Characterisation of epitopes on barley mild mosaic virus coat protein recognised by a panel of novel monoclonal antibodies.

Barley mild mosaic virus (BaMMV), a member of the family Potyviridae, genus Bymovirus, is involved in the economically important yellow mosaic disease of winter barley in East Asia and Europe. We investigated serological properties of bacterially expressed BaMMV coat protein (CP) of a German isolate. Ten mouse monoclonal antibodies were produced using purified E. coli expressed BaMMV-CP as immunogen. The reactivity of MAbs with different strains of BaMMV was analysed by several immunological methods that are frequently used in diagnostic virology: enzyme-linked immunosorbent assay (ELISA), dot-blot, Western-blotting (WB), direct tissue blotting immunoassay (DTBIA) and immunoelectron microscopy (IEM). The amino acids involved in the formation of epitopes recognised by several MAbs were mapped by using synthetic pin-bound peptides and the localisation of epitopes in assembled virus particles was determined by electron microscope studies. MAbs V29 and M1 decorated the whole virion indicating that their epitopes 6PDPI9 and 96ITDDEK101, respectively, are exposed on the surface. The MAbs V6 and V14 both interacted with 44LPEPKM49, which seems to be accessible at only one end of the virus particle. The MAbs V6, V14, V29 and M1 detected epitopes common to a wide range of BaMMV isolates and can therefore be used effectively in routine diagnostic tests for BaMMV from barley leaves. We suggest that MAbs M1, V6, V14 and V29 are most suitable for use in TAS-ELISA, V6, V14 and V29 for Western blotting and V29 and M1 for electron microscope serology.

Dynamics of the HIV-1 variability in adults from Bucharest, 1992-1998.

Variability is a hallmark of HIV viruses both at the genetic and the phenotypic level. Viral sequencing and phylogenetic analysis of many isolates revealed specific distribution of HIV-1 subtypes according to the geographic location and route of transmission. In Romania, the currently available data coming from the study of pediatric HIV infection suggest the predominance of subtype F. However, there are few data concerning the distribution of HIV-1 subtypes among adults. We investigated the changes in the distribution of different HIV-1 subtypes among HIV-1 infected adult patients from Bucharest over a 6 years period (1992-1998) by means of V3 binding assays. The analysis of the relative incidence of different HIV-1 serotypes revealed the steady predominance of serotype F (50-75%) among the adults from Bucharest and a small but constant increase of the number of samples with serotype B- from 5% in 1994 to 14% in 1998. In contrast, the serotype E is either absent or weakly represented (4%) during the period of the study. All over the years there was a relatively high proportion (6-30%) of non-reactive samples. This could be an indication for the possible emergence of new or recombinant HIV-1 subtypes.