Analysis of the proteins of capripoxvirus (KS-1) revealed a 32kd protein that is one of the major structural proteins of the virus and is localised in the virus envelope. Monospecific serum prepared against the 32kd envelope protein neutralised the virus indicating that this protein contains neutralising epitopes. Lymphocyte proliferation studies, using the 32kd protein and peripheral blood mononuclear cells from capripoxvirus (KS-i) vaccinated sheep, showed that this protein strongly induced cellmediated immune responses. The 32kd protein is capripoxvirus specific and induced antibodies in early stages of capripoxvirus infections. Immunoblot analysis of antibody responses against this protein has provided a basis for the differential diagnosis of capripoxvirus and orf virus infections. The 32kd protein bound to the surface of cultured lamb testis cells. The binding of the 32kd protein was completely inhibited by prior incubation of cells with purified capripoxvirus (KS-1) but not by bovine serum albumin. Trypsin treatment of capripoxvirus (KS-1) degraded the majority of the 32kd protein with a minimal effect on a few other virus proteins. Trypsin removed an external 10kd fragment from the 32kd protein, leaving a 22kd fragment associated with the virus. In addition, the trypsin treatment reduced the virus infectivity by at least ten fold, suggesting that the cell surface binding domain of the 32kd protein is located within the external 10kd fragment. The monospecific serum to the 32kd protein had no effect of the infectivity titre of the trypsin treated virus further supporting the concept that the external 10kd fragment of the 32kd protein is involved in binding of the virus particle to the cell surface. A degenerate oligonucleotide probe, based on an internal amino acid sequence obtained from V8 protease cleavage products of the 32kd protein, was used to identify the gene encoding the 32kd protein. The gene encoding the 32kd protein was identified within the 2.8kb HindI1l Q1 fragment of the capripoxvirus (KS-1) genome. The nucleotide sequence analysis of the Hindu Q1 fragment revealed five open reading frames (Q11L, Q12R, Q13L, Q14R and Q15L), one of these open reading frames, Q13L, is capable of encoding a 30.6kd protein and contains the complete internal amino acid sequence obtained from the V8 protease cleavage products of the 32kd protein, indicating that the Q13L encodes the 32kd envelope protein of capripoxvirus (KS-1). The deduced amino acid sequence of the Q13L shows a 34.1% identity and 61.3% similarity with that of H3L open reading frame of vaccinia virus.

No description available.

No description available.

No description available.

No description available.

No description available.

Background. Numerous methods have been developed to model longitudinal data. In HIV/AIDS studies, HIV markers, CD4+ count and viral load are measured over time. Informative drop-out and the lower detection limit of viral load assays can bias the results and influence assumptions of the models. Objective The objective of this thesis is to describe the evolution of HIV markers in an HIV-1 subtype C acutely infected cohort of women from the CAPRISA 002: Acute Infection Study in Durban, South Africa. They were HIV treatment naive. Methods. Various linear mixed models were fitted to both CD4+ count and viral load, adjusting for repeated measurements, as well as including intercept and slope as random effects. The rate of change in each of the HIV markers was assessed using weeks post infection as both a linear effect and piecewise linear effects. Left-censoring of viral load was explored to account for missing data resulting from undetectable measurements falling below the lower detection limit of the assay. Informative drop- out was addressed by using a method of joint modelling in which a longitudinal and survival model were jointly linked using a latent Gaussian process. The progression of HIV markers were described and the effectiveness and usefulness of each modelling procedure was evaluated. Results. 62 women were followed for a median of 29 months post infection (IQR 20-39). Viral load increased sharply by 2.6 log copies/ml per week in the first 2 weeks of infection and decreased by 0.4 log copies/ml per week the next fortnight. It decreased at a slower rate thereafter. Similarly CD4+ count fell in the first 2 weeks by 4.4 square root cells/ul per week then recovered slightly only to decrease again. Left-censoring was unnecessary in this acute infection cohort as few viral load measures were below the detection limit and provided no improvement on model fit. Conclusion. Piecewise linear effects proved to be useful in quantifying the degree at which the HIV markers progress during the first few weeks of HIV infection, whereas modelling time as a linear effect was not very meaningful. Modelling HIV markers jointly with informative drop-out is shown to be necessary to account for the missing data incurred from participants leaving the study to initiate ARV treatment. In ignoring this drop-out, CD4+ count is estimated to be higher than what it actually is. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

No description available.

