Showing papers on "Dengue virus published in 1981"

Epidemic Dengue 3 in Central Java, Associated with Low Viremia in Man*

Abstract: An outbreak of dengue type 3 was studied in Central Java, Indonesia, in 1978. In contrast to previous dengue 3 epidemics in Central and East Java, this outbreak was less explosive, associated with mild illness, and low viremia. The dengue virus isolation rate from serologically confirmed patients was only 32% compared to 65% for an epidemic in Bantul a year earlier. Neither dengue hemagglutination-inhibition antibody titers nor day of illness on which specimens were collected accounted for this difference. These data suggest that some naturally occurring strains of dengue virus (endemic strains) are associated with low viremia and generally cause only mild illness in man.

Evidence for two mechanisms of dengue virus infection of adherent human monocytes: trypsin-sensitive virus receptors and trypsin-resistant immune complex receptors.

Abstract: Trypsin treatment of adherent human monocytes greatly reduced or eliminated the ability of these cells to support dengue virus replication. However, addition of dilute (nonneutralizing) antibody to the inoculum and the culture medium resulted in viral yields similar to those from monocytes not treated with trypsin. These results suggested that viral entry was facilitated by phagocytosis of immune complexes via Fc receptors on the monocytes. This concept was tested by (i) pretreating monocytes with aggregated gamma globulin, which resulted in a 40-fold reduction of viral yields after infection with dilute antibody-virus complexes and (ii) forming an immune complex with virus, antivirus F(ab')2 fragments, and rabbit anti-human Fab. Whereas F(ab')2 fragments alone would not enhance virus replication in trypsin-treated monocytes, the immune complex containing a rabbit Fc piece did increase the yield of dengue virus. These results suggest that dengue virus can infect a cultured monocyte in two ways: (i) through a viral receptor that is trypsin sensitive or (ii) through an Fc receptor that is not trypsin sensitive.

The use of Toxorhynchites mosquitoes to detect and propagate dengue and other arboviruses.

Abstract: Both sexes of Toxorhynchites amboinensis, an unusually large, non-blood sucking mosquito, were found to be as susceptible to infection with each of the four types of dengue virus by intrathoracic inoculation as Aedes albopictus. Tx. amboinensis infected with dengue virus could be identified easily by fluorescent antibody staining of head squashes and had advantages of size, hardiness, and safety (for females) as compared with Ae. albopictus. Tx. amboinensis also were more susceptible to infection with Japanese and St. Louis encephalitis viruses than were Vero cell cultures and appeared useful for detection and propagation of other flaviviruses and arthropod-borne viruses of other taxonomic groups.

Dengue-2 vaccine: virological, immunological, and clinical responses of six yellow fever-immune recipients.

Abstract: Six male volunteers, previously immunized with yellow fever vaccine, were inoculated subcutaneously with a live, attenuated dengue-2 virus (PR-159/S-1) candidate vaccine. Five recipients developed viremia 8 or 9 days after vaccination, which lasted 1 to 10 days. The onset of viremia was followed by fever in three people, transient leukopenia in four, and an erythematous rash in one. One volunteer developed an oral temperature of 38.8 degrees C with headache, myalgia, fatigue, and photophobia suggestive of mild dengue fever. All five viremic volunteers developed fourfold or greater rises in serum neutralizing antibody. The sixth volunteer, who had a low titer of preexisting dengue-2 neutralizing antibody, had no viremia, no symptoms, and a modest rise in hemagglutination inhibiting antibody. Virus isolates obtained from plasma retained the small-plaque and temperature-sensitive growth characteristics of the vaccine virus in vitro. In this study, the vaccine virus genetically stable and immunogenic and seemed sufficiently attenuated for additional testing in humans.

