Prevention of Murine Sarcoma Virus Oncogenesis in Offspring of Immunized Female Mice

Abstract

Summary.-BALB/c mice born to and nursed by females immunized against MSV-M showed a reduced tumour incidence and a high tumour regression rate following MSV-M injection at 7-14 days of age. Females immunized long before mating could also confer protection to their offspring whereas females immunized after parturition could not. A reduced number of tumours was observed in 3 out of 14 MSV-M injected litters whose mothers had been previously exposed to the virus while nursing infected offspring. Sera from suckling mice born to and nursed by immunized mothers contained MSV-M neutralizing antibody as shown by an in vitro focus reduction assay. Cell-free extracts from mice which developed leukaemia after MSV-M inoculation were tested for oncogenic activity in 1-week old mice. Out of 6 extracts, 4 induced typical MSV-M tumours and 2 caused leukaemias.

Is There a Maternally Induced Immunological Imprinting Phase à la Konrad Lorenz?

“…Hence, maternal immunization can be utilized to increase the neonatal antibody titers which protect the offspring against environmental pathogens such as bacterial infections [ 5–7], bacterial intoxication [ 8–10] or a variety of viral diseases [ 11] caused for instance by respiratory syncytial virus (RSV) [ 12], rotavirus [ 13], influenza virus [ 14–16], haemorrhagic fever renal syndrome virus [ 17], reovirus [ 18] or poliovirus [ 19]. Moreover, even tumor immunity can be transferred from immunized female mice to the offspring [ 20–22]. Collectively, these observations provide the basis for a maternal vaccination which is already widely practiced in veterinary medicine [ 23, 24], and also in humans, mothers may be vaccinated with the aim to protect their babies against certain infectious diseases [ 7–9, 19, 25].…”

Tumor Induction by Murine Sarcoma Virus in Akr and C58 Mice

“…Thus, it may be possible that, as suggested for the avian Rous sarcoma system, development and growth of M-MSV tumors in the mouse follows a nonclonal kinetics which is dependent upon a constant high rate of virus replication and continuous recruitment of newly infected transformed cells. When virus synthesis is slowed down by a host reaction or antibody transfer, prevention of tumor formation as well as tumor regression may result (35). At variance with this line of reasoning is the observation that some of the MSV-induced tumors revealed morphological features suggesting a proliferative pattern of the clonal type.…”