- Volume 65, Issue 10, 1984

K-104 cells, a cloned cell line derived from a human neuroblastoma (SYM-I), were induced by rabies HEP-Flury virus to release large amounts of interferon, and the resulting antiviral activity significantly suppressed the rabies virus replication. The role of endogenous interferon was confirmed by treatment with anti-interferon antibody which increased the yield of progeny virus. The virus yield in the second undiluted passage through K-104 cells was much less than that in the first passage, because of the antiviral state initiated by brief contact of interferon present in the virus inoculum with cells during the short period of virus adsorption. When the m.o.i. was relatively low, as in the third undiluted passage, the effect of interferon present in the inoculum was enhanced and most of the infected cells survived but were shown to be in a state of persistent infection. Defective interfering (DI) particles did not accumulate rapidly during these three undiluted passages. When Sindbis virus was used for infection, the endogenous interferon system of K-104 cells was not activated during 12 undiluted passages. However, on the 12th passage, the yield began to decline due to the generation and accumulation of DI particles.

An inhibition radioimmunoassay and a two-site immunoradiometric (four-layer) assay for the quantification of measles virus nucleocapsid antigen were established and their sensitivities compared. Both assays exhibited threshold sensitivities of from 1 to 10 ng nucleocapsid antigen per ml. Concentrations of reagents used in the assays were shown to be an important factor determining the sensitivities of the assays. Purified mumps or parainfluenza 2 virus nucleocapsids did not compete with measles virus nucleocapsids in the inhibition assay but some degree of cross-reactivity with canine distemper virus nucleocapsid was observed. Pretreatment of virus-infected cells with detergent had a significant effect on the amount of antigen detectable by the assays. SDS greatly decreased the reactivity of measles virus nucleocapsid but Triton X-100 and, to a larger degree, sodium deoxycholate released antigen from the cells in quantities greater than that detected when no detergent pretreatment was employed. Complexing of antibodies to measles virus nucleocapsids in vitro decreased dramatically the threshold sensitivity of the nucleocapsid assays. The antigen-antibody complexes could be disrupted and the components separated but the conditions employed destroyed 90% of the antigenic reactivity of the nucleocapsid and also had a deleterious effect on the antibody. Nucleocapsid antigen was readily detected in brains from hamsters with acute measles encephalitis. The assays, however, were not sensitive enough for routine detection of antigen in brains from hamsters with chronic measles encephalitis.

Infectious virus could no longer be detected in the trigeminal ganglia removed from mice 25 days after infection with herpes simplex virus type 1 (HSV-1) by the lip route. When the ganglia were cultured in vitro for 1 or 2 days, infectious HSV-1 was again detected in the ganglia, indicating the reactivation of latent HSV-1. The effect of indomethacin on this reactivation was examined. When the ganglia were cultivated in the presence of 5 × 10−4 m-indomethacin, the appearance of infectious virus in the ganglia was almost completely inhibited. After removal of indomethacin, infectious virus appeared and the virus titre reached levels found in the ganglia cultured in indomethacin-free medium, indicating that the inhibition of the reactivation may not be due to the cytotoxic effect of indomethacin on the ganglionic cells. The inhibitory effect of indomethacin was only seen when it was added shortly after explantation. These results suggest that indomethacin affects some early processes of viral reactivation in the explanted ganglia. The synthesis of prostaglandins (PGE and PGB) found in the explanted ganglia was strongly suppressed by indomethacin, as was the viral reactivation. Other inhibitors of prostaglandin synthesis, i.e. tetracaine, mepacrine and mefenamic acid, also inhibited viral reactivation in the explanted ganglia. These results suggest that the inhibitory effect of indomethacin on the reactivation of latent HSV-1 may be due to the inhibition of prostaglandin synthesis, although it is possible that other cellular changes which could be caused by indomethacin contributed to the suppression of reactivation.

