Characterization of infectious type D retrovirus from baboons.

Infectious virus resembling type D simian retrovirus (SRV) was isolated from Ethiopian baboons (Papio cynocephalus) (SRV-Pc) housed at the University of Washington Regional Primate Research Center. When baboon peripheral blood mononuclear cells (PBMC) or tissues were cocultured with the H-9 human T-cell line or the Raji human B-cell line, large multinucleated syncytia positive for SRV-2 antigens were observed microscopically. Immunoblot analysis of purified SRV-Pc from cell culture supernatants demonstrated that the viral core and envelope proteins reacted with rabbit anti-SRV-2 serum. Fresh PBMC and cocultured cells were positive by polymerase chain reaction using two different sets of SRV-2 primers. Preliminary sequence analysis of two separate isolates from portions of the SRV-Pc p27 and gp20 regions revealed homology with SRV-1, SRV-2, and Mason-Pfizer monkey virus. The homologies in the p27 segment were 91-94% and the homologies in the gp20 segment were 72-75%.

Effect of dosing frequency on ZDV prophylaxis in macaques infected with simian immunodeficiency virus.

The effect of dosing frequency on zidovudine (ZDV) prophylaxis against simian immunodeficiency virus (SIV) infection was examined in long-tailed macaque monkeys (Macaca fascicularis). The results indicate that dosing frequency is extremely important for drug efficacy. The monkeys were divided into three groups based on dosing frequencies of 6-, 8-, or 12-h intervals. All were given a total daily dose of 100 mg/kg of ZDV. The drug was administered subcutaneously starting 24 h before SIV inoculation, and treatment continued for an additional 28 days. With the total daily dose held constant, ZDV was most therapeutic when administered at 12-h intervals, less effective at 8-h intervals, and least effective at 6-h intervals. These results indicate that early ZDV treatment based on infrequent but high dosages may increase the antiretroviral effect of the drug. These findings could serve as a model for ZDV chemoprophylaxis in humans. In cases involving accidental exposure to SIV or human immunodeficiency virus (HIV-1 or HIV-2), immediate, high-dosage therapies may be most therapeutic.

Some clinical and epidemiological observations on virologically confirmed dengue hemorrhagic fever.

This study is a part of a one year prospective study on dengue hemorrhagic fever (DHF) carried out in the Department of Pediatrics, Sumber Waras Hospital in West Jakarta. Viral isolation and serologic analysis for DHF were done by Namru-2 in Jakarta. The subjects were 151 virologically confirmed DHF Patients admitted to the Department of Pediatrics during the period of September 1987-June 1988, consisting of 82 boys and 69 girls of 6 months-15 years old. The predominant age group was 5 to 9 years, representing 49.7% subjects. Dengue virus was isolated from sera during the first 8 days of illness and in 139 (42.1%) during the first 5 days of illness. Dengue virus type 1, 2, 3 and 4 were isolated from 16.6%, 13.2%, 69.5% and 0.7% subjects, respectively. The clinical manifestations revealed no striking differences between dengue 3 and others except for thrombocytopenia and shock. High fever, hemoconcentration and thrombocytopenia on admission was observed in 30.5%, 8.6% and 8.6% of subjects, respectively. Dengue shock syndrome (DSS) were observed in 23 (15.2%) with 3 (2%) fatal cases. Dengue virus serotype 3 was observed in 20 out of 23 DSS cases (86.9%) and all fatal cases were associated with dengue type 2. This study revealed that dengue 3 is the predominant virus circulating during recent epidemics and is associated with more severe clinical manifestation and with a higher incidence rate of living area.

Use of Indonesian non-human primate erythrocytes for measles hemagglutination inhibition serology.

The use of erythrocytes (RBC) from Presbytis cristata, P. melalophus and Macaca fascicularis for measles hemagglutination inhibition serologies is presented. These primates can provide a ready supply of RBC for diagnostic reagent use in areas of the world where the African green monkey or rhesus macaque are not available. Individuals of each species are useful but must be screened for hemagglutination ability of their erythrocytes. The animal can then be chosen that has erythrocytes which best agglutinate with the antigen being used.

Complex-specific immunoglobulin M antibody patterns in humans infected with alphaviruses.

