Metacyclic form-specific variable surface glycoprotein-encoding genes of Trypanosoma (Nannomonas) congolense

A complementary DNA expression library in phage lambda gt11 was synthesized using mRNA from in vitro-produced metacyclic forms of a clone of Trypanosoma (Nannomonas) congolense. The unamplified library was screened with antiserum from a goat immune to infection with metacyclic (m)-forms of T. congolense ILRAD Nannomonas antigen repertoire 2(ILNaR2). Of the 100 antiserum-reactive phage clones identified, 22 were analyzed further: 21 of the clones contained overlapping portions of a single transcript, while one other contained a different transcript. Northern blot analyses indicated that the sequences contained in the clones were transcribed only by m-forms of ILNaR2. Immunological and sequence analyses indicated that the two different cloned sequences encode m-form-specific variable surface glycoproteins.