The influence of the T-lymphocyte-stimulating dipeptide bestatin on the induction of neutralizing antibodies against herpes simplex virus type 1 in the mouse was investigated. dose—response experiments revealed two active ranges from 1 ng/kg to 100 ng/kg and from 10 µg/kg to 10 mg/kg or more. Bestatin (10 mg/kg) enhanced antibody levels after primary infection, if injected between day 5 and day 8 after infection with a maximum effect at day 5. Following secondary infections, bestatin was most effective at day 1 after secondary infection. Moreover, the antibody-generating potency of a formalinized herpes simplex virus type 1 vaccine was elevated considerably. Bestatin and silica seemed to be effective systemically. Treatment of mice with silica before virus infection and additionally with bestatin at day 1 after infection resulted in an additive effect on antibody production. Comparable effects could be obtained when polyinosinic acid. polycytidylic acid or indomethacin was combined with bestatin at day 1. It was assumed that certain factors released by macrophages ‘sensitize’ the antibody-producing system for the enhancing activity of bestatin at day 1. Indeed, culture fluids of macrophages obtained from mice either pretreated with silica or infected by herpes simplex virus were active in enhancing antibody formation upon injection into mice at day 1 in combination with bestatin. Bestatin did not induce interferon activity. No influence of bestatin on the virus content of organs or on mortality was observed.

Vaccinia virus WR induces an immediate and rapid inhibition of HeLa S3 cell RNA synthesis as determined by pulse-labelling with [3H]uridine. The inhibition was independent of the purity of the infecting virus preparation and the multiplicity of infection over the range of 4 to 200 pk.f.u./cell. Inhibition was not evident in cells pretreated with cycloheximide or following infection with u.v.- or heat-inactivated virus, suggesting that viral protein synthesis was required. There was no apparent selective inhibition of any particular species of RNA. Following infection, the uptake of [3H]uridine into cellular pools and the subsequent biosynthesis of UTP proceeded at the same rate as in mock-infected control cells. The rate of degradation of pre-labelled RNA was not enhanced in infected cells compared to controls. Analysis of the nuclear DNA-dependent RNA polymerase (EC 2.7.7.6) activities revealed a progressive and eventually total loss of RNA polymerase B activity, no obvious effect on RNA polymerase A and the presence of a viral RNA polymerase, the possible significance of which is discussed.

The DNA of simian adenovirus SA7P was cloned in pBR322. The nucleotide sequences of the leftmost 2238 bp and the rightmost 188 bp of the viral genome were determined. SA7P DNA has an inverted terminal repeat of 183 bp. The sequence at the left terminus exhibits extensive homology with that of the E1 regions of human adenovirus 5, 7 and 12 DNAs. Based on this homology, the RNA coordinates and coding regions could be deduced. The sequenced SA7P DNA contains the entire E1A and part of the E1B region.

Antigenic and structural variation in the major nucleocapsid protein, VPN41, from different strains of respiratory syncytial (RS) virus was observed using a combination of monoclonal antibodies and two-dimensional peptide mapping. Limited trypsin treatment of intact nucleocapsids produced two peptide fragments M r 27K and M r 14K. Two monoclonal antibodies, N1 and N2, reactive with primary sequence epitopes located on intact nucleocapsids also reacted with either the 27K fragment (N2) or the 14K fragment (N1). Competitive radioimmunoassay studies using N1 and N2 antibodies revealed two discrete antigenic groups among the seven human strains of RS virus examined. A bovine strain of RS virus, although antigenically similar to the human strain of RS virus, was placed in a separate group. Two-dimensional peptide mapping of 125I-labelled VPN41 purified by SDS-PAGE revealed extensive structural homology between all strains. However, several unique tryptic/chymotryptic peptides supported the grouping obtained with the monoclonal antibodies.

The effect of glucocorticoid hormones on the replication of human cytomegalovirus (HCMV) was studied in human embryonic lung (HEL) cells. Treatment of cells with pharmacological concentrations of adrenal glucocorticoids such as dexamethasone enhanced HCMV replication; treatment with oestrogenic or androgenic hormones did not do so. In dexamethasone-treated HEL cells there was an approximately tenfold increase in virus yield, with the virus eclipse period shortened by 1 day compared to control cultures. Treatment of cells with the hormone also enhanced plaquing efficiency of the virus by approximately tenfold. As the synthesis of virus-specific immediate early proteins and antigens was notably enhanced together with an increase of HCMV DNA synthesis, it appeared that the early stages of the HCMV replication cycle might be under hormonal control. Moreover, the data presented suggest that the hormonal enhancement of HCMV replication involves specific receptor proteins and requires the synthesis of a specific cellular mRNA(s).