Infection of young adult mice with dengue virus type 2

Abstract: Young adult female mice, five to six weeks old, were injected intraperitoneally with 2·5 × 106·3 LD50 of dengue-2 virus, New Guinea C strain. The mice were killed on day 1, 2, 3, 4, 5, 6, 7, 10, 14, 21, 28 and 35 respectively. By means of the immunofluorescent antibody technique, viral antigen appeared as irregular granules in the reticuloendothelial cells of liver, lymph nodes and spleen of infected mice on the first day after inoculation and then diminished. From the fifth to sixth day of infection dengue antigen appeared again as homogeneous staining in the cytoplasm of single or groups of mononuclear cells in the lymphatic sinuses only. Later, by the third week of infection, dengue antigen could be seen in the mononuclear cells located in the marginal zone of lymphoid follicle of the spleen, the pattern of staining changing to bright spherical granules. At the same time, the deposition of immune complexes (composed of dengue antigen, mouse gamma and β1C globulin) could be seen in the renal glomeruli of infected mice. Serum antibody to dengue virus was found at low levels, being maximal on the 14th day after infection. Dengue virus was not isolated from the sera or from the infected organs. Granulomatous inflammation developed in lymph nodes and liver of mice infected with dengue virus and in mice inoculated with normal mouse brain suspension. Proliferative glomerular lesion was observed on day 14 after inoculation without definite abnormal urine findings.

Dengue in the Seychelles

Abstract: Epidemics of dengue-like illness occurred in the Seychelles from December 1976 to April 1977 and from December 1978 to January 1979. Dengue 2 virus was isolated from individuals who had been in the Seychelles in 1977. From February to April 1979, sera were collected from outpatients in Mahe, Seychelles, who had not previously been hospitalized with a dengue-like illness. Results of neutralization tests with these sera indicated that prevalence rates for the four dengue viruses were between 81% and 91.8% and that dengue 2 was the most probable etiological agent in the epidemics. In addition, antibodies to chikungunya (8.7%) and Sindbis (7.4%) viruses were found, providing, for the first time, evidence of the presence of these two alphaviruses in the Seychelles.

Thymus-dependent lymphocytes of dengue virus-infected mice spleens mediate suppression through prostaglandin.

Abstract: Our earlier observations indicate that adoptive transfer of spleen cells obtained from dengue type 2 virus (DV)-primed mice suppressed DV antigen-specific antibody secretion as detected by Jerne PFC technique. Findings of this paper indicate that the suppression was produced by non-glass-adherent cells, macrophage-depleted (by carbonyl iron) cells and by T lymphocytes of the spleen but not by the glass-adherent cells and B lymphocytes. The activity of these cells is dependent upon production of prostaglandin as shown by abrogation of their suppressor activity by pre-treatment of cells by indomethacin or aspirin which are known to block synthesis of prostaglandins.

Geographic Aedes aegypti strains and dengue-2 virus: Susceptibility, ability to transmit to vertebrate and transovarial transmission

Abstract: Summary Relations between dengue-2 virus (New Guinea C strain) and its most common vector, Aedes aegypti , were investigated in 5 geographical strains of mosquitoes originating from endemic areas for dengue fever. Four strains were recently collected from regions with high (Hanoi strain, Vietnam), rather high (Guadeloupe strain, Carribean), low (Lagos strain, Nigeria), or no incidence for dengue virus (Kari strain, Upper Volta). The fifth strain was colonized in the laboratory for several years (Queensland strain, Australia). Following infection by intrathoracic inoculation, the susceptibility of the strains to dengue-2 virus, their ability to transmit the virus to suckling mice (SM) by bite and the possibility of transovarial transmission were compared. The virus replicated in the 5 strains at the same rate averaging 4.1 log 10 PFU/mosquito, and the 50% mosquito infection dose was similar for each strain (0.001 PFU). The ability of infected females to transmit the virus to SM by bites varied from 37 to 56% according to the strain. Transovarial transmission was demonstrated in 4 strains. The Kari strain from non-endemic region did not transmit the virus. The minimal filial infection rate was rather low ranging from 0.3 to 1.2‰ Infected progeny of both sexes were detected only in the first or second ovarian cycle from eggs ovoposited between the 14th and the 16th day post inoculation of parent females.

Suppression of dengue virus replication in vitro by rimantadine hydrochloride.

