[The improvement of immunobiological preparations against leptospirosis. An experimental study of a new concentrated purified vaccine against icterohemorrhagic leptospirosis for human immunization]. / Sovershenstvovanie immunobiologicheskikh protivoleptospiroznykh preparatov. Eksperimental'noe izuchenie novoi kontsentrirovannoi ochishchennoi vaktsiny protiv ikterogemorragicheskogo leptospiroza dlia immunizatsii liudei.

The findings of the study of immunological structure of the population in regions endemic for leptospirosis indicate that the immune status of humans makes it impossible to obtain titrated blood sera for the preparation of antileptospirosis immunoglobulin. The data obtained in the study of the immunobiological properties of a new concentrated vaccine against icterohemorrhagic leptospirosis show the possibility of using this vaccine for the immunization of donors with the aim of obtaining blood sera to be used as raw material for the production of immunobiological preparations.

Effect of cyclophosphamide treatment on clinical and serologic response of rats to infection with Leptospira interrogans serovar icterohaemorrhagiae.

Young albino rats were immunosuppressed with cyclophosphamide and exposed to virulent and low-virulence Leptospira interrogans serovar icterohaemorrhagiae 820K. In rats exposed to virulent and low virulence leptospires, microscopic agglutinating antibody responses occurred later, and longer leptospiremic phase and more massive tissue invasion by the organisms were observed in immunosuppressed rats than in immunocompetent controls. Clinical and pathologic signs of illness were more severe in the immunosuppressed animals than in immunocompetent controls. When exposed to low-virulence leptospires, immunosuppressed rats became infected and developed signs of illness and 2 of 16 died. Immunocompetent rats rapidly developed a humoral response and did not develop any signs of illness, and with 1 exception, organisms were not recovered from any tissues.

Experimental infection of calves and sheep with Leptospira interrogans serovar balcanica.

Two of four calves inoculated with Leptospira interrogans serovar balcanica developed low microscopic agglutinating (MA) titres to serovar hardjo. A third calf had an MA titre of 1:1024 by day 19 post-inoculation (PI). Transient leptospiruria was recorded in one calf on days 12 and 13 PI. An in-contact calf did not seroconvert. None of the calves had fever or other clinical signs of disease. Four ewes inoculated with balcanica developed MA titres to hardjo by day 13 PI, and a transient leptospiruria between days 14 and 25 PI. None of the ewes showed any evidence of clinical disease and three of them delivered healthy lambs 22 to 64 days PI. One ewe had mild lesions of focal interstitial nephritis.