Affinity (tropism) of caprine arthritis encephalitis virus for brain cells.

One of the constraints in unraveling the mysteries blurring the advancement of research in the quest to totally put HIV problems under control is getting the appropriate animal model that would truly simulate human cases. This problem is more apparent in studies involving the central nervous system. Consequently, a viable animal model to generate information for the production of drugs and vaccines for the prevention and or control of lentiviral induced dementia in affected host animals is pertinent and vital. In this study, explant cultures prepared from the brain of new-born goat-kid were infected with CaprineArthritis Encephalitis (CAE) virus- a retrovirus affecting goats. The specific brain cell types infected by the (CAE) virus were determined using reverse-transcription polymerase chain reaction (RT-PCR) and transmission electron microscopy (TEM techniques). TEM showed that in 85 - 90% cases, microglia were the cells specifically infected by the virus. Amplification of the genomic sequence of the envelope and the gag genes by RT-PCR confirmed the presence of CAEV proviral DNA in the brain cells of affected animals. No productive infection of the astrocytes was observed. The results of this study showed a lot of similarities in the tropism of CAE virus infection of goat brain cells to that of HIV infection in humans thus suggesting the potential usefulness of the caprine model for the study of HIV neuropathology. The goat model system as a non-primate model therefore could be more adaptable as a simple animal model than primate models with their complexity of anthropological, environmental and safety problems.

The evaluation of non-specific cellular immunological parameters amongst children with Schistosoma haematobium infection in Nigeria.

This study used the leucocyte migration index to assess cellular immune function in children with urinary schistosomiasis. Migration inhibitory factor was produced (with other lymphokines) by sensitizing mitogens. The production of antigen-induced migration inhibitory factor in vitro correlated with the in vivo state of cellular hypersensitivity of the lymphocyte donor. The percentage positive leucocyte migration rate using three mitogens was least with inactivated measles haemagglutinin virus (IMV) and highest with Bacillus Calmette-Guerin (BCG) in the control group, while highest with tuberculin purified protein derivative (PPD) and least with IMV in the test group. The measurement of the migration index of leucocytes comparing the control with lightly- and heavily-infected children on activation using three mitogens was significantly reduced, except in the case of the control versus lightly-infected children using IMV. Using IMV, the leucocyte migration index for control versus lightly-infected children and heavily-infected children was significant (p > 0.002 and p < 0.001, respectively). Using BCG the difference between controls and lightly- and heavily-infected children were significant (p < 0.02). PPD showed no significant difference in leucocyte migration between control and the lightly- or heavily-infected children. In all leucocyte migration index decreased with intensity of infection except in the case of PPD (p < 0.002 for BCG; p < 0.001 for the IMV). There was a significant correlation between egg count and leucocyte migration index; for BCG (r = -0.20, p < 0.005); for IMV (r = -0.3, p < 0.001); for PPD (r = -0.38,p < 0.001). Patients with schistosomiasis infection can express normal and effective cellular immune responses to non-schistosomal antigens and also have equal immunological ability to combat pathogens as S. haematobium-free controls.

An outbreak of African Swine Fever in Nigeria: virus isolation and molecular characterization of the VP72 gene of a first isolate from West Africa.

The isolation of 98/ASF/NG, a strain of African Swine Fever Virus (ASFV) associated with a 1998 epizootic in Nigeria, is reported. This first isolate of the virus from West Africa was identified through a successful polymerase chain reaction (PCR) amplification and sequencing of a 280 base pair (bp) fragment of the Major Capsid Protein (VP72) gene. Further amplification and sequence analysis of a 1.9 kilobase pair (kbp) fragment encompassing the complete VP72 gene showed that the isolate has a 92.2%, 92.4%, and 97.2% homology with previously sequenced Ugandan, Dominican Republican and Spanish isolates respectively. Of the 50 nucleotide changes observed in this highly conserved gene, 45 were found to result in 40 amino acid changes clustered around the central region (position 426 to 516) of the VP 72 protein while changes at the remaining 5 positions were silent. These changes also led to the loss of two out of the seven potential N-glycosylation sites which are in this gene conserved among all isolates. The possible epizootiological implications of such mutations in a highly conserved gene of a DNA virus is discussed in relation to this outbreak.