Abstract: The effects of rimantadine on dengue virus replication were examined in a variety of tissue culture systems. The growth of dengue virus type 2 in human peripheral blood leukocytes (PBL) was completely suppressed when rimantadine was included in the culture medium at a concentration of 25 microgram/ml. Similarly, rimantadine caused a significant inhibition of dengue virus replicaton in cultures of rhesus monkey PBL. Addition of drug into virus-infected LLC-MK2 cell cultures caused a decrease in the production of all four types of dengue virus. Maximal inhibition of dengue virus replication by rimantadine was observed when the drug was added immediately following the viral adsorption period. Rimantadine did not induce may cytopathic effects on either LLC-MK2 cells or PBL at concentrations less than 75 microgram/ml. These findings demonstrate that rimantadine is an effective inhibitor of dengue virus replication in vitro, and indicate a need for further examination of the efficacy of rimantadine against severe dengue virus disease.

Dengue virus-induced cytotoxic factor suppresses immune response of mice to sheep erythrocytes.

Abstract: The present study was undertaken to investigate if the suppressed cell-mediated immune responses observed in dengue type 2 virus (DV)-infected mice could be due to the cytotoxic factor (CF) produced in the spleens of DV-infected mice. We have observed that CF given intravenously (i.v.) kills splenic cells and reduces the total cells in the spleen. Mice treated with CF have a significantly depressed immune response to sheep erythrocytes, viz. delayed-type-hypersensitivity as measured by footpad swelling reaction at 24 hr; Jerne's antibody plaque-forming cells in the spleen; and migration inhibition of spleen cells in presence of antigen. These findings are similar to those seen earlier in DV-infected mice.

Localization of Dengue Virus in Nude Mice

Abstract: Dengue virus (DV) is known to replicate in the brain tissue of mice when injected intracerebrally. However, other organs and tissues do not easily support the replication of DV. We have reported that a highly mouse-adapted strain of DV caused acute lethal infection in mice even when injected intraperitoneally (ip), and that host responses to DV infection, i.e., antibody production and mononuclear cell infiltration in the infected brain, were different in athymic nude (nul nu) mice and in their heterozygous littermates (nu/+) (6). Viral replication was detected not only in the brain but also in other organs and tissues of both kinds of mice. In this paper we present additional data, particularly on the morphological aspects such as localization of DV in the infected mice. DV type 1, Mochizuki strain (7), in the form of the supernatant of suckling mouse brain homogenates, was used. Four to six-week-old male Balbjc-nu/nu and nul+ mice were procured from Japan Clea Co., Ltd. Each mouse was inoculated ip with 107•0 to 107•8 plaque-forming units (PFU) of DV. At fixed times thereafter, each mouse was bled and the organs were removed. The organs were then divided into two or more portions, which were used for virus titration and histological examination, including hematoxylin-eosin (HE), periodic acid-Schiff (PAS), and indirect fluorescent antibody (FA) stains as well as electron microscopic (EM) observation. Figure I shows the growth curve and concentration of virus in the brain, skeletal muscle and heart of infected nu/nu mice. The virus was first clearly detected 4 days after infection, increased in amount and reached maximum titers at the time paralysis appeared. In the paralyzed mice, the highest virus titers were found in the brain (ca. 108 PFUIg), and the second highest in the skeletal muscle and heart (ca. 104 PFUIg). Our previous findings that the virus concentration in the heart of nu/nu mice was higher than in nul+ mice (6) were repeatedly confirmed. Lymph node, lung, liver, spleen and kidney also contained virus, although the titers varied from one sample to another. In our previous experiments it was not certain whether the virus content in the lymph node and spleen were of the same level or not, but the present studies clearly indicate that the infected lymph node had a higher concentration of virus than the spleen (Fig. 2).

In vitro virulence marker: growth of dengue-2 virus in human leukocyte suspension cultures.

Abstract: We wished to find a simple, biologically relevant method to evaluate the virulence of dengue viruses for human beings. Since cells of mononuclear phagocyte lineage may be important sites of dengue infection in primates, we evaluated the permissiveness of these cells to dengue virus as a correlate of virus virulence. Two wild-type, large-plaque, monkey-virulent dengue-2 virus strains and two small-plaque, monkey-avirulent dengue-2 virus strains were evaluated for their ability to replicate in human peripheral blood leukocyte cultures supplemented with enhancing antibody. One of the small-plaque strains was demonstrated to have reduced virulence for man. Wild-type dengue-2 viruses replicated readily in peripheral blood leukocyte suspension cultures, whereas small-plaque dengue-2 strains did not. Differences between our data and results obtained by other workers employing adherent peripheral blood leukocytes are discussed. Antibody-enhanced growth of dengue virus in suspension cultures of human peripheral blood leukocytes gives promise of being a simple in vitro system for characterizing dengue virus virulence.

