Purification of inclusion body—forming peptides and proteins in soluble form by fusion to Escherichia coli thermostable proteins

Proteins and peptides expressed in the prokaryotic system often form inclusion bodies. Solubilization and refolding procedures can be used for their recovery, but this process remains difficult. One strategy for improving the solubility of a protein of interest is to fuse it to a highly soluble protein. To select a suitable fusion partner capable of solubilizing the aggregation-prone (inclusion body–forming) proteins and peptides, Escherichia coli thermostable proteins were identified and tested. Among them, trigger factor (TF) protein was selected because of its high expression and stability. Using an expression system based on fusion to TF, selected proteins and peptides that otherwise form inclusion bodies were expressed in soluble state and were purified like other soluble proteins. This system provides a convenient method for production of aggregation-prone proteins and peptides.

High level expression of surface glycoprotein of rabies virus in tobacco leaves and its immunoprotective activity in mice

A synthetic gene coding for the surface glycoprotein (G protein) of rabies virus was strategically designed to achieve high-level expression in transgenic plants. The native signal peptide was replaced by that of the pathogenesis related protein, PR-S of Nicotiana tabacum. An endoplasmic reticulum retention signal was included at C-terminus of the G protein. Tobacco plants were genetically engineered by nuclear transformation. Selected transgenic lines expressed the chimeric G protein at 0.38% of the total soluble leaf protein. Mice immunized intraperitoneally with the G protein purified from tobacco leaf microsomal fraction elicited high level of immune response as compared to the inactivated commercial viral vaccine. The plant-derived G protein induced complete protective immunity in mice against intracerebral lethal challenge with live rabies virus. The results establish that plants can provide a safe and effective production system for the expression of immunoprotective rabies virus surface protein.

Pasteurella gallinarum neonatal meningitis

A 4-day-old baby weighing 1.7 kg was admitted to the neonatal intensive care unit of Ga-Rankuwa Hospital, Pretoria, with a history of apneic attacks. On examination there was an umbilical sepsis and the neonate was septicemic. The baby had been delivered at home and the umbilical cord had been cut by the grandmother using unclean scissors and chimney soot applied to the umbilical stump. On admission, a septic screen was done and antibiotic treatment was started with penicillin and amikacin. The investigations showed that the baby was slightly anemic, with hemoglobin levels of 10.0 g/dL (14.9-23.7 g/dL), and a pure growth of a Gram-negative bacillus was obtained from the cerebrospinal fluid, blood culture and suprapubic aspirate urine specimens. The Gram-negative bacillus was catalase and oxidase positive and it was identified as Pasteurella gallinarum. Antimicrobial profiling showed the organism to be susceptible to penicillin, cefotaxime, gentamicin and amikacin. Despite having received antimicrobial agents to which the etiological agent was susceptible, the neonate died within 5 days of admission. The cause of death was postulated to be due to overwhelming sepsis which resulted in septic shock.

Episodic cervical dystonia associated with gastro-oesophageal reflux. A case of adult-onset Sandifer syndrome

Sandifer syndrome is a dystonic movement disorder described in children with severe gastro-oesophageal reflux. We now report a patient who had the features of Sandifer syndrome first developing in adult life. Onset of dystonic episodes followed closely the occurrence of a Bell's palsy, while symptoms of peptic oesophagitis had been present for several months beforehand. Successful symptomatic treatment of gastro-oesophageal reflux was accompanied by cessation of the dystonic episodes. Possible pathophysiological mechanisms of the abnormal movements in Sandifer syndrome are discussed.