Influenza C and D Viruses Demonstrated a Differential Respiratory Tissue Tropism in a Comparative Pathogenesis Study in Guinea Pigs.

Influenza C virus (ICV) is increasingly associated with community-acquired pneumonia (CAP) in children and its disease severity is worse than the influenza B virus, but similar to influenza A virus associated CAP. Despite the ubiquitous infection landscape of ICV in humans, little is known about its replication and pathobiology in animals. The goal of this study was to understand the replication kinetics, tissue tropism, and pathogenesis of human ICV (huICV) in comparison to the swine influenza D virus (swIDV) in guinea pigs. Intranasal inoculation of both viruses did not cause clinical signs, however, the infected animals shed virus in nasal washes. The huICV replicated in the nasal turbinates, soft palate, and trachea but not in the lungs while swIDV replicated in all four tissues. A comparative analysis of tropism and pathogenesis of these two related seven-segmented influenza viruses revealed that swIDV-infected animals exhibited broad tissue tropism with an increased rate of shedding on 3, 5, and 7 dpi and high viral loads in the lungs compared to huICV. Seroconversion occurred late in the huICV group at 14 dpi, while swIDV-infected animals seroconverted at 7 dpi. Guinea pigs infected with huICV exhibited mild to moderate inflammatory changes in the epithelium of the soft palate and trachea, along with mucosal damage and multifocal alveolitis in the lungs. In summary, the replication kinetics and pathobiological characteristics of ICV in guinea pigs agree with the clinical manifestation of ICV infection in humans, and hence guinea pigs could be used to study these distantly related influenza viruses. IMPORTANCE Similar to influenza A and B, ICV infections are seen associated with bacterial and viral co-infections which complicates the assessment of its real clinical significance. Further, the antivirals against influenza A and B viruses are ineffective against ICV which mandates the need to study the pathobiological aspects of this virus. Here we demonstrated that the respiratory tract of guinea pigs possesses specific viral receptors for ICV. We also compared the replication kinetics and pathogenesis of huICV and swIDV, as these viruses share 50% sequence identity. The tissue tropism and pathology associated with huICV in guinea pigs are analogous to the mild respiratory disease caused by ICV in humans, thereby demonstrating the suitability of guinea pigs to study ICV. Our comparative analysis revealed that huICV and swIDV replicated differentially in the guinea pigs suggesting that the type-specific genetic differences can result in the disparity of the viral shedding and tissue tropism.

Human Monoclonal Antibody Derived from Transchromosomic Cattle Neutralizes Multiple H1 Clades of Influenza A Virus by Recognizing a Novel Conformational Epitope in the Hemagglutinin Head Domain.

Influenza remains a global health risk and challenge. Currently, neuraminidase (NA) inhibitors are extensively used to treat influenza, but their efficacy is compromised by the emergence of drug-resistant variants. Neutralizing antibodies targeting influenza A virus surface glycoproteins are critical components of influenza therapeutic agents and may provide alternative strategies to the existing countermeasures. However, the major hurdle for the extensive application of antibody therapies lies in the difficulty of generating nonimmunogenic antibodies in large quantities rapidly. Here, we report that one human monoclonal antibody (MAb), 53C10, isolated from transchromosomic (Tc) cattle exhibits potent neutralization and hemagglutination inhibition titers against different clades of H1N1 subtype influenza A viruses. In vitro selection of antibody escape mutants revealed that 53C10 recognizes a novel noncontinuous epitope in the hemagglutinin (HA) head domain involving three amino acid residues, glycine (G), serine (S), and glutamic acid (E) at positions 172, 207, and 212, respectively. The results of our experiments supported a critical role for substitution of arginine at position 207 (S207R) in mediating resistance to 53C10, while substitutions at either G172E or E212A did not alter antibody recognition and neutralization. The E212A mutation may provide structural stability for the epitope, while the substitution G172E probably compensates for loss of fitness introduced by S207R. Our results offer novel insights into the mechanism of action of MAb 53C10 and indicate its potential role in therapeutic treatment of H1 influenza virus infection in humans.IMPORTANCE Respiratory diseases caused by influenza viruses still pose a serious concern to global health, and neutralizing antibodies constitute a promising area of antiviral therapeutics. However, the potential application of antibodies is often hampered by the challenge in generating nonimmunogenic antibodies in large scale. In the present study, transchromosomic (Tc) cattle were used for the generation of nonimmunogenic monoclonal antibodies (MAbs), and characterization of such MAbs revealed one monoclonal antibody, 53C10, exhibiting a potent neutralization activity against H1N1 influenza viruses. Further characterization of the neutralization escape mutant generated using this MAb showed that three amino acid substitutions in the HA head domain contributed to the resistance. These findings emphasize the importance of Tc cattle in the production of nonimmunogenic MAbs and highlight the potential of MAb 53C10 in the therapeutic application against H1 influenza virus infection in humans.

Little heterogeneity among genes encoding heat-labile and heat-stable toxins of enterotoxigenic Escherichia coli strains isolated from diarrheal pigs.

To examine whether the heat-labile enterotoxin gene in porcine enterotoxigenic Escherichia coli (ETEC) strains is as divergent as in human ETEC strains, we sequenced the heat-labile and heat-stable toxin genes from 52 and 33 porcine ETEC strains, respectively. We found that the STa gene is identical, that the LT gene has only two mutations in 4 (of 52) strains, and that both mutations cause a reduction in GM1 binding and toxicity.

Imaging of male infertility: pictorial review.