[Characterization of the suppressor factor produced in the spleen of dengue virus-infected mice].

Abstract: The presence of a suppressor factor (SF) has been demonstrated in the homogenate of the spleen of dengue type 2 virus (DV)-infected mice which an adoptive intravenous (i. v.) transfer-suppressed DV-specific IgM-PFC in the spleen of recipient mice. The SF has been separated by prolonged agarose-gel electrophoresis from the DV-infected mice spleen homogenate. SF is highly potent, heat-labile, trypsin-resistant and unstable at acidic and alkaline pH. It is a low molecular wieght substance which is dialysable and is not sedimented on ultracentrifugation.

Quantitation of dengue precipitating antibody by inhibition countercurrent immunoelectrophoresis.

Abstract: The inhibition countercurrent immunoelectrophoresis test was employed to detect dengue virus antibody in patients' sera. Anti-dengue type 2 titers determined by inhibition countercurrent immunoelectrophoresis correlated well with hemagglutination inhibition titers. In secondary cases, more than fourfold increases in precipitating antibodies were observed. The control sera were negative except for sera from a few patients with systemic lupus erythematosus, which showed low titers. Simultaneous detection of dengue virus antigen and antibody in sera collected during the acute phase could confirm at least 90% of cases. This method is recommended as a routine technique to quantitate antibody in sera from suspected cases of dengue hemorrhagic fever.

Replication of dengue, yellow fever, St. Louis encephalitis and vesicular stomatitis viruses in a cell line (TRA-171) derived fromToxorhynchites amboinensis

Abstract: The replication of seven arboviruses in a cell line (TRA-171) derived from a nonhematophagous mosquito was studied. Four serotypes of laboratory adapted and three serotypes of unadapted dengue viruses replicated in the TRA-171 cell line, inducing syncytia. The sensitivity of TRA-171 cells to dengue virus infection was comparable to that ofAedes albopictus orA. pseudoscutellaris cells. Yellow fever, St. Louis encephalitis, and vesicular stomatitis viruses also replicated. All four serotypes of dengue viruses could be plaque assayed with TRA-171 cell cultures.

Lack of greater seroconversion of rhesus monkeys after subcutaneous inoculation of dengue type 2 live-virus vaccine combined with infection-enhancing antibodies.

Abstract: Four groups of six nonimmune male rhesus monkeys were inoculated subcutaneously with formulations of dengue type 2 vaccine virus DEN-2/S-1. Group A received 1.9 x 10(4) plaque-forming units of vaccine in normal human serum albumin diluent. Group B received the same dose combined with a dengue type 2-immune human serum diluted 1:1,600, beyond its neutralization endpoint of 1:300, but having an immune enhancement titer of 250,000. Groups C and D received 10-fold dilutions of these respective formulations. No migration-inhibitory factor was found when peripheral blood mononuclear leukocytes obtained on day 68 post-immunization from monkeys of all experimental groups were tested. No viremia was detected in any of the monkeys when sera taken on postvaccination days 1 through 12 were inoculated into adult Toxorhynchites amboinensis mosquitoes and LLC-MK2 cells. By day 89, four of the six monkeys had seroconverted by the neutralization test in each of groups A, B, and C, and three of five monkeys in group D (one monkey died from cardiac collapse after anesthesia) had seroconverted. Immune enhancement of dengue virus infection is known to occur in humans and monkeys circulating heterologous flavivirus antibodies. In this study, there was no enhancing effect when antibody was mixed with dengue type 2 vaccine virus and injected subcutaneously.

Evaluation of Toxorhynchites Splendens as a Bioassay Host for Dengue Viruses.

