Density difference of DNA of human herpes simplex viruses, types I and II

Similarities and Differences in the Development of Laboratory Strains and Freshly Isolated Strains of Herpes Simplex Virus in HEp-2 Cells: Electron Microscopy

HEp-2 cells infected with two laboratory strains (mP and MP) and two freshly isolated strains (F and G) of herpes simplex virus were fixed at intervals between 4 and 50 hr postinfection and sectioned, and were then examined with the electron microscope. These studies revealed the following. (i) All four strains caused identical segregation of nucleoli and aggregation of host chromosomes at the nuclear membrane. (ii) The development of MP virus could not be differentiated from that of its parent mP strain. (iii) There were quantitative differences between laboratory (mP) and freshly isolated (F) type 1 strains. Thus, cells infected with F contained numerous nuclear crystals of nucleocapsids and relatively few cytoplasmic structures containing enveloped nucleocapsids. Conversely, cells infected with mP or with MP virus contained numerous cytoplasmic structures with enveloped nucleocapsids and relatively few nuclear crystals of nucleocapsids. (iv) There were qualitative differences between type 2 strain (G) isolated from genital lesions and type 1 strains. Thus, cells infected with the G strain contain numerous filaments in nuclei and unenveloped and partially enveloped nucleocapsids in the cytoplasm. Of particular interest is the finding that cytoplasmic membranes in apposition to nucleocapsids were thickened and bent as if they were enveloping the particle. The significance of the qualitative differences in the development of the four strains is discussed.

Tetrahydrouridine specifically facilitates deoxycytidine incorporation into herpes simplex virus DNA

As reported by Jamieson and Subak-Sharpe (J. Gen. Virol. 31:303-313, 1976), exogenous deoxycytidine is very poorly incorporated into herpes simplex virus DNA. Here it is shown that this incorporation was dramatically increased in the presence of tetrahydrouridine (THU), a specific inhibitor of cytidine-deoxycytidine deaminase. Thus, the exclusion of deoxycytidine from herpes simplex virus DNA probably results from massive degradation by the deaminase, which is consistent with the observation that in the absence of THU, most of the nucleotides formed from exogenous deoxycytidine are dUMP. The effect of tHU upon deoxycytidine incorporation was specific for herpes simplex virus-infected cells; THU did not increase deoxycytidine incorporation into DNA of uninfected cells. Therefore, one might expect THU to enhance the antiviral activity of 1-beta-D-arabinofuranasylcytosine since this analog is also readily deaminated. However, THU increased both the antiviral activity and the cell toxicity only slightly and to about the same extent. Therefore, the metabolism of 1-beta-D-arabnofuranosylcytosine is different from that of deoxycytidine in herpes simplex virus-infected cells.

Immunological reactivity of herpes simplex virus 1 and 2 polypeptides electrophoretically separated and transferred to diazobenzyloxymethyl paper

In this paper we report that viral polypeptides from herpes simplex virus 1 (HSV-1) and 2 (HSV-2)-infected cells electrophoretically separated in sodium dodecyl sulfate-polyacrylamide-agarose gels and transferred to diazobenzyloxymethyl paper can react with rabbit hyperimmune sera, both polyvalent and prepared against specific antigens. The polyvalent hyperimmune sera against HSV-1 reacted with 17 HSV-1 polypeptide bands and 8 HSV-2 polypeptide bands. Concordantly, polyvalent sera against HSV-2 reacted with at least 16 HSV-2 polypeptide bands and 8 HSV-1 polypeptide bands. The antisera prepared against the specific antigens reacted with a smaller number of polypeptide bands. Preimmune sera and immune sera did not react with electrophoretically separated polypeptides from infected and uninfected cells, respectively. The immune localization of separated antigens test provides a powerful technique for identification of immunogenic viral polypeptides, especially those which are normally insoluble and therefore unavailable for immunological reactivity in immune precipitation tests.

Herpetic whitlow

Three patients with herpetic whitlow are presented. Virus typing revealed herpes simplex virus type 1 in two and type 2 in one of the cases. There is a high risk of infection among medical personnel.

Use of biological characteristics to type Herpesvirus hominis types 1 and 2 in diagnostic laboratories

Fifty clinical isolates of Herpesvirus hominis were typed by pock size on chicken embryo chorioallantoic membranes, sensitivity to heparin, and plaque formation on chicken embryo cell cultures. Of 19 isolates that were typed serologically, there was 100% concordance with respect to plaque formation. Pock size was incorrect in one instance and indeterminate in another. Heparin sensitivity was incorrect for one. Of 31 strains that were only biologically characterized, there were four for which heparin sensitivity did not agree with the other two characteristics. Of the three biological tests, the ability to form plaques in chick cell monolayer was the most reliable indicator type.

