The three envelope proteins of the hepatitis B virus (HBV) are encoded by a single open reading frame in the genome containing three separate in-phase AUG codons. This organization defines three protein domains (pre-S1, pre-S2, S) which form the small (S), middle (M, pre-S2/S), and large (L, pre-S1 /pre-S2/S) proteins. Mature virions are generated by the budding of preformed nucleocapsids through endoplasmic reticulum (ER) membranes containing S and L proteins, whereas the M protein is not necessary. This suggests an important function for the pre-S1 domain. To investigate the protein-protein interactions involved during the maturation process of the HBV virion, we studied in vitro the binding affinity to purified HBV core particles of various synthetic peptides identical to regions of the envelope proteins. Data previously obtained with deletion mutants were confirmed and refined. The 13 C-terminal amino acids of pre-S1 bound efficiently to core particles, whereas other pre-S domains did not. Moreover, the amino acid sequence 56-80 in the cytosolic loop of S bound efficiently to the HBV core. This double interaction between the HBV capside and both S and pre-S1 domains may be required for virion morphogenesis.

No abstract

Hepatitis delta virus (HDV) packaging requires prenylation of the HDV large protein (p27), as well as a direct protein-protein interaction between HDV proteins and hepatitis B virus (HBV) envelope protein domains. To investigate this interaction, we have analysed the binding capacity of baculovirusexpressed delta p24 and p27 proteins to synthetic peptides specific for the HBV envelope. Although a higher degree of binding was observed with p27, both p24 and p27 could bind HBV envelope peptides. One such peptide corresponded to residues 56-80 located in the cytosolic loop of the small HBV envelope protein, and another corresponded to 23 carboxy-terminal residues of the pre-S1 specific to the large HBV envelope protein. This indicates that in addition to p27, p24 may contribute to packaging of HDV through a proteinprotein interaction with HBV envelope domains, and that an interaction between the pre-S1 polypeptide and delta proteins may play a role in infectivity.Hepatitis delta virus (HDV), a satellite of hepatitis B virus (HBV), can cause fulminant hepatitis and liver cirrhosis in chronically infected patients (Rizzetto, 1983). The HDV virion is coated with an outer envelope composed of host cell-derived lipids and the envelope proteins of HBV. It surrounds an inner ribonucleoprotein (RNP) complex comprising a circular RNA genome and two proteins bearing the hepatitis delta antigen (HD Ag) : the small HD Ag (p24, 195 residues) and the large HD Ag (p27, 214 residues) (Wang et al., 1986 ; Weiner et al., 1988). They are encoded by the HDV genome and their sequences are identical except for 19 additional residues at the carboxy terminus of the large protein

Human immunodeficiency virus type 1 (HIV-1) may be studied by molecular or immunological approaches. Most analyses have been performed by genetic comparison of isolates and have led to the definition of clades or subtypes within the major (M) group of HIV-1. Five subtypes (A to E) were initially identified by comparison of genomic sequences. Four new subtypes (F to I) were identified more recently. Amino acid differences in the immunogenic V3 loop between isolates have also been studied, leading to a phenetic classification of at least 14 clusters (1 to 14) of sequences (B. T. M. Korber, K. McInnes, R. F. Smith, and G. Myers, J. Virol. 68:6730–6744, 1994). In this study, we compared the antigenicity of the V3 consensus sequences defined by phylogenetic analysis to the antigenicity of those defined by phenetic analysis. We used a recently developed subtype-specific enzyme immunoassay (SSEIA) that uses the principle of blocking with an excess of peptide in the liquid phase. Two SSEIAs were performed, the first with five V3 sequences defined by phylogenetic analysis and the second with 14 V3 sequences defined by phenetic analysis. A total of 168 HIV-1 sera taken from seropositive individuals from seven different countries or regions were studied. Experimental and statistical data, including correlation matrix and cluster analyses, demonstrated associations between the genetic subtypes and phenetically associated groups. Most of these were predicted by Korber et al. (J. Virol. 68:6730–6744, 1994) by theoretical analysis. We also found that V3 sequences can be grouped into between three and five antigenically unrelated categories. Residues that may be responsible for major antigenic differences were identified at the apex of the V3 loop, within the octapeptide xIGPGxxx, where x represents the critical positions. Our study provides evidence that there is a limited number of V3 serotypes which could be easily monitored by serological assays to study the diversity and dynamics of HIV-1 strains.

No abstract

No abstract

Hepatitis delta antigen (HDAg) is the only viral protein known to be expressed during hepatitis delta virus (HDV) infection. Detection of antibody to HDAg (anti-HD) is the usual method for diagnosis of HDV infection since viremia lasts only a few weeks. In an effort to identify the major epitopes recognized by humans during natural infection, four oligopeptides including residues 2 to 17 (SP1), 155 to 172 (SP2), 168 to 182 (SP3), and 189 to 211 (SP4) of the HDAg molecule were synthesized and probed by enzyme-linked immunosorbent assay with a panel of 80 serum specimens from 45 patients suffering from either HDV-hepatitis B virus coinfections (n = 17) or HDV superinfections (n = 28). Sera from infected patients recognized these relatively short peptides. Peptide SP2 was the most antigenic; 71% of serum specimens reacted. Antibody to SP2 was also the commonest in sera taken early in the course of the disease. Peptide SP2 corresponds to one of the two regions which is highly conserved between different isolates. Among the 63 serum specimens which scored anti-HD positive by a commercial assay, all but 3 reacted to at least one of the peptides (95% agreement). Peptide assays appeared to be significantly more sensitive than the commercial assay with native HDAg early in the course of HDV infection since 14 of 17 (82%) serum specimens which scored anti-HD negative in the commercial assay reacted to one or more peptides. All serum specimens giving one or more positive results with the various peptides were confirmed as being HDV positive by an inhibition assay with free peptide in solution. The immune response to HDAg peptides vared greatly between individuals. No specific reactivity profile could be assigned to those with either HDV-hepatitis B virus coinfections or HDV superinfections. Overall, HDAg peptides appeared to be convenient reagents in addition to native antigen for the development of new and improved diagnostic tests for HDV infection.

F. Poisson : docteur ès sciences. Ph. Roin geard : maître de confé re nces univers itaire, pra ticien hospitalier. A. Goudeau : pmfesseur des universites, praticien hospitalier. Département de microbtolo g ie médicale el moléculaire, Cnrs Ura 1 334, unité de virologie, CHU Bretonneau, 37044 Tours Cedex, France. m/s n• 10, vol. 11, urtu&Yf 95 2. Erlinger S. L'hépatite D. médecine/sciences 1985 ; 1 : 64-5. 3. Bréchot C. L'agent delta : biologie et p a thobiologie. médeci ne/sciences 1985 ; 1 : 66-8. 4. Bernuau J. Les hé p atites dues au virus D. méderine/sriences 1985 ; 1 : 69-73. 5. Branch AD, Le\�ne �J. Roberston HD. The brotherhood of circular RNA patho gens : viroids, circular satellites and the delta age nt. Semin Vi ral 1990 ; 1 : 143-52. 6. Diener TO. Autonomous and helper-de pendent small p athogenic RNAs of plants : \�raids and satellites. ln : Rizzetto M, Gerin JL, Purcell RH, eds. The ltejmtitis delta virus and its infrrtions. New Yo rk : Alan R Liss, 1987 : 3-18. 7. Bonino F, Heermann KH, Rizzetto M, Gerlich WH. Hepatitis delta virus : protein composition of de lta antigen and its he p ati tis B virus-derived em•elope. j Viral 1986 ; 58 : 945-50.