Reactions of Monkeys to Experimental Respiratory Infections. III. Response to Mixtures of Influenza Virus and Streptococcus. ∗

Abstract

In earlier studies 1 employing mice, a shorter survival period and a greater proportion of deaths were observed in those animals which received mixtures of Streptococcus hemolyticus, Group C, and influenza-A virus, than in those receiving only one agent alone. The present report records particularly the hematological reactions in monkeys in which one infection was superimposed upon the other via the intranasal route.

Methods. The preparation of inocula, the dosages employed, and the method of administration were carried out as previously described. 2 , 3 When the two agents were given simultaneously the concentrations were so adjusted that 3 cc of the mixture contained the full dosage of each agent.

Results. Clinical Characteristics. All monkeys receiving both agents, in whatever order, survived the infections and manifested only minimal clinical evidences of disease, except monkey No. 3 (Fig. 1-D), which became acutely ill and died with an overwhelming streptococcal septicemia.

Experiment 1. Simultaneous Inoculation with Virus and Streptococci. The 2 monkeys receiving a mixture of virus and streptococci, each manifested within 24 hours a marked polymorphonuclear leucocytosis. The total white blood cells increased from 12,000 to 56,000 (granulocytes 4900 to 44,300) in No. 7 (Fig. 1-A), and from 13,000 to 39,000 (granulocytes 8800 to 33,000) in No. 8. Both animals, between the 11th and 15th days after inoculation, developed a definite granulocytopenic leucopenia with, in one instance, a relative, and in the other an absolute lymphocytosis, suggesting a masked and delayed reaction to virus. Specific neutralizing antibodies were demonstrated.

Experiment 2. Inoculation with Streptococcus Followed by Virus. Four monkeys (Nos. 9, 10, 12, 13) receiving a primary inoculation of hemolytic streptococci, developed the usual leucocytosis within 24 to 48 hours (Fig. 1-B) but, when inoculated 4 days later with the virus, only one of the animals showed the typical inhibition of granulocytes which has characterized all initial, uncomplicated viral infections.