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Biomedical subjects

S B Halstead

Publications and source records attributed to S B Halstead.

At least 91 records · Page 5Linked to original sources
PubMed1978

Phytohemagglutinin enhancement of dengue-2 virus replication in nonimmune rhesus monkey peripheral blood leukocytes.

Phytohemagglutinin treatment of peripheral blood leukocytes from dengue nonimmune monkeys enhanced dengue-2 virus replication. Enhancement was due primarily to an increase in the number of infected cells. Destruction of mononuclear phagocytes with silica did not significantly inhibit virus replication in phytohemagglutinin-treated cultures. Pokeweed mitogen, concanavalin A, and streptolysin O stimulated increased deoxyribonucleic acid synthesis in monkey leukocytes but did not enhance virus replication. None of the mitogens significantly affected virus replication in cultures of dengue-immune monkey peripheral blood leukocytes.

Animals↗
PubMed1978

Ultrastructural studies on dengue virus infection of human lymphoblasts.

Ultrastructural studies of dengue-2 virus-infected lymphoblastoid Raji cells showed that the virus induced an increase in the size of the rough endoplasmic reticula (RER) and that the replication of the virus was confined to the cisternae of these RER. The proliferating RER formed cytoplasmic inclusions that could be seen by light microscopy. This observation could be used as evidence of a cytopathogenic effect of dengue virus on infected Rajii cells in routine cultures. Accumulation of virions in the infected cells was minimal in comparison with other cell systems, however. Sporadic clusters of mature virions were often seen on the plasma membrane. These extracellular virions were distributed adjacent to the virus-bearing RER and were presumably released virions. Vertical transmission of the virus was evident in mitotic lymphoblasts. The replication pattern of dengue virus in lymphoblastoid cells suggests that efforts should be made to determine whether blast-transformed lymphocytes, numerous in secondary dengue infections, support dengue virus replication in vivo.

Cell Line↗
PubMed1977

Dengue viruses and mononuclear phagocytes. I. Infection enhancement by non-neutralizing antibody.

Cultured mononuclear peripheral blood leukocytes (PBL) from nonimmune human beings and monkeys are nonpermissive to dengue 2 virus (D2V) infection at multiplicities of infection of 0.001-0.1, but become permissive when non-neutralizing dengue antibody is added to medium. D2V infection occurred in PBL prepared from anti-coagulated but not from defibrinated plasma. Infection enhancement was produced by multiple lots of heterotypic anti-dengue raised in several mammalian species. Homotypic anti-dengue neutralized D2V at high concentrations but enhanced at low concentrations; enhancement end point in one serum was 1:320,000. The infection-enhancing factor was a noncytophilic antibody of the IgG class. D2V infection occurred in the absence of heat-labile complement components but did not occur when complexes were prepared with anti- dengue F(ab)(2). Treatment of PBL with several proteases increased permissiveness to D2V infection by immune complexes but not by virus alone. Two rhesus monkey serums collected 14 days after D2V infection contained an IgG antibody with high-titered enhancing activity but with no hemagglutination-inhibition or neutralizing activity. Virus-antibody complexes are irreversibly attached to PBL within 15 min and completely internalized in 60 min. There was considerable variation in cellular infection in different experiments, however, maximum virus yields usually exceeded 1,000 plaque-forming units per 1 x 10(6) PBL occurring between 2 and 4 days in culture. In vitro antibody-dependent infection of PBL provides a possible model for study of pathogenetic mechanisms in infants with dengue shock syndrome who passively acquire maternal anti-dengue IgG.

Animals↗
PubMed1977

Dengue viruses and mononuclear phagocytes. II. Identity of blood and tissue leukocytes supporting in vitro infection.

