Egg formation and the early embryonic development of Aspidogaster limacoides Diesing, 1835 (Aspidogastrea: Aspidogastridae), with comments on their phylogenetic significance

Ultrastructural aspects of the early embryonic development of the aspidogastrean Aspidogaster limacoides are described and their phylogenetic implications discussed. Whereas the proximal regions of the uterine lumen usually contain unembryonated eggs or eggs with early embryos, the posterior or distal regions of the uterus are filled with eggs containing a fully-developed cotylocidium. The eggs of A. limacoides can be classified as polylecithal due to the presence of numerous vitellocytes which accompany each fertilized oocyte or ovum during egg formation. The results of the study are described in details under six headings: (1) general characteristics of the intrauterine eggs; (2) eggshell and operculum formation; (3) unembryonated eggs; (4) zygote formation and early cleavage divisions; (5) embryonic envelope formation; and (6) early degeneration or apoptosis of some blastomeres. The late differentiation of the operculum, possible functions of GER-bodies, and the early degeneration of vitellocytes and some blastomeres in this species are compared, drawn and discussed with corresponding observations reported for other parasitic Platyhelminthes. The most important differences are apparent in the number of egg envelopes and their mode of formation in A. limacoides compared with previous reports for both digeneans and cestodes. The results of the present TEM study indicate that the three macromeres, resulting from two cleavage divisions, take part in the formation of a single embryonic outer envelope in A. limacoides, and that this takes place at a very early stage of embryogenesis. Their fusion results in the formation of a single continuous cytoplasmic layer surrounding the early embryo, which is composed of only a small number of undifferentiated blastomeres. The early separation of the macromeres may indicate an equal cleavage pattern. These results suggest that the systematic position of the Aspidogastrea among the Platyhelminthes still remains somewhat equivocal, and indicate the need for more studies on the embryonic development, larval morphogenesis and molecular phylogeny for the elucidation of the relationships between this enigmatic group and related taxa.     

Oxadiazols: a new class of rationally designed anti-human immunodeficiency virus compounds targeting the nuclear localization signal of the viral matrix protein

Despite recent progress in anti-human immunodeficiency virus (HIV) therapy, drug toxicity and emergence of drug-resistant isolates during long-term treatment of HIV-infected patients necessitate the search for new targets that can be used to develop novel antiviral agents. One such target is the process of nuclear translocation of the HIV preintegration complex. Previously we described a class of arylene bis(methylketone) compounds that inhibit HIV-1 nuclear import by targeting the nuclear localization signal (NLS) in the matrix protein (MA). Here we report a different class of MA NLS-targeting compounds that was selected using computer-assisted drug design. The leading compound from this group, ITI-367, showed potent anti-HIV activity in cultures of T lymphocytes and macrophages and also inhibited HIV-1 replication in ex vivo cultured lymphoid tissue. The virus carrying inactivating mutations in MA NLS was resistant to ITI-367. Analysis by real-time PCR demonstrated that the compound specifically inhibited nuclear import of viral DNA, measured by two-long terminal repeat circle formation. Evidence of the existence of this mechanism was provided by immunofluorescent microscopy, using fluorescently labeled HIV-1, which demonstrated retention of the viral DNA in the cytoplasm of drug-treated macrophages. Compounds inhibiting HIV-1 nuclear import may be attractive candidates for further development.     

Human dendritic cells transduced with herpes simplex virus amplicons encoding human immunodeficiency virus type 1 (HIV-1) gp120 elicit adaptive immune responses from human cells engrafted into NOD/SCID mice and confer partial protection against HIV-1 challenge

Small-animal models are needed to test human immunodeficiency virus (HIV) vaccine efficacy following viral challenge. To this end, we examined HIV-1-specific immune responses following immunization of nonobese diabetic-severe combined immunodeficient mice that were repopulated with human peripheral blood lymphocytes (hu-PBL-NOD/SCID mice). Autologous dendritic cells (DC) were transduced ex vivo with replication-defective, helper virus-free, herpes simplex virus type 1 (HSV-1) amplicons that expressed HIV-1 gp120 and were then injected into the hu-PBL-NOD/SCID mice. This resulted in primary HIV-1-specific humoral and cellular immune responses. Serum samples from vaccinated animals contained human immunoglobulin G that reacted with HIV-1 Env proteins by enzyme-linked immunosorbent assay and neutralized the infectivity of HIV-1 LAI and ADA strains. T cells isolated from the mice responded to viral antigens by producing gamma interferon when analyzed by enzyme-linked immunospot assay. Importantly, exposure of the vaccinated animals to infectious HIV-1 demonstrated partial protection against infectious HIV-1 challenge. This was reflected by a reduction in HIV-1(ADA) and by protection of the engrafted human CD4(+) T lymphocytes against HIV-1(LAI)-induced cytotoxicity. These data demonstrate that transduction of DC by HSV amplicon vectors expressing HIV-1 gp120 induce virus-specific immune responses in hu-PBL-NOD/SCID mice. This mouse model may be a useful tool to evaluate human immune responses and protection against viral infection following vaccination.     