Incidence of Herpesvirus hominis antibodies among blood donor populations

The microneutralization test was used to determine the occurrence of antibodies to Herpesvirus hominis Type 1 and Type 2 in sera from patients attending the Special Clinic, Bristol Royal Infirmary, with proven herpes genitalis, and in sera taken from blood donors in Bath, Dursley, and Bristol, as well as from donors in three different prison populations. The findings in patients with herpes genitalis indicate that the test accurately reflects the antibody response expected in relation to the type of herpes virus isolated from the lesions. The incidence of Type 2 antibodies among the blood donors ranged from 5 per cent. for donors from the Bath area up to 60 per cent. among donors from Dartmoor prison. The findings suggested that Type 2 herpes infection could spread among longterm prison populations, and it is postulated that this may be due to both homosexual contact, and also by non-sexual contact, either directly or via fomites.

Identification of strains of herpes simplex virus by comparison of the density of their DNA using the preparative ultracentrifuge

The buoyant densities of the DNA of herpes simplex virus type 1, type 2 and Pseudorabies virus, as determined in the analytical ultracentrifuge, are 1.725, 1.727 and 1.731 correlating with G+C contents of 67, 69 and 73 per cent respectively. The density differences for the DNA's of type 1 and type 2 herpes simplex viruses have been confirmed in experiments with isotopically labelled DNA from four type 1 and six type 2 strains by preparative CsCl gradient ultracentrifugation. The DNA of all the type 2 strains was denser than that of any of the type 1 strains examined. Despite these differences in DNA base composition of type 1 and type 2 strains, nearest neighbour analysis of their DNA's disclosed no obvious differences in doublet pattern or general design.

Rapid typing of herpes simplex virus strains using the indirect immunoperoxidase method

The indirect immunoperoxidase technique with type-specific antisera was compared to kinetic neutralization for the typing of herpes simplex virus strains. There was complete agreement between the results obtained by kinetic neutralization and indirect immunoperoxidase. The indirect immunoperoxidase assay was far simpler to perform and interpret than the kinetic neutralization tests, and it offered a rapid means for the routine antigenic typing of herpes simplex isolates.

Growth of murine cytomegalovirus in a heterologous cell system and its enhancement by 5-iodo-2'-deoxyuridine

Mouse cytomegalovirus replicated in rabbit kidney cultures, a cell system of nonrodent origin. However, the sensitivity of these cultures, and the yields of virus therefrom, were lower than those of mouse cultures. Although a cytopathic effect developed in rabbit kidney cultures inoculated with sufficient amounts of the virus, such cultures were unsatisfactory for plaque assay. This was also true when rabbit fibroblast cultures were used, even though the murine cytomegalovirus replicated much better in mouse fibroblasts than in mouse kidney cultures, the latter of which contained extensive areas of epithelial cells. Viral growth in rabbit kidney cells was considerably enhanced when those cells had been initiated and grown in the presence of 5-iodo-2'-deoxyuridine; not only were the viral titers increased, but also the clarity and distinctness of the inclusion bodies.

Equine herpesviruses: antigenic relationships and deoxyribonucleic acid densities

Equine herpesviruses with a deoxyribonucleic acid density of 1.716 to 1.717 g/cm(3) were compared with one another by the plaque-reduction test and by the rate of development of cytopathic effect as indicated by plaque size in rabbit kidney cultures. Of the 19 isolates studied, the 9 which had already been tentatively labeled equine abortion viruses were serologically similar to one another; each of them grew more quickly than did any of the other 10 isolates although the mean plaque sizes formed a series of gradations with no clear hiatus which would permit the unequivocal delineation of the abortion viruses from the slowly growing strains. The 10 slowly growing isolates showed antigenic heterogeneity even though complement was present; the neutralizing capacity of an antiserum against the heterologous strains was, in most instances, markedly less than against the homologous strains, the range of the 50% endpoints being much greater than that observed among the equine abortion viruses, or among isolates of herpes simplex type 1. There was no cross neutralization between the equine abortion viruses and any of the 10 slowly growing isolates. An extra band of deoxyribonucleic acid, at 1.723 to 1.725 g/cm(3), was present in two of the slowly growing strains when originally grown in rabbit cells, but was no longer present after passage in cat cells. This band occupied the same position as one reported in the hamster-passaged strain of equine abortion virus, and had a density similar to that of the equine genital herpesvirus. Although the taxonomic demarcation of the equine abortion viruses and the slowly growing herpesviruses from one another is still open to question, they can be conveniently labeled equine herpesviruses 1 and 2, respectively; the genital virus would be termed equine herpesvirus 3.

