Sindbis Research Articles

A study of nucleotide sequence homology between the nucleic acids of different alphaviruses

Base sequence homologies have been analyzed between the virus-specific nucleic acids of the four different alphaviruses, Semliki Forest (SF) virus, Sindbis (SIN) virus, Chikungunya (CHIK) virus, and O'nyong-nyong (ONN) virus and between different strains of these viruses by RNA-RNA hybridization experiments and by two-dimensional gel electrophoretic analyses of the oligonucleotides generated by RNase T 1 digestion. The following results were obtained: (1) Similar to earlier findings in SIN and SF virus-infected cells two species of single-stranded virus-specific RNA sedimenting at about 42 S and 26 S on sucrose density gradients, respectively, are synthesized in ONN and CHIK virus-infected cells and the 26 S RNA molecules are subgenomic RNA species. (2) Different oligonucleotide patterns were obtained for the genome RNA molecules of the different viruses and none of the oligonucleotides characterized was present in more than one of the viruses. (3) Besides a large number of common oligonucleotides, differences were found in the oligonucleotide patterns of different strains of the same virus, which allowed the identification of the virus strain from the oligonucleotide pattern of its genome RNA. (4) A 13% base sequence homology was detected between CHIK virus and ONN virus by RNA-RNA hybridization, whereas only small sequence homologies of about 1% or less were detected between the other viruses.

Inhibition of group B arbovirus antigen production and replication in cells enucleated with cytochalasin B.

A comparative study of the growth of Sindbis (SIN) virus, a group A arbovirus (togavirus), and Japanese encephalitis (JE) virus, a representative group B arbovirus (togavirus), was conducted in enucleate and nucleate cells. Immunofluorescent tests and yield measurements demonstrated that chicken embryo cells which had been enucleated and subsequently infected with SIN virus produced virus-specific antigens and infectious virus. By contrast, JE failed to replicate or produce virus-specific antigen in cells which had been enucleated before or even 2 h post infection. Studies of the effect of enulceation at various times after infection demonstrated that a nucleus must be present at least 2 and possibly as long as 4 h after infection to produce either JE-specific antigen or infectious JE virus. These studies demonstrate that the replication of SIN, a group A arbovirus (togavirus), which has no nuclear requirement, contrasts sharply with that of a group B arbovirus (togavirus), JE, which may have an initial dependence on a nucleus-associated process.

Live and killed adenovirus vaccines for the prevention of acute respiratory disease in recruits.

Concomitant infection of HeLa cells with poliovirus and Sindbis (SB) virus allowed replication of poliovirus only. The poliovirus-induced interference with the replication of SB virus was dependent partially on the multiplicity of SB virus used for infection. The observed interference was not sensitive to guanidine. Translation, but not replication of poliovirus, appears to be needed for the restriction of SB virus. Superinfection of SB virus-infected cultures with poliovirus was followed by inhibition of protein, but not by viral ribonucleic acid (RNA) synthesis. Polyribosomes present in SB virus-infected cells were disaggregated subsequent to superinfection. The nascent SB viral RNAs synthesized in cells subsequent to superinfection were not associated with the ribosomal structures. These results indicate that the block in protein synthesis, possibly at the level of initiation, may be the basis of the observed interference.

Antigenic components of group A arbovirus virions.

Three group A arboviruses, Sindbis (SIN), western (WEE) and eastern equine encephalitis (EEE), were selectively degraded with a nonionic detergent to yield a core particle and a soluble envelope component. Antigenic analysis by using radioimmune precipitation techniques revealed marked antigenic similarity among the core particles of the three viruses. The soluble envelope component exhibited antigenic specificity similar to that of intact virions. A close relationship between SIN and WEE envelopes was shown, whereas EEE envelope antigen appeared antigenically specific. These data indicate that nucleocapsids of group A arboviruses contain an antigenic determinant common to the group; the envelope contains virus-specific antigens as well as antigens which relate members of a subgroup.

Radioimmune Precipitation of Group a Arboviruses

Abstract A radioimmune precipitation (RIP) test was used to study selected group A arboviruses. Purified preparations of Sindbis (SIN), western equine encephalitis (WEE) and eastern equine encephalitis (EEE) virus were examined in homologous and heterologous reactions. RIP reactions were comparable to plaque reduction neutralization tests in both sensitivity and specificity. When SIN virus was precipitated by WEE virus antiserum, the RIP curve was biphasic. RIP inhibition of the homologous and biphasic heterologous reaction suggested three separate antibody populations of differing specificities. The results indicated that WEE virus antiserum contained: a) a high titered specific antibody, b) a broadly crossreactive antibody at intermediate antiserum dilutions and c) a low titered antibody which detected only the intra-group WEE-SIN virus complex.