Primary Infection Period Research Articles

Primary Human Immunodeficiency Virus Infection: Clinical and Serologic Aspects

The identification of characteristic clinical, serologic, and immunologic responses to primary HIV infection has contributed greatly to our understanding of the natural history of HIV infection. Subjects usually present with a mononucleosis-like illness and during the period of primary infection there is a characteristic four-phase T cell response. Early serologic findings of infection include IgM antibody and free HIV p24 antigen. Tests for mononucleosis yield negative results, but atypical lymphocytosis may be present. We believe there are three primary goals for future research into primary HIV infection: to further define the features of this phase of infection, to develop early intervention strategies effective against HIV, and to further develop and foster education strategies that will prevent primary HIV infection.

Infectious bovine rhinotracheitis virus infection in bulls, with special reference to preputial infection.

In an experiment with infectious bovine rhinotracheitis (IBR) virus in two bulls, observed over a period of 122 weeks, the pattern of virus release was studied. Recurrent, unprovoked release of virus was demonstrated after one year in a nasal washing from one of the bulls and in preputial washings of both on 13 and 4 occasions, respectively, and finally in weeks 113 and 110, although clinical disease was not observed. During periods of recurrent virus release, concentrations of virus in the prepuce were generally much lower than during the period of primary infection; usually, however, they were not of negligible titer. The frequency of such periods and the virus titers observed strongly suggest that an IBR antibody carrier should always be considered as a potential source of infection to other animals. When virus was demonstrated in semen an almost equal amount was found in the preputial washing (50 ml). In week 120, virus replication in the respiratory tract and prepuce was induced in both bulls by prednisolone injections. It is concluded that antibody carriers will rarely attain a state of absolute immunity.

Infectious Bovine Rhinotracheitis Virus Infection in Bulls, with Special Reference to Preputial Infection

In an experiment with infectious bovine rhinotracheitis (IBR) virus in two bulls, observed over a period of 122 weeks, the pattern of virus release was studied. Recurrent, unprovoked release of virus was demonstrated after one year in a nasal washing from one of the bulls and in preputial washings of both on 13 and 4 occasions, respectively, and finally in weeks 113 and 110, although clinical disease was not observed. During periods of recurrent virus release, concentrations of virus in the prepuce were generally much lower than during the period of primary infection; usually, however, they were not of negligible titer. The frequency of such periods and the virus titers observed strongly suggest that an IBR antibody carrier should always be considered as a potential source of infection to other animals. When virus was demonstrated in semen an almost equal amount was found in the preputial washing (50 ml). In week 120, virus replication in the respiratory tract and prepuce was induced in both bulls by prednisolone injections. It is concluded that antibody carriers will rarely attain a state of absolute immunity.

Relationship between Body Weight and Food and Water Intake in Trichinella spiralis-Infected Guinea Pigs

Guinea pigs were studied during a 28-day period following a single oral dose of Trichinella spiralis larvae to obtain information on the lethality of T. spiralis for this host and the effect of infec- tion on body weight and food and water consumption. Survival time in guinea pigs administered graded doses of 5-, 10-, 15-, 20-, 25-, and 30,000 larvae followed a dose-dependent pattern, decreasing as the dose increased. The oral LD5o for a 28-day infection was calculated as 49 + 2 larvae per gram of body weight. Marked signs associated with trichinosis in the guinea pig were diarrhea, a reduction in weight gain, and reduced food and water consumption. Other signs were a roughness of the coat, inflamma- tion around the eyes and reduced activity. The rate of weight gain for infected guinea pigs was in- versely related to the size of the initial dose and was significantly lower than that for uninfected con- trols. Food and water intake studies showed that (a) when uninfected and infected guinea pigs were given food and water ad libitum, the uninfected animals consumed greater daily amounts of food and water than animals infected with 10,000 larvae; (b) this higher food consumption was associated with an increased rate of weight gain; (c) uninfected guinea pigs maintained on a diet restricted to that consumed by paired infected animals showed a higher rate of weight gain than the infected guinea pigs. Animals experimentally infected with Trich- inella spiralis often show roughened hair, apathy, diarrhea, and weight loss. Of these signs weight loss has probably been studied most closely. It is generally assumed that the failure of these animals to gain weight at a normal rate is due in large part to lowered food consumption. However, the amount of weight loss which can be attributed to a de- crease in food intake is obscure due to the loss that may be caused by other manifestations of infection. Possibly a decrease in body weight may reflect not only a reduced appetite (as evidenced by a decreased dietary intake) but other factors such as impaired intestinal ab- sorption and diarrhea. This investigation was undertaken to clarify the relationship between food and water con- sumption and weight loss in T. spiralis-infected guinea pigs. Experiments were all performed within a primary infection period of 28 days and were designed to study the virulence of T. spiralis in the guinea pig, with special ref- erence to lethal and sublethal dose values, changes in body weight, and changes in food and water consumption during infection.