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M J Frost

Publications and source records attributed to M J Frost.

3 recordsLinked to original sources
PubMed2002

A single amino acid is critical for the expression of B-cell epitopes on the helicase domain of the pestivirus NS3 protein.

Truncated NS3 proteins, expressed by recombinant baculoviruses, were used to investigate the location of conserved B-cell epitopes on this non-structural bovine viral diarrhoea virus (BVDV) protein. A goat anti-pestivirus antiserum, and a panel of anti-NS3 monoclonal antibodies, including the BVDV-1 specific antibody P1D8, were used to verify the presence or absence of the epitopes. Interestingly, the monoclonal antibodies reacted only with the truncated protein encompassing the helicase domain of NS3. Expression of the B-cell epitopes was dependent on, but not within, a 57 amino acid sequence at the carboxy-terminal end of this protein, supporting observations that these conserved epitopes are conformational in nature. A comparison of deduced amino acid sequences of the helicase domain from BVDV-1, BVDV-2, BDV and CSFV isolates highlighted a single amino acid that appeared to be unique to P1D8-reactive BVDV-1 isolates. Site-directed mutagenesis studies confirmed that this amino acid is critical for the expression of the BVDV-1 specific NS3 epitope recognised by the P1D8 monoclonal antibody. Surprisingly, the amino acid was also important for an epitope recognised by two group-specific monoclonal antibodies, P1H11 and P4A11. Protein modelling studies, based on the structure of the hepatitis C NS3 helicase domain, indicated that this amino acid occupies a prominent position on the surface of the protein.

Amino Acid Substitution↗
PubMed1975

Extraction and preliminary characterization of a human bronchogenic carcinoma antigen.

Saline extracts of human bronchogenic tumours, soluble in 50% saturated ammonium sulphate and also fractions from Sephadex G-200 chromatography were used to raise antisera in rabbits. After absorbing the antisera with normal tissue extracts, direct Ouchterlony tests were performed against tumour (adenocarcinomata and squamous cell carcinomata) and normal extracts. A precipitin reaction was given with all 11 tumour extracts tested at a concentration of 5 mg/ml whereas all the 9 normal lung control extracts did not react at concentrations up to 100 mg/ml. The possibility that this reaction could be related to histocompatibility differences between individuals is ruled out by the fact that in two cases tumour and normal tissue were obtained from the same patient. These studies and also precipitin-inhibition experiments have confirmed the existence of antigen associated with bronchial carcinomata and have shown that, although the antigen or a cross-reacting antigen is present in normal lung tissue, the amounts are small in comparison with the amounts extracted from tumour. Antigenic activity was contained in a single absorbance peak when fractionated by Sephadex G-200 chromatography and its elution volume indicated a molecular weight of approximately 4-0 times 10(4)D. Further purification was achieved using isotachophoresis. Preliminary characterization of the antigen has shown it to be stable at pH 4-5, resistant to heating at 50 degrees C for 30 min, to migrate on immunoelectrophoresis with a cationic mobility at PH 8-5 and to be immunologically distinct from carcinoembryonic antigen.

Adenocarcinoma↗