Sera from humans with serologically confirmed eastern equine encephalitis, western equine encephalitis, Pogosta (Ockelbo), Mayaro, Ross River, and chikungunya virus infections were tested by immunoglobulin M (IgM) antibody capture enzyme immunoassay. Diagnostically useful IgM antibody titers were detected, and selected sera with high IgM antibody titers were tested for IgM antibody with nine heterologous alphaviruses. The results provide evidence for the complex specificity of IgM antibody and indicate the usefulness of this test in both individual cases and epidemic situations.

Clinical trials with canine distemper vaccines in exotic carnivores.

Two types of killed canine distemper virus (CDV) vaccine and a modified-live CDV vaccine were clinically evaluated in four species of exotic carnivores. In 16 trials in which 13 red pandas (Ailurus fulgens) were given the killed vaccine, only 1 animal had a virus-neutralization titer that exceeded 1:100. A red panda given modified-live CDV vaccine deemed safe for gray foxes and ferrets died of bacterial pneumonia 16 days later. There was no pathologic evidence of canine distemper in that panda. The same modified-live vaccine proved to be immunogenic and safe in 12 bush dogs (Speothos venaticus), 5 maned wolves (Chrysocyon brachyurus), and 3 fennec foxes (Fennecus zerda) in which virus-neutralization titers often exceeded 1:512 and persisted for several months after vaccination.

Parvovirus enteritis in vaccinated juvenile bush dogs.

Parvovirus enteritis developed in 10 of 17 vaccinated juvenile bush dogs (Speothos venaticus) from 4 litters in a 5-month period. Nine dogs died. The first outbreak involved 6 of 9 bush dogs from 2 litters. Each had been vaccinated with a killed feline-origin parvovirus vaccine at 11 and 14 weeks of age. The 6 affected dogs became ill at 29 weeks of age and died. The second outbreak involved a litter of 6 bush dogs. Each had been vaccinated every 2 weeks starting at 5 weeks of age. Two were isolated from the colony at 16 weeks of age for treatment of foot sores. Three of the 4 nonisolated dogs developed parvovirus enteritis at 20 weeks of age; 2 died at 6 and 8 days, respectively, after onset of signs. The 3rd outbreak involved a litter of 2 bush dogs. Both had been vaccinated every 2 to 3 weeks, starting at 6 weeks of age. One of these dogs became ill at 17 weeks and died 13 days later. A litter of 6 maned wolves (Chrysocyon brachyurus) and a litter of 3 bush dogs were isolated from their parent colonies at 13 and 15 weeks of age, respectively. Each animal had been vaccinated weekly, beginning at 8 weeks of age, using an inactivated canine-origin parvovirus vaccine. None of the isolated animals developed the disease. Serologic testing during isolation did not reveal protective titers (greater than or equal to 1:80) against canine parvovirus in the bush dogs until they were 23 weeks old, whereas protective titers developed in the maned wolves when they were 14 to 18 weeks old. One hand-raised bush dog was vaccinated weekly, beginning at 8 weeks of age, and a protective titer developed by 21 weeks of age. It was concluded that the juvenile bush dogs went through a period during which maternal antibodies interfered with immunization, yet did not protect against the disease. When the pups were isolated from the colony during this period, then vaccinated repeatedly until protective titers developed, the disease was prevented.

Prevention of murine rotavirus infection with chicken egg yolk immunoglobulins.

Passive protection of infant mice against murine rotavirus was achieved with use of immunoglobulins from the eggs of chickens. Immunoglobulins were obtained by vaccinating hens with simian rotavirus, collecting the eggs after a high level of immunoglobulins was reached in the hen's serum, and isolating the water-soluble fraction from these eggs. The water-soluble fraction was then given twice daily to three-day-old mice to protect them from infection with murine rotavirus. The protection was found to decrease the infection rate from 90% to 15% with use of a standard dose of virus.

Rotavirus antibody in chickens as measured by enzyme-linked immunosorbent blocking assay.

The antibody titer of 202 chickens to SA-11 rotavirus was determined by enzyme-linked immunosorbent blocking assay. The chickens were from 15 separate flocks on six farms. The titer was detectable (1:18 or greater dilution) in 43% of the chickens. The wide variation in infection rate between flocks on individual farms (0% to 90%) indicated there is probably not significant transmission of the virus between flocks on the farm. Significant differences in numbers of serotest-positive birds were found between separate farms, possibly reflecting different management practices.