Studies were made on the identity of human and monkey mononuclear leukocytes permissive to antibody-enhanced dengue 2 virus (D2V) infection. In cultures of peripheral blood leukocytes (PBL) inoculated immediately after separation, it was concluded that only mononuclear phagocytes support dengue infection. This is based upon observations that D2V-permissive cells were resistant to 1,200 rads, were both plastic adherent and nonadherent, were removed when passed through nylon wool columns in 10 percent fetal bovine serum or 100 percent autologous serum, and were destroyed by incubation with 100 mug/ml particulate silica. On direct immunofluorescence staining, perinuclear dengue antigen was visualized at 24 h, becoming maximal at 60 h. Antigen-containing cells had ample cytoplasm, ruffled cytoplasmic membrane, and 73 percent were actively phagocytic. As further evidence of the infection of mononuclear phagocytes, antibody-enhanced D2V replication was observed in bone marrow cultures from five of five rhesus monkeys, but not in cell cultures of spleen, thymus, or lymph nodes prepared from the same animals. It is hypothesized that dengue virus complexed with non-neutralizing antibody is internalized by immune phagocytosis in a mononuclear phagocyte with a defective virus-destroying mechanism. Dengue permissiveness may depend upon cellular immaturity since bone marrow leukocytes could be infected even when held for 4 days before infection while PBL held for this time decreased in permissiveness. In vitro antibody-dependent infection of mononuclear phagocytes should prove useful as a model for study of immunopathologic mechanisms in human dengue.

Animals↗
PubMed1977

Infections with two dengue viruses in Greece in the 20th century. Did dengue hemorrhagic fever occur in the 1928 epidemic?

From contemporary clinical accounts we hypothesized that the 1928 dengue epidemic in Greece may have been an earlier occurrence of dengue hemorrhagic fiver/dengue shock syndrome (DHF/DSS). To study the possibility that two different dengue viruses may have been involved, serums from 62 Athenians alive during the epidemic were examined for dengue antibodies; 73 per cent showed evidence of prior dengue infection. Monotypic neutralizing antibodies were found to two different dengue viruses, types 1 and 2. A large proportion of the sampled population had evidence of two or more past dengue infections. Since there is no evidence that dengue viruses have been transmitted in Greece since 1928, during the epidemic a very large number of persons immune to one dengue type must have acquired infections with a secon type. The virological criteria for secondary infection DHF/DSS are thus satisfied. Although DHF/DSS is currently restricted to Asia and the Pacific, the Greek oubreak suggests a biological potential for fatal consequences of dengue infections in Caucasians, particularly the elderly.

Adolescent↗
PubMed1976

Rubella immunization. Persistence of antibody four years after a large-scale field trial.

A long-term comparative field trial of three live, attenuated rubella vaccines (HPV-77 DE-5, HPV-77 DK-12, and Cendehill) was initiated in 1969 on the islands of Kauai and Hawaii in the state of Hawaii. Rubella hemagglutination-inhibition (HI) tests on prevaccination serum specimens from 7,931 children in the two study areas indicated an overall susceptibility to rubella of nearly 70%. The rates of seroconversion of 5,153 seronegative subjects to HPV-77 DE-5, HPV-77 DK-12, and Cendehill vaccine were 97.5%, 99.9%, and 99.8%, respectively. Over the subsequent four-year follow-up period, during which time natural exposure to rubella was minimal, the percent decline of geometric mean titers did not vary substantially among the three vaccine groups and measured about twofold for all three. A total of only 28 vaccines (0.7%) who seroconverted to one of the vaccines in 1969 lost all measurable antibody by 1974. Measurable antibody persisted in more than 98% of all vaccinees over the four-year period. Reinfection, thought possibly to be an important factor in maintaining titers, did not occur frequently in the study population and could not be related to outbreaks of disease.

Age Factors↗
PubMed1976

Booster vaccination with further live attenuated measles vaccine.

Revaccination with live attenuated measles vaccine was evaluated in a large group of children to determine (1) if protective antibody to measles infection could be augmented and (2) after what interval will the revaccination yield optimal results. The rate of decline in measles hemagglutination-inhibition (HI) antibody was observed to be directly related to the time interval since the previous vaccination, and individuals with declining titers became increasingly responsive to revaccination with a maximal response approximately four to six years after previous vaccination. Six-month follow-up studies demonstrated sustained elevations in measles HI antibody titers. Measles-neutralizing antibody showed less tendency to sustain a titer increase with revaccination. The observations suggest that revaccination with live, further attenuated measles vaccine is safe and may augment immunity.

Adolescent↗
PubMed1976

Serologic response to revaccination with two rubella vaccines.