Effect of hemagglutinin glycosylation on influenza virus susceptibility to neuraminidase inhibitors

Inhibition of neuraminidase (NA) activity prevents release of progeny virions from influenza-infected cells and removal of neuraminic (sialic) acid moieties from glycans attached to hemagglutinin (HA). Neuraminic acid moieties situated near the HA receptor-binding site can reduce the efficiency of virus binding and decrease viral dependence on NA activity for replication. With the use of reverse genetics technique, we investigated the effect of glycans attached at Asn 94a, 129, and 163 on the virus susceptibility to NA inhibitors in MDCK cells and demonstrated that the glycan attached at Asn 163 plays a dominant role in compensation for the loss of NA activity.     

Spore and micro-particle capture on an immunosensor surface in an ultrasound standing wave system

The capture of Bacillus subtilis var. niger spores on an antibody-coated surface can be enhanced when that coated surface acts as an acoustic reflector in a quarter wavelength ultrasonic (3 MHz) standing wave resonator. Immunocapture in such a resonator has been characterised here for both spores and 1 microm diameter biotinylated fluorescent microparticles. A mean spatial acoustic pressure amplitude of 460 kPa and a frequency of 2.82 MHz gave high capture efficiencies. It was shown that capture was critically dependent on reflector thickness. The time dependence of particle deposition on a reflector in a batch system was broadly consistent with a calculated time of 35 s to bring 95% of particles to the coated surface. A suspension flow rate of 0.1 ml/min and a reflector thickness of 1.01 mm gave optimal capture in a 2 min assay. The enhancement of particle detection compared with the control (no ultrasound) situation was x 70. The system detects a total of five particles in 15 fields of view in a 2 min assay when the suspending phase concentration was 10(4) particles/ml. A general expression for the dependence of minimum concentration detectable on; number of fields examined, sample volume flowing through the chamber and assay time shows that, for a practical combination of these variables, the threshold detection concentration can be two orders of magnitude lower.     

Hydrophobic drug delivery by self-assembling triblock copolymer-derived nanospheres

We describe the synthesis and characterization of a family of biocompatible ABA-triblock copolymers that comprised of hydrophilic A-blocks of poly(ethylene glycol) and hydrophobic B-blocks of oligomers of suberic acid and desaminotyrosyl-tyrosine esters. The triblock copolymers spontaneously self-assemble in aqueous solution into nanospheres, with hydrodynamic diameters between 40 and 70 nm, that do not dissociate under chromatographic and ultracentrifugation conditions. These nanospheres form strong complexes with hydrophobic molecules, including the fluorescent dye 5-dodecanoylaminofluorescein (DAF) and the antitumor drug, paclitaxel, but not with hydrophilic molecules such as fluorescein and Oregon Green. The nanosphere-paclitaxel complexes retain in vitro the high antiproliferative activity of paclitaxel, demonstrating that these nanospheres may be useful for delivery of the hydrophobic drugs.     

Neuroregulatory events follow adaptive immune-mediated elimination of HIV-1-infected macrophages: studies in a murine model of viral encephalitis

HIV-1-specific cellular immunity serves to eliminate infected cells and disease. However, how this process specifically affects the CNS is poorly understood. To mirror the regulatory events that occur in human brain after HIV-1 infection, a murine model of viral encephalitis was used to study relationships, over time, among lymphocyte-mediated infected cell elimination, innate immune responses, and neuropathology. Nonobese diabetic SCID mice were reconstituted with human PBL and a focal encephalitis induced by intracranial injection of autologous HIV-1-infected, monocyte-derived macrophages (MDM). On days 7, 14, and 21 after MDM injection into the basal ganglia, the numbers of human lymphocytes and mouse monocytes, virus-infected MDM, glial (astrocyte and microglial) responses, cytokines, inducible NO (iNOS), neurotrophic factors, and neuronal Ags were determined in brain by immunohistochemistry, real-time PCR, and Western blot assays. Microglia activation, astrocytosis, proinflammatory cytokines, and iNOS expression accompanied the loss of neuronal Ags. This followed entry of human lymphocytes and mouse monocytes into the brain on days 7 and 14. Elimination of virus-infected human MDM, expression of IL-10, neurotropins, and a down-regulation of iNOS coincided with brain tissue restoration. Our results demonstrate that the degree of tissue damage and repair parallels the presence of infected macrophages and effectors of innate and adaptive immunity. This murine model of HIV-1 encephalitis can be useful in elucidating the role played by innate and adaptive immunity in disease progression and resolution.