The potential application of weak acids for prevention of germ tube formation, a pathogenic process in <i>Candida albicans</i>, was examined. Previous departmental work revealed a rapid cytoplasmic alkalinization prior to germ tube formation in normal but not hyphal-minus strains, suggesting involvement of cytoplasmic alkalinization in dimorphism. Evidence that benzoate and sorbate can prevent germ tube formation and inhibit growth is given. This is probably due to their ability to shuttle protons across the plasma membrane perturbing intracellular pH control via the ATPase. Benzoate and sorbate could therefore provide an excellent and novel treatment for thrush infections based on a central cellular requirement, that of pH control. In addition they are relatively harmless, cheap and plentiful. The extent to which the azoles affect cellular functions other than ergosterol biosynthesis is unknown. Three separate effects have been identified here which suggest three target sites. High concentrations of azole result in cell death, intermediate concentrations in inhibition of germ tube extension and low concentrations in inhibition of dimorphism. It is already known that fluconazole inhibits cytoplasmic alkalinization and germ tube formation and that azoles inhibit the ATPase. This suggests a relationship between azoles and dimorphism which may be linked through their effect on intracellular pH by direct or indirect interference with ATPase activity. The occurrence of synergism between weak acids and the azoles has been confirmed. This provides the basis for work towards a novel treatment for thrush infections since synergistic relationships enhance effect and delay development of resistance. Growth of <i>Candida albicans</i> hyphae on a solid surface results in the production of a so far unreported coiled morphology. Investigations show that this is probably the result of tip rotation during apical extension which is revealed as a result of adherence to a solid surface. In addition evidence has been obtained of the frequency with which hyphae enter the random pores of Nucleopore membranes. This suggests the possibility (and emphasizes the need for investigation) of contact mediated responses in <i>Candida albicans</i>. Both hyphal coiling and the possibility of contact mediated responses are landmarks in pathogenicity studies of <i>Candida albicans</i>.

The persistence of infectious pancreatic necrosis virus (IPNV) in Atlantic salmon was examined with particular emphasis on the association of IPNV with leucocytes. Atlantic salmon were infected with IPNV via the water and via the feed. Despite relatively low mortalities, a high prevalence of IPNV was demonstrated particularly when the virus was introduced via the water. No virus-specific pathology or reduction in the growth performance of infected populations was evident. The conditions for the stimulation of Atlantic salmon leucocytes with the mitogen, phytohemagglutinin (PHA) were optimised and utilized in a co-stimulation assay. In this assay, leucocytes were infected with IPNV and simultaneously stimulated with PHA. It was demonstrated that the ability of IPNV to infect and replicate in leucocytes was enhanced when the cells were stimulated with mitogen. DNA synthesis was inhibited in the infected leucocytes. The inhibition was dependent upon the presence of infectious virus; inactivated virus failed to inhibit DNA synthesis. Three groups of salmon were examined to investigate the <i>in vivo</i> relationship of IPNV with leucocytes. Group A were the control group. IPNV was not isolated from these fish and the leucocytes responded to stimulation with PHA. Group B were experimentally infected IPNV carriers; virus was isolated from 6% of the fish using standard diagnostic methods but was not isolated from the supernatants of leucocyte cultures. The leucocytes of most fish responded to PHA stimulation. Neutralising antibody titres were variable and did not correlate with virus isolation. Group C were also IPNV carriers; virus could not be isolated using standard diagnostic methods but was isolated from the supernatants of stimulated leucocyte cultures of 44% of the fish. A significant inhibition of DNA synthesis in response to PHA stimulation was observed. The persistence of IPNV in Atlantic salmon is discussed in the light of the data presented here and existing knowledge of the persistence of mammalian viruses.