Seventeen temperature-sensitive mutants of the Concan subtype of the New Jersey serotype of vesicular stomatitis virus have been isolated following mutagenesis and assigned to two complementation groups: CC/A, containing three mutants, and CC/B, containing 14 mutants. Prototype mutants of these two Concan groups efficiently complemented prototype mutants of the Hazelhurst complementation groups (with the exception of the corresponding group) which correspond to genes specifying the L, N, M and NS proteins. The pattern of intersubtypic complementation allowed the correlation of the Concan CC/B group with the Hazelhurst B group (L gene) and of the Concan CC/A group with the Hazelhurst A group (N gene). In contrast, the Concan prototype mutants failed to complement the prototype mutant of each of the five Indiana complementation groups for which genetic assignments have been made. The partitioning of intracellular nucleocapsids of the Concan and Hazelhurst subtypes during isolation was identical, and distinct from that of Indiana serotype intracellular nucleocapsids. The M protein of the Concan, but not of the Hazelhurst, subtype was observed to migrate as a doublet on SDS-polyacrylamide gels electrophoresed in a phosphate buffer.

Human B-cell lines, designated ATLB cell lines, were spontaneously established from peripheral blood of adult T-cell leukaemia (ATL) patients. The cell lines consistently expressed ATL-associated antigen (ATLA) and Epstein—Barr virus-associated nuclear antigen (EBNA). A cloned ATLB line, designated ATLB 2, showed that both ATLA and EBNA antigens were present in the same B-cell clone. In this study, we have further characterized ATLV and EBV in the cloned ATLB 2 cell line by biochemical techniques. The ATLA antigens in these clones, initially shown by immunofluorescence, were studied by immunoprecipitation with human sera from ATL patients and the Western blotting technique using a mouse monoclonal antibody (GIN-14). We identified ATLV core polypeptides 24K and 19K in the ATLB cell extracts. Furthermore, total cellular DNA and poly(A) RNA from the ATLB cell lines were analysed for the presence of viral genomes with molecularly cloned DNA probes containing the ATLV and EBV sequence, respectively. The results showed that all ATLB 2 clones contained highly conserved ATLV proviral DNA irrespective of whether or not they expressed ATLA. They also contained several copies of EB virus DNA and DNA—DNA reassociation kinetics studies clearly showed that most of the EBV DNA sequences were present in ATLB cells. ATLV-related mRNA was detected in only ATLA-positive clones (ATLB 2-3 and 2-21) but not in a negative clone (ATLB 2-45).

The proteins of a highly leukaemogenic murine virus (DMBA-LV) endogenous to the CFW/D mouse have been characterized. This virus does not contain ecotropic, xenotropic or polytropic type C retroviruses capable of replicating in established tissue culture cell lines. Analysis of the viral proteins indicated that proteins characteristic of both type C and type B retroviruses were present. All the proteins characteristic of a competent, mature type B retrovirus, such as the murine mammary tumour virus, were present in the virions and were expressed at high levels in a virus-producing thymic lymphoma cell line. Type C internal structural proteins were detected in the virus and cells producing virus. Type C envelope protein was detected at very low levels in both the virions and the virus-producing tumour cell lines. Chymotryptic polypeptide profiles of this gp70 indicated similarity with the envelope glycoproteins characteristic of xenotropic and recombinant type C retroviruses.

Chick embryo lethal orphan (CELO) virus (fowl adenovirus type 1) contains at least 14 structural proteins with polypeptide molecular weights ranging from 100K to about 6K. A nomenclature of the CELO virion polypeptides is presented and the molar proportion of each polypeptide has been estimated. The CELO virus pentons were specifically released from the virion by dialysis against borate-based calcium-magnesium saline. The penton base (polypeptide III, mol. wt. 92K) and two fibres were separated, characterized and their polypeptides were correlated with their morphological positions in the virion. Peptide mapping suggested that the long fibre (polypeptide IV, mol. wt. 65K), and the short fibre (polypeptide VII, mol. wt. 44.5K) were not related in their primary sequences and are therefore probably encoded by separate genes. The time course of synthesis of the CELO virion polypeptides indicated that, like their mammalian adenovirus counterparts, they are synthesized late (after viral DNA replication).