Abstract: : Toxorhynchites splendens, a non-hematophagous mosquito was evaluated as a bioassay host for the detection and propagation of dengue viruses. All dengue virus serotypes and strains attained titers in T. splendens comparable to those observed for 2 strains of Aedes aegypti. Peak virus titers occurred in Tx. splendens approximately 6 days postinoculation; however, specific fluorescence for all viruses was not observed in 100% of mosquito heads until 12 days postinoculation. A 100% correlation was noted between specific fluorescence in Tx. splendens heads and the recovery of virus from corresponding thorax-abdomens. The volume of inoculum tolerated by Tx. splendens was approximately 5 timers greater than that injected into Ae. aegypti. Thus, for a given volume of inoculum, the number of Tx. splendens required for virus assays was appreciably less than that needed for Ae. aegypti. The overall survival rate for Tx. splendens following intrathoracic inoculation with dengue viruses was 92%, compared to 41 and 42% for 2 strains of male Ae. aegypti. These findings imply that Tx. splendens would be more efficient than Ae. aegypti as a laboratory assay host for detecting dengue viruses in blood of infected patients and for use in experimental investigations. (Author)

[Dengue outbreak by virus type 4 in French Polynesia. II. Preliminary biological observations on epidemiology and physiopathology of the disease (author's transl)].

Abstract: Authors report some accurate epidemiologic and physiopathologic data about dengue 4. Thanks to virus intrathoracic inoculation in Toxorhynchites amboinensis (Doleshall, 1857), 202 viral strains have been isolated from 633 sera samples. The incidence of the disease has decreased very early after immunization of the whole population and resulted in an eradication of dengue type 1 virus which was endemic in French Polynesia since 1976. Only one type of dengue virus seems to be tolerated in French Polynesian ecosystem in the same time. There is no crossing protection with dengue 1. Clinically, the picture has been the same in both new and previously infected by dengue 1 patients. Duration of viremia during the secondary dengue fever is not shorter than in the primary one. The hemagglutination inhibiting antibodies do not protect patients, but do not result in immune-complexes pathology.

Comparative sensitivity of mosquito inoculation and mammalian cell culture for isolation of some arboviruses in Indonesia.

Abstract: The sensitivity of parenteral inoculation of colony reared male Aedes aegypti and mammalian cell cultures for isolation of Japanese encephalitis virus and dengue virus were compared. The mosquito inoculation technique proved to be more sensitive for the isolation of dengue virus from the sera of febrile patients than did the mammalian cell cultures (Vero and BHK21) employed in these studies. Mosquito inoculation proved to be no more sensitive that the mammalian system for the isolation of Japanese encephalitis virus from field caught female mosquitoes.

Evidence forTwoMechanisms ofDengueVirus Infection of Adherent HumanMonocytes: Trypsin-Sensitiv e Virus Receptors andTrypsin-Resistant ImmuneComplex Receptors

Abstract: Departments ofVirus Diseases andHematology, Walter ReedArmyInstitute ofResearch, Washington, D.C.20012 Trypsin treatment ofadherent humanmonocytes greatly reduced oreliminated theability ofthese cells tosupport dengue virus replication. However, addition of dilute (nonneutralizing) antibody totheinoculum andtheculture mediumresulted inviral yields similar tothose frommonocytes nottreated withtrypsin. Theseresults suggested that viral entry wasfacilitated byphagocytosis ofimmune complexes viaFcreceptors onthemonocytes. Thisconcept wastested by(i) pretreating monocytes withaggregated gammaglobulin, whichresulted ina40fold reduction ofviral yields after infection withdilute antibody-virus complexes and(ii) forming animmunecomplex withvirus, antivirus F(ab')2 fragments, and rabbit anti-human Fab.Whereas F(ab')2 fragments alone wouldnotenhance virus replication intrypsin-treated monocytes, theimmunecomplex containing arabbit Fcpiece didincrease theyield ofdengue virus. Theseresults suggest thatdengue virus caninfect acultured monocyte intwoways: (i) through aviral receptor that istrypsin sensitive or(ii) through anFcreceptor thatisnottrypsin sensitive.

[Dengue outbreak by virus type 4 in French Polynesia. I. General epidemiology - clinical specific aspects (author's transl)].

Abstract: Authors describe an extensive outbreak of dengue 4 virus which is observed for the first time out of its Asian original focus. The whole archipelagos of French Polynesia have been contaminated in a space of four months. Usual form of the disease is typical with lightness of the symptoms. This outbreak has been implicated in the death of a child by shock; and two cases of reversible encephalitis have been certainly caused by this virus. The neurotropism is the main characteristic of dengue virus type 4.