Immunostimulating agents against influenza virus infection in senescent rats

This study investigated the nonspecific immunomodulatory effects of Bacillus Calmette-Guerin (BCG), muramyl dipeptide (MDP) and ascorbic acid (vitamin C) on virus infection of the respiratory tract in Fischer-344 rats. Groups of young adult (12-16 months old) and aged (24-30 months old) rats were given BCG or MDP intranasally or vitamin C orally 6 weeks and again 3 days before an intranasal challenge with influenza virus A/Bangkok/H3N2 (10(6) 50% EID). Titers of hemagglutinin in lung homogenates and the presence of leukocytes in the respiratory tracts served as indices of infection. Lung macrophage functions of animals were determined by measuring random migration and phagocytic yeast cell killing in vitro. Clearance of Staphylococcus aureus from the respiratory tracts of the animals was also measured 4 hours after challenge. - Following BCG treatment, significantly fewer animals developed virus infection. MDP and vitamin C treatments also reduced the numbers of infected rats but did not differ significantly from the untreated control groups. BCG and MDP treatments significantly reduced the numbers of lung leukocytes in virus infected animals. Mean virus titers in the lung homogenates were significantly lower in all treatment groups by the third day of infection. Following all treatments, duration of virus infection was significantly shorter in the aged compared to the young adult groups. Lung macrophage functions increased in all treatment groups. The improvement of aged groups over their controls was greater than that of the young adults compared to their controls. BCG had the greatest protective effects in both the young adult and aged animals; MDP and vitamin C, in that order, were less effective.(ABSTRACT TRUNCATED AT 250 WORDS)     

Histological evolution of caecal lesions in experimental amoebiasis

Histopathological studies in guinea-pigs infected intracaecally with Entamoeba histolytica were carried out longitudinally on days 3, 7, 11, 15, 20 and 35 after infection. Three characteristic modes of development of caecal lesions were observed. These in order of their prevalence were the classical inflammatory cellular infiltration, lymphoid hypertrophy and necrotizing colitis. Occasional amoeboma formation was observed in progesterone-treated animals. This is the first time that histological lesions which mimic the human intestinal amoebiasis have been described in the experimental animal.     

Antibodies to respiratory syncytial virus in a normal community in Chandigarh area, northern India

A survey for the presence of respiratory syncytial (RS) virus antibodies has been carried out in 346 sera from a healthy community in northern India. The results showed that 19.6% of the sera were positive and had a titre of 16 or more. The higher titres were observed more frequently in the younger age groups. There is, therefore, serological evidence for the occurrence of RS virus infection in India.     

Macrophage functions in aging: effects of vitamin C deficiency

Groups of young adult and senescent guinea pigs were fed normal and vitamin C deficient diets for 4 weeks and tested for their peritoneal macrophage functions. Serum levels of vitamin C in deficient animals indicated a progressive state of ascorbic acid deficiency and correlated well with the clinical signs and symptoms of scurvy. Fewer macrophages were obtained from the peritoneal cavities of deficient animals and morphologically they were smaller in size. Adverse effects of vitamin C deficiency were enhanced in aged animals. Significantly greater number of aged animals died by 4 weeks of deficiency. Deficient senescent animals had greater decline in macrophage random migration and bactericidal capacity. Following phagocytic stimuli, superoxide anion generation also significantly decreased. Data suggest that vitamin C deficiency might affect macrophage functions in the aged more profoundly and could compromise parameters of host defenses effective against microbial infections.     

Serological response to cholera revaccination in a semi-closed community in Calcutta

Serological response to cholera revaccination has been studied in a semi-closed community consisting of individuals mostly in the 2-20-years age-group. The subjects had been inoculated against cholera every year at the beginning of the local epidemic season. Pre- and post-vaccination sera were obtained from 29 subjects inoculated with cholera vaccine (test group) and 28 from subjects inoculated with TAB vaccine (control group). These sera were tested for vibriocidal and agglutination titres. The geometrical means of the vibriocidal and agglutination titres of the post-vaccination sera in the test group rose by 490% and 463% respectively. This booster effect was observed mostly in individuals in the 2-14-years age-group, who had low titres (vibriocidal ≤320 and agglutination ≤40) in their prevaccination samples. Revaccination, therefore, appears to be useful as a booster for individuals having low titres.