OBJECTIVE: This article will review the workup of infertility in a male. The imaging of common conditions associated with infertility, including varicocele, ejaculatory duct obstruction, seminal vesicle agenesis, and undescended testis, will be shown, as well as other conditions that can be incidentally seen. CONCLUSION: The analysis of infertility in males has become more common in recent years. The practicing radiologist should be familiar with the evaluation of the infertile man and the common radiologic findings and disease processes associated with infertility.

Antibodies derived from a toxoid MEFA (multiepitope fusion antigen) show neutralizing activities against heat-labile toxin (LT), heat-stable toxins (STa, STb), and Shiga toxin 2e (Stx2e) of porcine enterotoxigenic Escherichia coli (ETEC).

Enterotoxigenic Escherichia coli (ETEC) strains are the main cause of diarrhea in pigs. Pig diarrhea especially post-weaning diarrhea remains one of the most important swine diseases. ETEC bacterial fimbriae including K88, F18, 987P, K99 and F41 promote bacterial attachment to intestinal epithelial cells and facilitate ETEC colonization in pig small intestine. ETEC enterotoxins including heat-labile toxin (LT) and heat-stable toxins type Ia (porcine-type STa) and type II (STb) stimulate fluid hyper-secretion, leading to watery diarrhea. Blocking bacteria colonization and/or neutralizing enterotoxicity of ETEC toxins are considered effective prevention against ETEC diarrhea. In this study, we applied the MEFA (multiepitope fusion antigen) strategy to create toxoid MEFAs that carried antigenic elements of ETEC toxins, and examined for broad antitoxin immunogenicity in a murine model. By embedding STa toxoid STaP12F (NTFYCCELCCNFACAGCY), a STb epitope (KKDLCEHY), and an epitope of Stx2e A subunit (QSYVSSLN) into the A1 peptide of a monomeric LT toxoid (LTR192G), two toxoid MEFAs, 'LTR192G-STb-Stx2e-STaP12F' and 'LTR192G-STb-Stx2e-3xSTaP12F' which carried three copies of STaP12F, were constructed. Mice intraperitoneally immunized with each toxoid MEFA developed IgG antibodies to all four toxins. Induced antibodies showed in vitro neutralizing activities against LT, STa, STb and Stx2e toxins. Moreover, suckling piglets born by a gilt immunized with 'LTR192G-STb-Stx2e-3xSTaP12F' were protected when challenged with ETEC strains, whereas piglets born by a control gilt developed diarrhea. Results from this study showed that the toxoid MEFA induced broadly antitoxin antibodies, and suggested potential application of the toxoid MEFA for developing a broad-spectrum vaccine against ETEC diarrhea in pigs.

How to optimize clinical breast MR imaging practices and techniques on Your 1.5-T system.

Magnetic resonance (MR) imaging, when used in conjunction with mammography and ultrasonography, can be a powerful tool for breast imaging. There are various clinical scenarios in which MR imaging may provide key information that leads to an alteration in treatment plans (eg, by demonstrating features that were occult at physical examination or conventional imaging). Although many benign and malignant entities enhance at contrast material-enhanced breast MR imaging, the morphologic characteristics and kinetic profiles of lesions help narrow the differential diagnosis. To optimize the quality of the morphologic and kinetic information yielded by breast MR imaging, the radiologist must attend to various practical and technical prerequisites: A bilateral breast coil should be used with prone positioning of the patient. An MR imaging system with a high-field-strength magnet is needed, and the magnetic field must be homogeneous across the field of view, which should include both breasts. A T2-weighted sequence should be applied first to identify any cysts and should be followed by three-dimensional imaging with a T1-weighted spoiled gradient-echo sequence after the intravenous administration of a gadolinium chelate. To minimize artifacts, a direction other than the anterior-posterior direction should be selected for phase encoding. To suppress the signal from fat, a frequency-selective pulse should be applied during imaging, or the unenhanced MR imaging data should be subtracted from the contrast-enhanced MR imaging data during postprocessing. The imaging section thickness should be 3 mm or less, the pixel size should be less than 1 mm in each in-plane direction, and the total acquisition time should be less than 2 minutes.

Ultrasound detection of nonpalpable mammographically occult malignancy.

OBJECTIVE: To evaluate the prevalence of occult malignancy with screening breast ultrasound. METHODS: All ultrasound-guided core needle breast biopsies performed between January 1, 1999, and June 30, 2001, were retrospectively reviewed. Lesions were identified during screening breast ultrasound in high-risk women with no mammographic or palpable abnormality in either breast, a unilateral mammographic or palpable abnormality in the contralateral breast, or a unilateral mammographic or palpable abnormality in a different quadrant of the same breast. All ultrasound-detected lesions were histologically verified. RESULTS: Six hundred and fifty-two women with a mean age of 49 years underwent 698 biopsies during the study period. Three hundred and forty-nine of these lesions were detected at screening breast ultrasound. Out of 349, 11 (3.2%) had a mammographically and clinically occult malignancy. Nine cancers were found in women with no mammographic or palpable abnormality. Two cancers were found in the same breast as the mammographic or palpable abnormality. None were found in the breast contralateral to a palpable or mammographic abnormality. CONCLUSION: Screening breast ultrasound of high-risk women has a similar detection rate for occult carcinoma as screening mammography, but has a low positive predictive value in cases where biopsy is performed.

Infantile leukemia presenting with cholestasis secondary to massive pancreatic infiltration.

We present a 10-week-old infant who presented with cholestasis. Biliary obstruction secondary to massive pancreatic infiltration was demonstrated by ultrasound. A diagnosis of acute lymphoid leukemia was confirmed. Enlargement of the pancreas is unusual both in this age group and in leukemia. Infantile leukemia, although rare and usually not associated with gastrointestinal presentations, should be considered as a cause of pancreatic enlargement and neonatal cholestasis.