Three years after receiving rubella vaccine, 1,060 elementary school children living on the island of Maui, Hawaii, were revaccinated with either HPV-77 DE-5 or RA 27/3 rubella vaccine given subcutaneously or intranasally in order to compare the effectiveness of these two vaccines in raising antibody titers. RA 27/3 was the more effective booster vaccine, producing fourfold or greater titer rises in 20.1% of recipients, including 80% of children with hemagglutination-inhibiting antibody titers less than or equal to 1:40 at the time of revaccination, intranasal revaccination was not significantly more effective than subcutaneous revaccination, although it did elicit higher titers in children who responded. Responses differed according to the vaccine that children had received three years earlier. Because antibody titers have persisted in vaccinated children, routine administration of a second dose of rubella vaccine is not currently recommended.

Administration, Intranasal↗
PubMed1976

Replication of dengue viruses in cultures of peripheral blood leukocytes from dengue-immune rhesus monkeys.

Dengue virus of types 1, 2, and 4 replicated reproducibly in cultures of peripheral blood leukocytes from 18 dengue-immune rhesus monkeys but failed to multiple in peripheral blood leukocytes from 25 nonimmune monkeys. Replication was observed at input multiplicity of infection of 0.1 and 0.01 but irregularly at less than or equal to 0.001. Dengue viruses in permissive leukocytes achieved maximal titers on days 2-4 of culture. Viral replication in peripheral blood leukocytes from animals immune to a different type of dengue virus and in animals immune to two or more types of dengue virus was quantitatively similar to that in peripheral blood leukocytes from homotypically immune donors. Dengue virus permissiveness developed between two and three weeks after primary dengue infections. Leukocytes of animals that developed immunity to dengue virus remained permissive to in vitro infection by dengue virus of types 1 and 2 for prolonged periods, but within six months permissiveness to type 4 decreased. Thus an immunological dependence of in vitro dengue virus replication in simian peripheral blood leukocytes was demonstrated.

Animals↗
PubMed1976

Dengue virus replication enhancement in peripheral blood leukocytes from immune human beings.

Dengue 2 virus replication in peripheral blood leukocyte cultures from 10 of 13 Asian or Polynesian subjects with actively acquired dengue immunity and two of three infants with passively acquired dengue antibody. Only 2 of 11 cultures from nonimmune infants or children supported viral replication. This study establishes a parallel in the biological behavior of human and simian PBL with respect to the immunological dependence of dengue virus replication in vitro. Elucidation of the mechanism (or mechamisms) regulating growth of dengue virus in leukocytes from immune hosts may contribute to an understanding of the role that virus-leukocyte interactions play in the pathogenesis of human dengue illness.

Adolescent↗
PubMed1975

Rubella vaccination: fertility control in a large-scale vaccination program for postpubertal women.

Despite nationwide immunization programs, rubella infections during pregnancy continue. To solve this serious health problem direct immunization of women of reproductive age may be required. On a clinic basis, using nonphysician personnel, we vaccinated 404 susceptible women, ages 18 to 33; half were sexually active. Since pregnancy is proscribed for 2 to 3 months following rubella vaccination, a full range of family-planning services and a variety of contraceptive methods were used to ensure sustained fertility control. Sixteen vaccinees presented with possible conceptions in a 3 month follow-up. Of these, only five required treatment: two received diethylstilbestrol, two had menstrual inductions, and one an abortion. Administration of vaccine during a menstrual period was effective in preventing inadvertent vaccination of pregnant women. It was concluded that contraceptive counseling with adequate pregnancy termination backup makes it feasible to give rubella vaccine to highly motivated women.

Contraception↗
PubMed1975

A lipid inhibitor of dengue virus in human colostrum and milk; with a note on the absence of anti-dengue secretory antibody.

Neutralizing activity against dengue virus types 1--4 was observed in milk samples from 5 non-immune and 29 dengue immune women. Anti-dengue activity in milk and colostrum was found only in the lipid component. The inhibitory activity is directed against the virus and not cell surfaces. When immunoglobulin types IgM,IgA, IgG were isolated from colostrum from dengue immune women, no antibody activity was found. Anti-dengue activity in human milk did not decrease over a period of ten months after delivery.

Animals↗
PubMed1975

Dengue carrier culture and antigen production in human lymphoblastoid lines.

