[HIV-1 neuropathogenesis: therapeutic strategies against neuronal loss induced by gp120/Tat glycoprotein in the central nervous system]. / Neuropatogenesis inducida por el virus del sida: estrategias terapeuticas frente a la neurodegeneracion inducida por la glucoproteina gp120/Tat en el sistema nervioso central.

Neuroinflammation is a key process in the neuropathogenesis of AIDS virus since as a result of the aberrant activation of the chemokine receptors (CXCR4, CX3CR1 and CR5) produces proinflammatory cytokine release by infected cells, increases microglial neurotoxicity and generates lipoperoxides and reactive oxygen species (ROS) that eventually damage the neuron. Moreover, the neurotoxin Tat produces dendritic loss by interacting with the low-density lipoprotein receptor (LRP) and also overstimulates N-methyl D-aspartate receptors (NMDA). Furthermore, the aberrant interaction of glycoprotein gp120 with the CXCR4 chemokine receptor causes caspase-3-dependent apoptosis (ceramide is also released) activating apoptotic proteins (p53 and retinoblastoma), which are part of the neurotoxic mechanisms associated to neuronal dysfunction in neuroAIDS. Similarly, gliosis/microglial activation and the release of neurotoxic factors by infected monocytes with elevated amounts of certain chemokines in the cerebrospinal fluid (MCP-1 and fractalkine, among others) contribute to the neuropathogenesis of HIV-1. Alpha-synuclein and beta amyloid deposits have also been detected in post mortem brains of seropositives patients. In addition, there are studies have detected several systemic markers related with the degenerative effects of the virus and its neurotoxins on the central nervous system; such as osteopontin, CD163 and fractalkine, among others. Lastly, clinical trials have been conducted using protective strategies related that attempt to inhibit apoptotic proteins (GSK-3 beta), microglial activation inhibitors (minocycline), antioxidants (selegiline) or trophic factors (IGF-1, growth hormone or erythropoietin). These trials have shown that their treatments are beneficial and complementary to treat complications of HIV/AIDS.

Plaque assay for African swine fever virus on swine macrophages.

A plaque assay developed to detect the infection of African Swine Fever Virus on swine macrophages is described. Plaques were generated by all of the virus isolates tested. The method is suitable not only for virus titration but also for the selection of clones in protocols for isolation/purification of recombinant viruses.

African swine fever virus EP153R open reading frame encodes a glycoprotein involved in the hemadsorption of infected cells.

The open reading frame EP153R, located within the EcoRI E' fragment of the African swine fever (ASF) virus genome, is predicted to encode a membrane protein of 153 amino acids that presents significant homology to the N-terminal region of several CD44 molecules. EP153R contains multiple putative sites for N-glycosylation, phosphorylation, and myristoylation, a central transmembrane region, a C-type animal lectin-like domain, and a cell attachment sequence. Transcription of EP153R takes place at both early and late times during the virus infection. The disruption of the gene, achieved by insertion of the marker gene LacZ within EP153R, did not change either the in vitro virus growth rate or the virus-sensitive/resistant condition of up to 17 established cell lines, but abrogated the hemadsorption phenomenon induced in ASF virus-infected cells. As the sequence and expression of the ASF virus protein pEP402R, a CD2 homolog responsible for the adhesion of erythrocytes to susceptible cells, was unaffected in cultures infected with the EP153R deletion mutant, we conclude that the gene EP153R is needed to induce and/or maintain the interaction between the viral CD2 homolog and its corresponding cell receptor.

Virus-specific cell receptors are necessary, but not sufficient, to confer cell susceptibility to African swine fever virus.

The entry of African swine fever (ASF) virus into Vero cells and swine macrophages is mediated by saturable binding sites located in the plasma membrane, which have been related, as in other virus-cell systems, to the sensitivity of the cell to the virus. In order to define this correlation, we have analyzed up to 16 cell lines derived from different species for their sensitivity to virus infection, to determine the step in the virus infective cycle that was blocked in each resistant cell, the presence of saturable cell receptors and the percentage of bound and internalized virus in these cells. Specific ASF virus receptors were found in different quantities in many sensitive and resistant cell lines. The most restricted cells showed a reduced efficiency of virus binding and virus internalization, as well as a lower amount of cell receptors for the virus attachment protein p12. Other resistant cells were restricted only after early virus translation or virus DNA replication, proving that the presence of virus-specific receptors may be necessary, but not sufficient, to guarantee the cell permissiveness to the virus, and that the ASF virus infection can be arrested at different steps on the infective cycle.