cells and gammadelta TCR cells predominated over CD8 cells. These data suggest that the crypt lymphoepithelium is capable of participating in both cellular and humoral immune responses and that gammadelta T cells may play an important role in the defense of this mucosa.

Transtracheal administration of interleukin-12 induces neutrophil responses in the murine lung.

Although the roles of interleukin-12 (IL-12) in the immunomodulation of antigen-specific responses are well characterized, the effects of IL-12 on the respiratory tract following mucosal administration are not well defined. Therefore, we investigated changes in the murine lung shortly after intranasal (i.n.) administration of murine IL-12. We showed that IL-12 induced neutrophil influx to the murine lung in both C57BL/6 and BALB/c mice. Histologic examination revealed that intranasal administration of IL-12 with liposomes induced focal neutrophil infiltration into the alveoli and a significant increase in neutrophils in bronchoalveolar lavage fluids when compared with administration of liposomes alone. In vitro chemotaxis assays indicated that the observed pulmonary neutrophil response induced by IL-12 could have been due in part to the direct chemotactic activity of IL-12 for murine neutrophils.

Production and functional characterization of recombinant bovine interleukin-8 as a specific neutrophil activator and chemoattractant.

Interleukin-8, a member of the chemokine family of cytokines, is a potent neutrophil chemoattractant in many non-rodent species. In this study, recombinant bovine interleukin-8 (rbIL-8) was expressed in bacteria as a glutathione-S-transferase fusion protein. The fusion protein was purified by glutathione-Sepharose affinity chromatography and recombinant rbIL-8 was eluted by cleaving with thrombin. The purified rbIL-8 molecule was approximately 8 kDa and was confirmed as authentic IL-8 by Western analysis. Recombinant bovine IL-8 induced specific dose-dependent in vitro chemotaxis of neutrophils at doses as low as 1.0 ng/ml, and this activity was inhibited by pre-treatment of rbIL-8 with a monoclonal antibody to ovine IL-8. Neutrophils exposed to rbIL-8 developed pseudopodia and became elongated as determined by microscopic analysis and flow cytometry. Injection of 3.3 ng to 3.3 microg of rbIL-8 into the skin of a normal calf induced dose-dependent recruitment of neutrophils but not eosinophils. Intravascular margination of neutrophils was obvious at the injection sites from 15 to 60 min after administration of rbIL-8, and extravascular neutrophil numbers increased steadily from 1 to 18 h after injection. Neutrophils with morphologic features of apoptosis were detected in these lesions at 18 and 30 h after injection, and this correlated with reduction in the number of dermal neutrophils. These results confirm unequivocally that bovine IL-8 functions as a neutrophil, but not an eosinophil, chemoattractant in vitro and in vivo.

Expression of the neutrophil chemoattractant interleukin-8 in the lesions of bovine pneumonic pasteurellosis.

We investigated the expression of interleukin-8 (IL-8) in pneumonic pasteurellosis of cattle because neutrophils are important mediators of tissue injury in this disease and because IL-8 is a major neutrophil chemoattractant in other species. We also compared IL-8 expression in bacterial and viral pneumonia, since the latter lacks the severe neutrophil exudation typical of pneumonic pasteurellosis. IL-8 expression was assessed by northern analysis, in situ hybridization, enzyme-linked immunosorbent assay, and in vivo bioassay. IL-8 mRNA expression was elevated dramatically in lesions of pneumonic pasteurellosis compared to unaffected lung from the same calves. In situ hybridization revealed intense expression of IL-8 mRNA in alveolar macrophages and neutrophils and milder expression in bronchiolar and alveolar epithelium, interstitial cells, and pleural mesothelium. Bronchoalveolar lavage fluid from lesional lung contained 16.06+/-4.00 ng/ml IL-8, whereas those from nonlesional and normal lung contained 0.34+/-0.11 and 0.01+/-0.002 ng/ml, respectively. We detected IL-8 expression at only minimal levels in bovine respiratory syncytial viral pneumonia. Lung extracts from lesions of pneumonic pasteurellosis induced vigorous neutrophil infiltration following injection into bovine skin, and 89% depletion of IL-8 from the extract reduced this neutrophil influx by 60%. These results demonstrate consistent upregulation of IL-8 expression in lesions of pneumonic pasteurellosis, implying a role for IL-8 in the ongoing recruitment of neutrophils to established lesions of pneumonic pasteurellosis. Because neutrophil-mediated tissue injury is critical to the pathogenesis of pneumonic pasteurellosis, these data suggest that neutralization of IL-8 activity could ameliorate the severe clinical signs and lesions of this disease.

Mucosal immunization with recombinant adenoviruses: induction of immunity and protection of cotton rats against respiratory bovine herpesvirus type 1 infection.