Genetic relatedness of type 1 and type 2 herpes simplex viruses

The extent of homology between herpes simplex virus(1) and(2) (HSV-1 and HSV-2) deoxyribonucleic acid (DNA) was measured in two ways: (i) by determination of the relative rate of hybridization of labeled HSV-1 and HSV-2 DNA to excess unlabeled HSV-1 or HSV-2 DNA immobilized on filters and (ii) by determination of the rate of hybridization of labeled HSV-1 and HSV-2 DNA to excess unlabeled HSV-1 or HSV-2 DNA in solution. Approximately 40% of HSV-1 and HSV-2 DNA is homologous at hybridization temperatures 25 C below the melting temperature (T(m)) of HSV DNA (liquid-filter annealing). Lowering the temperature to 34 C below the T(m) increased the extent of homology to 46% (liquid annealing). The extent of base-pairing in HSV-1-HSV-2 heteroduplex DNA was determined by thermal chromatography on hydroxyapatite. Heteroduplexes of HSV-1 and HSV-2 DNA eluted in a single peak whose midpoint (Te(50)) was 10 C below that of the homoduplex. Conspicuously absent were heteroduplexes that eluted at more than 15 C below the Te(50) of the homoduplex. The data indicate the existence of a variable region of DNA (54%) with very little, if any, homology and an invariable region (46%) with relatively good (85%) matching of base pairs.

Efficiency of plating on chick embryo cells and kinetic neutralization of Herpesvirus hominis strains

Since it appeared that plaque formation in monolayers of primary chick embryo cells might provide a simple technique for the typing of Herpesvirus hominis strains, 100 isolates were tested for their efficiency of plating (EOP) on chick embryo cells versus plating on human embryonic fibroblasts. EOP values varied from 10(0) to 10(-6): 88% of the strains of genital origin had an EOP equal to or greater than 10(-2), and 82% of the oral isolates had an EOP equal to or less than 10(-3). Kinetic neutralizations were done with 53 strains, including those 12 with an EOP of 10(-2) or 10(-3). An estimate of antigenic relatedness (R(a)) between strains was calculated from the neutralization results. Although the site of recovery, EOP, and R(a) generally correlated, the EOP of some oral strains did not agree with the neutralization results, and some genital strains showed type 1 EOP and R(a) values. Selection of variants with increased EOP values did not result in accompanying changes in R(a). Thus, the two markers appeared to vary independently. These data support other findings which suggest that there may be no absolute correlation between biological and antigenic markers in herpesviruses and that a larger number with more diversity of strains should be examined for more markers before a typing system is established.

Concentrations of idoxuridine in serum, urine, and cerebrospinal fluid of patients with suspected diagnoses of Herpesvirus hominis encephalitis

A reproducible microbiologic assay of microgram quantities of idoxuridine (IDU) in serum, urine, or cerebrospinal fluid is presented. The antiviral assay is not interfered with by type-specific antibody or interferon. During slow intravenous infusions of idox-uridine (4 mg/min) in patients with suspected diagnoses of Herpesvirus hominis encephalitis, the rate of inactivation and/or removal of drug exceeded its administration. During several rapid infusions of idoxuridine (50 mg/min) significant quantities of the drug were found in serum, urine, and cerebrospinal fluid. Idoxuridine is not significantly bound to serum proteins and is not deiodinated in fresh serum or urine in vitro to inactive products (iodouracil, uracil, iodide). It is rapidly excreted into the urine. Inactivation of IDU occurs in tissues. This antiviral assay of IDU in body fluids should be applicable to other viruses and potential antiviral agents. Minimal inhibitory concentrations of IDU for fresh isolates of Herpesvirus hominis (type 1 or 2) were determined. Type 1 herpesviruses' microplaques in baby hamster kidney cell (BHK 21) tissue cultures were sensitive to 2.5-10 mug/0.4 ml. Type 2 macroplaques required 25-50 mug/0.4 ml. This latter characteristic may be an additional biologic marker which may be useful in suggesting type-specificity of herpesvirus isolates.

