Evaluation of immunological methods for detection of bovine growth hormone (BGH) produced in E. coli

The use of several immunological methods for studies on synthesis of bovine growth hormone (BGH) by E. coli is described here. The ELISA procedure was shown to be the least sensitive and unfit for assaying BGH in E. coli extracts. The solid-phase radioimmunoassay (RIA) proved to be highly sensitive, but since E. coli extract itself (not containing BGH) interfered with the immunological reaction, its use for measuring BGH was practically limited. The best adequate procedure proved to be radioimmunoassay in solution, which was not adversely affected by the E. coli extract and was sufficiently sensitive to detect nanogram quantities of BGH. The size of the BGH produced by normal bacterial cells was investigated by protein fractionation, transfer to nitrocellulose paper and detection by anti-BGH serum. This method was also served for semi-quantitative determination of BGH in the bacterial extract.