Replication of dengue type 2 (D2) viruses was studied in four lymphoblastoid cell lines; Raji, HR1, EB3 and RPMI 6410. The HR1 cell line failed to support D2 growth while the other cell lines showed varying susceptibility. Both D2 strain 16681 and strain New Guinea C (NGC) passaged in LLC-MK2 cells replicated readily in Raji cells, while a high mouse-brain-passaged NGC strain did not. A soluble complement-fixing (SCF) antigen from D2-infected Raji cells showed lines of identity with a D2SCF antigen prepared from infected suckling mouse brains. Electron microscopic studies of a D2 Raji carrier culture showed that virions were located in a membrane-vesicle complex in the cytoplasm of the cells. Precursors of viral particles were more frequently observed in the parts of the vesicle which had rough endoplasmic reticular membranes. Mature virus particles were observed often at the boundary of the other part of the vesicle, which consisted of smooth endoplasmic reticulum. Occasionally, a large crystalloid structure consisting of incomplete viral particles was seen in degenerative cells. Dengue carrier cultures in human lymphoblastoid lines may provide a convenient in vitro system for study of aspects of dengue virus-leukocyte interactions.

Antigens, Viral↗
PubMed1975

Dengue virus replication in cultures of peripheral blood leukocytes during the course of dengue haemorrhagic fever.

A preliminary study was made of the ability of cultured human peripheral blood leukocytes (PBL) to support dengue 2 infection. Leukocyte donors, children hospitalized with primary (one case) or secondary dengue infections (12 cases), were studied during the acute and convalescent stages of illness. D2 virus replication occurred infrequently in PBL cultures obtained from children before the 10th day after onset of symptoms (2/23 samples), but frequently thereafter (8/13 samples). The absence of virus permissive cells during the acute stage of illness might be explained by several different mechanisms, including the possibility that permissive PBL are exhausted as the result of a severe dengue infection. An unexpected finding was the appearance of dengue hemagglutination-inhibition antibodies in cultures of PBL obtained from children during the acute stage of secondary dengue infections.

Acute Disease↗
PubMed1974

Etiologies of the experimental dengues of Siler and Simmons.

Four participants in the American Army Philippine dengue (d) studies of Siler (1924-25) and five subjects from the studies of Simmons (1929-30) were bled 42 to 48 years after experimental infection. Sera were studied by hemagglutination-inhibition, complement-fixation and plaque reduction neutralization (PRNT) tests for antibodies to the known viral causes of the dengue syndrome in Asia and to St. Louis encephalitis virus. PRNT tests were done with and without fresh normal human serum (accessory factor). Serum from one of four Siler study volunteers had unequivocal evidence of only a previous d4 infection; the remainder had broadly reactive group B antibodies, including d4, suggesting past infection with two or more different dengue viruses. Sera from four of the Simmons study group had high-titered PRNT antibodies to d1 and the remaining serum had d1 antibody when accessory factor was added. In three sera there was monotypic PRNT antibody to d1. Acessory factor increased PRNT titers, particularly to d1 virus in the Simmons group. Only sera with antibody patterns suggesting past infections with two or more dengue viruses had high levels of SLE PRNT antibody. It is concluded that d4 was transmitted in the 1924 to 1925 and d1 in the 1929 to 1930 experiments. Notable differences in clinical features of dengue infections in the two studies suggest the possibility of the existence of an unique spectrum of responses to infection with different dengue virus type.

Adult↗
PubMed1974

Clinical and laboratory studies on haemorrhagic fever in Burma, 1970-72.

This three-year serologic study of 2 060 children with a clinical diagnosis of haemorrhagic fever, who were admitted to the Children's Hospital and other hospitals in Rangoon, has shown that the etiology of the illness was multiple. Of all these patients, 347 (16.8%) had a dengue infection (96 with primary and 251 with secondary dengue infections), 510 (24.7%) had chikungunya infections, 55 (2.7%) had simultaneous chikungunya and dengue, 263 (12.8%) had influenza A infections, 62 (3.0%) had influenza B, 12 (0.6%) had measles, and there were 811 (39.4%) for whom no etiology could be established. Epidemiological and clinical features and laboratory findings are discussed. Evidence is presented for human infections with all four types of denguevirus in Rangoon.

Child↗