Size, composition, and structure of the deoxyribonucleic acid of herpes simplex virus subtypes 1 and 2

Studies of the size, composition, and structure of the deoxyribonucleic acid (DNA) of the F and G prototypes of herpes simplex virus (HSV) subtypes 1 and 2 (HSV-1 and HSV-2) showed the following. (i) As previously reported by Good-heart et al. HSV-1 and HSV-2 DNA have a buoyant density of 1.726 and 1.728 g/cm(3), corresponding to 67 and 69 guanine +/- cytosine moles per cent, respectively. The difference in guanine plus cytosine content of the DNA species was confirmed by the finding of a 1 C difference in T(m). (ii) The DNA from purified virus on cocentrifugation with T4 DNA in neutral sucrose density gradients sedimented at 55S, corresponding to 99 +/- 5 million daltons in molecular weight. HSV-1 and HSV-2 DNA could not be differentiated with respect to size. (iii) Cosedimentation of alkali-denatured DNA from purified virus with T4 DNA on alkaline sucrose density gradients consistently yielded several bands of single-stranded HSV DNA ranging from fragments 7 x 10(6) daltons to intact strands 48 x 10(6) daltons in molecular weight.

Biological characteristics of cloned populations of herpes simplex virus types 1 and 2

By using cloned types 1 and 2 herpes simplex virus, obtained by selecting large and small plaques produced by material from human lesions, studies were performed to compare properties between preparations of each type. Regarding the rate of inactivation by ultraviolet light, no differences were found between the two antigenic types and none between the preparations obtained from either type. In contrast, type 1 preparations were found to be more readily inactivated at 45 C than type 2. Plaque size of cloned preparations changed by passage in cell culture. A broader range of plaque sizes was obtained, and average plaque size was larger. After 20 passages, preparations obtained from different types gave rise to one of three kinds of cytopathic effect. The cytopathic effect produced by type 1 preparations remained as before 20 passages and consisted of round cells in a compact central mass. For type 2, two kinds of cytopathic effect were seen in cloned preparations. This consisted of aggregates of round cells (seen in preparations before 20 passages) or of large, loose aggregates of round cells of various sizes. Results from neutralization studies using virus before and after 20 passages in cell culture versus antisera prepared against live or ultraviolet-inactivated virus showed no differences between cloned preparations obtained from a given type.

Type 1 and type 2 herpes simplex viruses: serological and biological differences

Forty isolates of herpes simplex virus were compared by means of cross-neutralization curves. The 11 oral isolates were serotype 1, and all 29 genital/anal isolates were serotype 2. The cytopathic effects of the two serotypes were consistently different. Passage of strains of type 1 and type 2 in mice and in rabbits yielded two variants, although the majority of the strains remained unchanged serologically and in their cytopathic effects. The two variants were derived from type 1 strains and differed from the parent strains in their cytopathic effects, each of them producing syncytia and enlarged plaques. They had, however, retained the serotypic properties and the deoxyribonucleic acid (DNA) densities of their parent strains. The Roizman syncytial/macroplaque strain of herpes simplex virus was also included in the study; the density of its DNA (1.727 g/ml) was typical of type 1 strains, and serologically it seemed to be basically a type 1 strain, although it was neutralized by type 2 antiserum slightly better than were other type 1 strains. Growth curves were performed of the two serotypes in rabbit kidney, human fibroblast, and mouse embryo tissue cultures. The type 2 strains attained lower titers of infectivity in these three cell systems; the levels of infectivity of type 2 virus in the culture fluid decreased much more rapidly after the maximum had been attained than did the levels of infectivity of the type 1 strains, due to the greater instability of the type 2 virus. Parallel titrations of different strains in tissue cultures and intracerebrally in mice indicated that the latter assay system was usually more sensitive for type 2 strains than it was for type 1 strains. The paralytic sequelae and inflammatory changes of lumbar ganglia and spinal cord in young rabbits inoculated extraneurally with strains of the two serotypes also indicate that the type 2 virus is more virulent in laboratory animals than is type 1 virus.

Herpes simplex virus: dry mass

Dry mass of herpes simplex virus particles was measured by quantitative electron microscopy after isolation by surface spreading and critical-point drying of infected cells. The core weighed about 2 x 10(-16) gram, the empty naked capsid 5 x 10(-16) gram, the full naked capsid 7 x 10(-16) gram, and the enveloped nucleocapsid 13 x 10(-16) gram.

Filamentous structures of type 2 Herpesvirus hominis infection of the chorioallantoic membrane

In view of recent recognition of the existence of two Herpesvirus hominis (HVH) types with antigenic and biological differences, an electron microscopic study was undertaken of pocks produced on the choriallantoic membrane of embryonated eggs after infection with type 1 and type 2 HVH strains. Besides the typical morphological features of herpesvirus infection noted by several investigators, it was observed that type 2 HVH also produced microtubules measuring approximately 19 nm in both nucleus and cytoplasm. Although the nature of these filamentous structures is still unclear, consideration is given in this paper to the possibility that they may represent viral structural subunits, aberrant forms or neoantigens.