Bifunctional CD4-DC-SIGN fusion proteins demonstrate enhanced avidity to gp120 and inhibit HIV-1 infection and dissemination.

Early stages of mucosal infection are potential targets for HIV-1 prevention. CD4 is the primary receptor in HIV-1 infection whereas DC-SIGN likely plays an important role in HIV-1 dissemination, particularly during sexual transmission. To test the hypothesis that an inhibitor simultaneously targeting both CD4 and DC-SIGN binding sites on gp120 may provide a potent anti-HIV strategy, we designed constructs by fusing the extracellular CD4 and DC-SIGN domains together with varied arrangements of the lengths of CD4, DC-SIGN and the linker. We expressed, purified and characterized a series of soluble CD4-linker–DC-SIGN (CLD) fusion proteins. Several CLDs, composed of a longer linker and an extra neck domain of DC-SIGN, had enhanced affinity for gp120 as evidenced by molecular-interaction analysis. Furthermore, such CLDs exhibited significantly enhanced neutralization activity against both laboratory-adapted and primary HIV-1 isolates. Moreover, CLDs efficiently inhibited HIV-1 infection in trans via a DC-SIGN-expressing cell line and primary human dendritic cells. This was further strengthened by the results from the human cervical explant model, showing that CLDs potently prevented both localized and disseminated infections. This is the first time that soluble DC-SIGN-based bifunctional proteins have demonstrated anti-HIV potency. Our study provides proof of the concept that targeting both CD4 and DC-SIGN binding sites on gp120 represents a novel antiviral strategy. Given that DC-SIGN binding to gp120 increases exposure of the CD4 binding site and that the soluble forms of CD4 and DC-SIGN occur in vivo, further improvement of CLDs may render them potentially useful in prophylaxis or therapeutics

Tetralogy of Fallot

Tetralogy of Fallot is a congenital cardiac malformation that consists of an interventricular communication, also known as a ventricular septal defect, obstruction of the right ventricular outflow tract, override of the ventricular septum by the aortic root, and right ventricular hypertrophy

The HIV-1 transmission bottleneck

It is well established that most new systemic infections of HIV-1 can be traced back to one or a limited number of founder viruses. Usually, these founders are more closely related to minor HIV-1 populations in the blood of the presumed donor than to more abundant lineages. This has led to the widely accepted idea that transmission selects for viral characteristics that facilitate crossing the mucosal barrier of the recipient’s genital tract, although the specific selective forces or advantages are not completely defined. However, there are other steps along the way to becoming a founder virus at which selection may occur. These steps include the transition from the donor’s general circulation to the genital tract compartment, survival within the transmission fluid, and establishment of a nascent stable local infection in the recipient’s genital tract. Finally, there is the possibility that important narrowing events may also occur during establishment of systemic infection. This is suggested by the surprising observation that the number of founder viruses detected after transmission in intravenous drug users is also limited. Although some of these steps may be heavily selective, others may result mostly in a stochastic narrowing of the available founder pool. Collectively, they shape the initial infection in each recipient

Transcatheter closure of persistent ductus arteriosus in infants using the Amplatzer duct occluder

AIM—To evaluate whether transcatheter closure with the Amplatzer duct occluder offers an alternative to surgical treatment in infants with a persistent ductus arteriosus.
METHODS—12 patients under 1 year of age (age 1-11 months, body weight 2.6-8.7 kg) with clinical and echocardiographic findings of a significant duct were considered for transcatheter closure with the Amplatzer occluder. The device is made of a Nitinol and polyester fabric mesh and provides occlusion by stenting the duct. Measured angiographically, the narrowest diameter of the ducts ranged from 1.5-5 mm; in six patients pulmonary hypertension was also present.
RESULTS—The devices were implanted and complete duct occlusion was demonstrated during follow up in 10 patients. Procedure related difficulties occurred in nine of the 12 cases and led to relatively long procedure and fluoroscopy times (procedure time 50-180 minutes, median 80 minutes; fluoroscopy time 4.9-49 minutes, median 16( )minutes). In two infants transcatheter closure could not be achieved and surgical duct ligation had to be carried out.
CONCLUSIONS—In small infants with a persistent ductus arteriosus the Amplatzer duct occluder offers an alternative to surgical treatment, but further improvement of the implantation system is necessary before the procedure can be recommended as the treatment of choice.


Keywords: persistent ductus arteriosus; transcatheter closure; infants; Amplatzer duct occlude

Differential Binding of IgG and IgA to Mucus of the Female Reproductive Tract

<div><p>Cells of the endocervix are responsible for the secretion of mucins, which provide an additional layer of protection to the female reproductive tract (FRT). This barrier is likely fortified with IgA as has previously been shown in the gastrointestinal tract and lungs of mice. Mucus associated IgA can facilitate clearance of bacteria. While a similar function for IgG has been proposed, an association with mucus has not yet been demonstrated. Here we find that IgA and IgG are differentially associated with the different types of mucus of the FRT. We observed that while both IgA and IgG are stably associated with cervical mucus, only IgG is associated with cervicovaginal mucus. These findings reveal that antibodies can bind tightly to mucus, where they can play a significant role in the fortification of the mucus barriers of the FRT. It may be possible to harness this interaction in the development of vaccines designed to protect the FRT mucosal barriers from sexually transmitted diseases such as HIV.</p></div

Detection of immunogloblulins in endocervical explants.

<p>Sectioned explants of endocervix were stained with antibodies to detect IgA (green) and IgG (red). Cytokeratin 7 (blue) was also stained to identify the layer of columnar cells. Each row represents a different donor sample. Images were acquired with a 100X lens as a panel and then stitched together. Second and third columns have red or green color removed, respectively, from image in first column.</p

Immunofluorescence of mucins in CM and CVM.

<p>CM (A) and CVM (B) were frozen, cryosetioned, and fixed for immunofluorescent staining. All sections were stained for WGA (blue), mucin5AC (green), and mucin5B (red). Upper panels are images acquired with a 20X (A) or 10X (B) lens. Lower panels were acquired with a 100X lens.</p