Use of recombinant envelope proteins for serological diagnosis of Dengue virus infection in an immunochromatographic assay.

An immunochromatographic test that incorporates recombinant antigens (Dengue Duo Rapid Strip Test; PanBio, Brisbane, Australia) has recently become commercially available. This assay is performed in 15 min and detects both immunoglobulin M (IgM) and IgG in a capture format. The four recombinant proteins used represent the N-terminal 80% of the viral envelope glycoproteins of dengue viruses 1, 2, 3, and 4, respectively. The sensitivity and specificity of the recombinant-antigen-based assay were 90 and 86%, respectively. The similar diagnostic performance of these antigens to that of enzyme-linked immunosorbent assays using whole dengue virus suggests that they mimic whole dengue viruses in primary structure and epitope conformation. These results suggest that recombinant proteins can be used in diagnostic assays for dengue to overcome safety issues associated with the use of whole virus.

[Cerebral arterial aneurysm in a child with acquired immunodeficiency syndrome: case report]. / Aneurisma de artéria cerebral em criança com síndrome da imunodeficiência adquirida: relato de caso.

Cerebral aneurysmal arteriopathy of the circle of Willis is an uncommon manifestation of acquired human immunodeficiency virus (HIV) infection and up to now only 15 cases have been published in the literature. For this reason we add our experience of this rare case, and review the most important aspects related to this entity. The patient is a 6 year old male with perinatal transmitted AIDS, tetraparethic, developed symptoms characterized by episodes of dystonic postures. The computed tomography of the brain showed aneurismal arteriopathy of the circle of Willis. He had a previous normal examination. The review of the literature shows the pathological abnormalities of the affected vessels are mainly medial fibrosis, with destruction of the internal elastic lamina and intimal hyperplasia. The etiology for the vasculitis is unknown. Varicela zoster virus, as well as HIV by itself, can be related to the physiopathology of the vasculitis. On conclusion, it can be said that although uncommon, such complications are of great importance by the fact that the patients with vascular aneurismal arteriopathy are in high risk for vascular accidents, and once a diagnosis was made, death occurs in less than 6 months, according to the literature.

Quantitative immunocapture PCR assay for detection of Campylobacter jejuni in foods.

The rapid detection of food-borne bacterial pathogens as part of a quality control program is necessary for the maintenance of a safe food supply. In this report, we present our findings for an immunocapture PCR method for the detection of Campylobacter jejuni in foods. The method permits direct detection of the pathogen without an enrichment step and can be performed in approximately 8 h. Assay results are quantitative, and one cell in a milliliter sample can be detected. Application of the method to spiked milk samples and chicken skin washes did not affect the sensitivity of the assay.

Ultrastructural analysis of attachment to and penetration of capillaries in the murine pons, midbrain, thalamus, and hypothalamus by Nocardia asteroides.

The attachment to and penetration of endothelial cells in the pons and midbrain (especially the substantia nigra) regions of the brains of BALB/c mice by log-phase Nocardia asteroides GUH-2 cells were determined by both scanning and transmission electron microscopic analysis. Within 15 min after exposure, the nocardiae attached to the surface of the endothelial cell membrane. This attachment occurred primarily at the growing tip of the nocardial filament, and the outermost layer of the nocardial cell wall had regions (electron-dense areas) that bound firmly to the cytoplasmic membrane of the host cell. There appeared to be specificity for this binding localized within the capillaries and arterioles because some regions had large numbers of bacteria bound, whereas adjacent areas had no bacterial cells. Nocardial filaments that attached by the apex induced a cuplike deformation of the endothelial cell membrane. This was followed by a rapid penetration of the endothelial cell so that within 25 min many of the bacteria were internalized within the host cell. These internalized bacteria remained within vesicles, and there was no ultrastructural evidence of damage to the nocardial cell during this process. Heat-killed GUH-2 cells still attached to endothelial surfaces (at a reduced frequency), but they did not penetrate into the endothelial cell. These data suggest that brain-invasive nocardiae possess both an adhesin for attachment to the membrane of endothelial cells and an invasion factor that promotes nocardial penetration of these cells.

Site-specific growth of Nocardia asteroides in the murine brain.

The growth of Nocardia asteroides GUH-2 and two mutants (NG-49 and I-38-syn) in regions of the brains of BALB/c mice was determined by microdissection and viable counting. GUH-2 grew throughout the murine brain but at different growth rates that depended on the specific location. The rate of increase in total CFU per brain during GUH-2 infection was unaffected by the inoculum size; however, in five of eight brain regions, an alteration in the inoculum size resulted in altered nocardial growth rates. Mutant NG-49 showed a significantly slower rate of increase in total CFU per brain than did the parental strain, GUH-2, and significantly decreased growth rates in seven brain regions. Mutant I-38-syn showed a rate of increase in total CFU per brain similar to that of the parental strain; however, this mutant grew significantly faster in the cerebellum and pons-medulla. Growth appeared to be a necessary precursor to the cellular damage that resulted in the variety of neurological disorders observed in mice infected with N. asteroides GUH-2, because mutant NG-49 exhibited a decreased ability to grow in specific regions of the brain and did not induce signs of neurological damage. In contrast, mutant I-38-syn induced neurological signs in a larger percentage of the infected animals than did parental strain GUH-2 and grew better in certain regions of the brain than did the parental strain. Furthermore, there appeared to be a relationship between the growth of N. asteroides in the substantia nigra and the induction of an L-dopa-responsive head shake that was observed in some of the mice following a sublethal intravenous injection of N. asteroides GUH-2.

Adherence of Nocardia asteroides within the murine brain.

Nonlethal infection of BALB/c mice with Nocardia asteroides GUH-2 (GUH-2) produces a variety of neurological signs, including an L-dopa-responsive movement disorder in 10 to 15% of the infected population. To study nocardial interactions with the brain, we characterized the attachment of GUH-2 within specific regions through the use of microdissection. Following an intravenous injection of a single-cell suspension of log-phase GUH-2, viable cells were recovered from all regions of the brain, and the distribution of the nocardiae was independent of the size of the inoculum. In addition, two mutants of GUH-2 were found to possess significantly altered binding characteristics with regard to both the percentage of the inoculum bound per brain and the relative distribution of adherence to regions of the brain, when compared with the parental strain. These results indicated that GUH-2 bound throughout the murine brain and suggested that GUH-2 utilized specific receptors to facilitate this attachment.