Studies on the inheritance in the red raspberry of immunities from three nematode-borne viruses

Lethal or chronic diseases of the raspberry caused by the nematodeborne viruses raspberry ringspot, arabis mosaic and tomato black ring can cause serious reductions in the productivity of raspberry plantations, but the existence of clear-cut immunities from these diseases provides a basis for control through plant breeding. The inheritance of these immunities was studied by means of graft tests on families of raspberry seedlings. Immunity from each virus was found to be dominant to susceptibility, but there was evidence that more than one gene was concerned in each case: while it was not possible to decide whether the second gene was a dominant complementary or a linked recessive affecting the viability of the immune segregates, the frequent occurrence in the raspberry of aberrant segregation ratios due to such lethal genes makes the latter explanation the more probable. There was also evidence of linkage between the genes for the three immunities. The experiment confirmed the practicability of breeding to incorporate genes for immunities from these three viruses into new raspberry varieties.     

Modulation of acute and latent herpes simplex virus infection in C57BL/6 mice by adoptive transfer of immune lymphocytes with cytolytic activity

The ability of highly lytic herpes simplex virus (HSV) cytolytic T lymphocytes to modulate the interaction between the murine host (adult C57BL/6 [H-2b] mice) and HSV type 1 Patton resulting in acute infection in the footpad and latent infection in the sensory lumbosacral dorsal root ganglia (L6, L5, L4, and L3) innervating the footpad was investigated. Results indicated that a critical threshold level of infectious HSV was required to establish infection. The adoptive transfer of cytolytic T lymphocytes derived from in vitro cultures after restimulation with HSV-infected, syngeneic stimulator cells exhibiting class I H-2-restricted, L3T4- Lyt-2+ HSV-specific cytolytic activity immediately before infection with a high dose of HSV reduced the levels of infectious HSV recovered from the footpad tissue during acute infection and the levels of latent HSV reactivated from the dorsal root ganglia to levels expected from mice infected with a low dose. Depletion of Lyt-2+ cells from the transferred population abrogated the protective ability, while depletion of L3T4+ cells had little effect. These results suggest that functionally lytic HSV-specific cytolytic T lymphocytes present at the time of HSV infection have the potential to participate in the control of the acute infection and in the subsequent establishment of latent infection.     

Genital mucosal transmission of simian immunodeficiency virus: animal model for heterosexual transmission of human immunodeficiency virus.

An animal model for the heterosexual transmission of human immunodeficiency virus (HIV) was developed by the application of simian immunodeficiency virus (SIV) onto the genital mucosas of both mature and immature, male and female rhesus macaques. Virus preparations were infused into the vaginal vaults or the urethras (males) of the animals through a soft plastic pediatric nasogastric feeding tube. The macaques that were infected by this route (six males and nine females) developed SIV-specific antibodies, and SIV was isolated from peripheral mononuclear cells of all seropositive animals. One male and one female infected by this route developed severe acquired immunodeficiency syndrome-like disease with retroviral giant-cell pneumonia. As few as two inoculations of cell-free SIV containing 50 50% tissue culture infective doses induced persistent viremia. Cell-free virus preparations were capable of producing infection by the genital route. Much higher doses of virus were required to transmit SIV by this route than are required for transmission by intravenous inoculation. Thus, it appears that the mucous membranes of the genital tract act as a barrier to SIV infection. Spermatozoa and seminal plasma were not required for the genital transmission of SIV. Rarely, SIV was recovered from mononuclear cells in semen and vaginal secretions. The SIV-rhesus macaque model is suitable for assessing the role of cofactors in heterosexual transmission of HIV and will be useful for testing the effectiveness of spermicides, pharmacologic agents, and vaccines in preventing the heterosexual transmission of HIV.