1.Sperm was known to be Immunosuppressive. 2.Antigen overload might be Immunosuppressive. 3.Amyl Nitrate is known to be Immunosuppressive. 4.Blood products (AIDS in hemophiliacs). 5.Retrovirus was discovered in AIDS Patients. Retroviruses The retroviruses can be divided into two groups: Transforming viruses The transforming retroviruses can cause cancer.This virus often carries an oncogene. Bovine leukemia virus Avian type C virus Mammalian type C virus Human T-cell lymphotrophic virus type 1 and 2 (HTLVI and HTLV2)HTLV1 causes leukemia and does not have oncogene. Cyotpathic Viruses Visna virus Caprine arthritis encepalitis virus equine infectious animal virus feline immunodeficiency virus Immunodeficiency virus (HIV1,HIV2,SIV) Both and to STV than they are to each other.HIV and HIV2 only have 40%DNA homology whereas HIV2 has 75%homology with SIV.There is also known cross species transfer of SIV. 1. Sperm was known to be Immunosuppressive. 2. Antigen overload might be Immunosuppressive. 3. Amyl Nitrate is known to be Immunosuppressive. 4. Blood products (AIDS in hemophiliacs). 5. Retrovirus was discovered in AIDS Patients. Retroviruses The retroviruses can be divided into two groups: Transforming viruses The transforming retroviruses can cause cancer. This virus often carries an oncogene. Bovine leukemia virus Avian type C virus Mammalian type C virus Human T-cell lymphotrophic virus type 1 and 2 (HTLV1 and HTLV2) HTLV1 causes leukemia and does not have oncogene. Cyotpathic Viruses Visna virus Caprine arthritis encepalitis virus equine infectious animal virus feline immunodeficiency virus Immunodeficiency virus (HIV1, HIV2, SIV) Both HIV1 and HIV2 are more closely related to SIV than they are to each other. HIV1 and HIV2 only have 40% DNA homology whereas HIV2 has 75% homology with SIV. There is also known cross species transfer of SIV