To facilitate the evaluation of vaccines against bovine herpesvirus type 1 (BHV-1), a cotton rat model of intranasal (i.n.) BHV-1 infection was established. Cotton rat lung cells were similar to bovine cells in their ability to support BHV-1 replication in vitro. Furthermore, i.n. inoculation of cotton rats with BHV-1 resulted in pulmonary lesions comparable to BHV-1 infection in cattle. Using this model, the potential of i.n. and gastrointestinal (g.i.) immunization was examined with recombinant human adenoviruses expressing glycoprotein D (gD) of BHV-1 to induce protective immunity against BHV-1. The replication-competent virus (gD-dE3) was more efficient than the replication-defective virus (gD-dE1E3) in inducing gD-specific antibody in the serum and in the respiratory tract. Furthermore, i.n. immunization with gD-dE3 stimulated antigen-specific antibody-secreting cells in the lung 12 weeks following immunization. Protection against BHV-1 challenge correlated with gD-specific antibody levels such that i.n. immunization with gD-dE3 conferred complete protection, while g.i. immunization conferred only partial protection of the lungs of most animals against BHV-1 challenge. In comparison, immunization with gD-dE1E3 by either route resulted in only a partial reduction of BHV-1 titre in the respiratory tract. The results obtained demonstrate that mucosal immunization with replication-competent recombinant adenovirus expressing gD of BHV-1 can induce immunity and protection against BHV-1 challenge.

Effect of glutamine or glycine containing oral electrolyte solutions on mucosal morphology, clinical and biochemical findings, in calves with viral induced diarrhea.

Twenty-one diarrheic calves were randomly assigned to 1 of 3 oral electrolyte treatments. The treatments were either a conventional oral electrolyte containing glycine (40 mmol/L) as the amino acid, an oral electrolyte in which glutamine (40 mmol/L) replaced glycine or an electrolyte in which high concentrations of glutamine (400 mmol/L) replaced glycine. The calves were monitored while on trial and at the end of the treatment they were euthanized and a necropsy was immediately performed. Calves fed the high glutamine electrolyte had more treatment failures (2/7 versus 0/7 for each of the other 2 treatments). There was a significant effect of type of electrolyte on fecal consistency. Calves fed the glycine containing electrolyte had the most solid feces. Duodenal villus height was significantly affected by the type of electrolyte: values (mean +/- 1 SEM) were 0.61 +/- 0.09, 0.46 +/- 0.05, and 0.59 +/- 0.07 mm for high glutamine, low glutamine and glycine electrolytes respectively. There was no significant difference in small intestinal surface area between groups. High glutamine treated calves had the greatest capacity to absorb xylose from the small intestine but this difference was not statistically significant. Overall, this trial does not suggest that substituting glutamine for glycine in oral electrolyte solutions improves treatment of diarrheic calves or speeds mucosal healing.

Pathology and immunogenicity in the cotton rat (Sigmodon hispidus) model after infection with a bovine adenovirus type 3 recombinant virus expressing the firefly luciferase gene.

The histopathology of adenovirus pneumonia in cotton rats (Sigmodon hispidus) due to bovine adenovirus type 3-luciferase recombinant virus (BAd3-Luc), which has a 0.7 kb deletion from the early region 3 (E3) replaced with the firefly luciferase gene, was compared with that produced by the parental wild-type (wt) bovine adenovirus type 3 (BAd3). After intranasal inoculation of cotton rats with 3 x 10(7) p.f.u. of BAd3-Luc, the infectious virus titres in the lungs at various times post-infection were similar to those of animals infected with the parental virus. Quantitative analysis of histopathological changes and immunohistochemical staining showed that the character and severity of the lesions were indistinguishable in the two infections. Luciferase activity was detected in the lungs of BAd3-Luc-inoculated animals until 4 days post-infection (p.i.). Antibodies to both BAd3 and luciferase were detected in sera collected from BAd3-Luc-infected animals until at least 6 weeks p.i. These results show that Bad3-Luc produces pulmonary lesions in cotton rats similar to those of wt BAd3 and suggest that BAd3-based vectors may be suitable for the development of live recombinant virus vaccines.

Pathogenesis and immunogenicity of bovine adenovirus type 3 in cotton rats (Sigmodon hispidus).

Intranasal inoculation of cotton rats (Sigmodon hispidus) with 10(8) PFU of bovine adenovirus type 3 (BAd3) resulted in limited virus replication in the lung and trachea. Histopathological changes in the lungs were characterized by necrosis and hyperplasia of bronchiolar epithelium, eosinophilic intranuclear inclusions, pneumocyte type II hyperplasia in the alveoli, and mild peribronchiolar and perivascular lymphocytic infiltration. Immunohistochemically, viral antigens were observed more frequently in bronchiolar epithelial cells than in alveolar cells in cotton rat lung sections stained using a rabbit anti-BAd3 serum. Bronchiolar epithelial changes, intranuclear inclusion bodies, type II pneumocyte proliferation, peribronchiolar infiltration, and immunohistological staining were maximum at Day 3 or Day 4 postinoculation, whereas perivascular infiltration was first observed at Day 8 postinoculation. In addition to the histological study of the pathogenesis of BAd3 infection, we monitored the BAd3-specific immune response in cotton rats. Anti-BAd3 IgG and virus neutralizing antibodies were detected in sera, whereas anti-BAd3 IgA antibodies were found in the sera, lung, and nasal washes. Our results suggest that the cotton rat can serve as a useful small-animal model for investigating the pathogenesis of BAd3 infection, as well as immune responses to BAd3 recombinant virus vaccines.