Chick cells infected by chick embryo lethal orphan (CELO) virus (fowl adenovirus type 1) contained four prominent virus-specific, structurally related DNA-binding proteins with mol. wt. of 74K, 64K, 56K, 52K, and two minor forms. The CELO virus DNA-binding proteins were phosphorylated, delayed-early nuclear proteins. CELO virus early proteins were expressed in BHK cells, but did not complement human adenovirus type 5 mutants with lesions in E1A, E2A or E2B. Moreover, CELO virus DNA-binding proteins were not produced in 293 cells, which express human adenovirus E1 genes. These results suggest that activation of transcription by adenovirus E1A genes involves specific interactions between the E1A gene products and viral early promoters.

Evidence is presented that defective interfering (DI) Semliki Forest virus (SFV) can modulate the systemic infection in mice initiated by intraperitoneal inoculation of 10 LD50 SFV. Either the mean time of death was delayed or mice failed completely to develop any sign of disease. This prophylactic activity of DI virus was not due to the stimulation of an adaptive immune response since an equivalent amount of non-infectious virus antigen did not change the course of disease.

Culture supernatants of permissive and non-permissive cells infected with human cytomegalovirus (HCMV) contain a growth factor that enhances the DNA synthesis and mitotic activity of target cells. This cytomegalovirus growth factor (CMV-GF) is a heat-stable, acid-labile polypeptide that is sensitive to trypsin and dithiothreitol. CMV-GF is an early product of the infected cells and defective virions are primarily responsible for its induction. Microtubule depolymerization is necessary for the induction of DNA synthesis by the CMV-GF, since taxol, an inhibitor of microtubule depolymerization, blocks its effect.

Relative IgG titres to specific viral proteins in acute and convalescent sera from patients with primary and recurrent genital herpes simplex virus type 2 (HSV-2) infections were determined using an immunoblot assay. Patients with recurrent genital infections generally had high titres of antibody reactive with two of the three major viral glycoproteins (gD and gG) as well as with several viral capsid proteins in both acute and convalescent sera. In contrast, patients experiencing primary genital HSV-2 infections exhibited marked differences in the polypeptide reactivity profiles of acute and convalescent sera. Of particular interest was the observation that the earliest and strongest antibody response was directed not against the viral glycoproteins but rather to an internal capsid protein(s) of HSV-2.

Borna disease virus has been adapted to the mouse, which required at least three passages in rat brains. Genetic specificity as studied with five inbred mouse strains was not evident. Newborn mice inoculated intracerebrally expressed antigen in neurons and remained persistently infected, with up to 107 infectious units per gram of brain tissue. Animals infected at different ages developed no disease and had high titres of antibodies.

The stock culture of solanum nodiflorum mottle virus (SNMV) was freed from RNA-2 by passage through single lesions induced in inoculated leaves of Nicotiana debneyi by dilute inocula of partially purified SNMV RNA-1. This isolate (S1) was indistinguishable serologically and in symptomatology from the stock culture of SNMV. Using a sensitive bioassay for detecting RNA-2, no SNMV RNA-2 was found in RNA from particles of the S1 isolate purified after three successive passages in Nicotiana clevelandii. Addition of SNMV RNA-2 (which is not infective alone) had little or no effect on the infectivity of S1 RNA but restored the RNA content of particles to that found in the stock culture (RNA-1 and RNA-2). However, S1 did not support the replication of the RNA-2 from lucerne transient streak virus (LTSV). The possible interaction of the RNA-2 species from LTSV and SNMV with the genomes of other plant viruses was tested by mixing the RNA-2 species with nucleic acid from 11 other viruses. The survival of RNA-2 activity on inoculated leaves for up to 15 days complicated the interpretation of the results of these tests but a small amount of LTSV RNA-2 and SNMV RNA-2 was obtained only from particles of turnip rosette virus purified from plants inoculated with the relevant RNA mixtures. These and other data suggest that these RNA-2 molecules with physicochemical properties similar to viroids found in particles of some sobemoviruses are satellite RNA species whose multiplication is assisted by some, but not all, of the viruses in this group.