Presence of serum antibodies against feline panleukopenia computer virus (FPV) correlates with protective immunity against FPV illness, and thus measurement of antibodies can be used to evaluate the specific immune status of individual pet cats. 9 The aim of this pilot study was to determine variations in the effectiveness and security of vaccination of asymptomatic retrovirus-infected pet cats compared with age-matched noninfected pet cats. Materials and methods Study population The protocol of this study was approved by the Government of Upper Bavaria (reference number 55.2-1-54-2532.3-62-11). of retrovirus-infected and non-infected pet cats was performed. Results Pre-vaccination FPV antibody titres ?1:40 were present in 100% (n = 8/8; 95% confidence interval [CI] 62.8C100) of retrovirus-infected and in 77.6% (n = 52/67; 95% CI 66.2C86.0) of non-infected pet cats. An adequate response to vaccination (titre increase ?four-fold) was seen in 1/8 retrovirus-infected pet cats (12.5%; 95% CI 0.1C49.2) compared with 22/67 noninfected pet cats (32.8%; 95% CI 22.8C44.8). In pet cats with high pre-vaccination titres (?1:160), a four-fold titre increase or higher was observed in 1/8 retrovirus infected pet cats (12.5%; 95% CI 0.1C49.2) compared with 4/42 Slc7a7 noninfected pet cats (9.5%; 95% CI 3.2C22.6). None of the eight retrovirus-infected pet cats developed illness or vaccination side effects after vaccination with MLV against FPV within the 28 days. There were no significant variations between organizations: for pre-vaccination titres; for at least four-fold titre raises following vaccination in either all pet cats or the pet cats with high pre-vaccination titres; and concerning adverse effects. Conclusions and relevance All retrovirus-infected asymptomatic pet cats experienced pre-vaccination FPV antibodies indicating safety against panleukopenia. Response of retrovirus-infected pet cats to vaccination was similar Rofecoxib (Vioxx) to the response of non-infected pet cats. Keywords: FIV, FeLV, immunosuppression, FPV, active immunisation, protection Intro Currently, there is argument whether vaccination with altered live computer virus (MLV) is effective and safe in retrovirus-infected pet cats. Security is definitely a concern as MLV vaccines might regain pathogenicity. Thus, current recommendations advise veterinarians to avoid vaccination with MLV in retrovirus-infected pet cats, although there is no definitive evidence for an increased risk.1,2 In addition, it has been discussed whether vaccine-induced immune stimulation might lead to progression of retrovirus infection by altering the unstable balance between the immune system and computer virus. 3 Thus, especially in pet cats with feline immunodeficiency computer virus (FIV) illness, unspecific immune stimulation due to vaccination could lead to improved virus replication caused by activation of latently infected lymphocytes and macrophages, and therefore result in progression of FIV illness. 4 Another concern of vaccination in retrovirus-infected pet cats is the effectiveness of the vaccines. The immune response to vaccination is probably not comparable to the response in non-infected pet cats and it is unclear whether vaccines work at all or whether duration of immunity is definitely shortened in retrovirus-infected pet cats. In experimental studies, FIV-infected pet cats (except in the terminal phase of illness) Rofecoxib (Vioxx) were able to mount appropriate levels of protecting antibodies after vaccination.5,6 In contrast, in one study, vaccination against feline leukaemia computer virus (FeLV) failed to protect pet cats naturally infected with FIV. 7 Similarly, FeLV-infected pet cats were not able to mount an appropriate immune response to vaccines, such as rabies vaccination. 8 So far, no info is definitely available on how FIV-infected or FeLV-infected pet cats in the field respond to vaccination with MLV, such as a vaccine against feline panleukopenia. Presence of serum antibodies against feline panleukopenia computer virus (FPV) correlates with protecting immunity against FPV illness, and thus measurement of antibodies can be used to evaluate the specific immune status of individual pet cats. 9 The aim of this pilot study was to determine variations in the effectiveness and security of vaccination of asymptomatic retrovirus-infected pet cats compared with age-matched noninfected pet cats. Rofecoxib (Vioxx) Materials and methods Study populace The protocol of this study was authorized by the Government of Upper Bavaria (research quantity 55.2-1-54-2532.3-62-11). All pet cats included in the prospective study were offered to the Medical center of Small Animal Medicine, Centre for Clinical Veterinary Medicine, LMU Munich, Rofecoxib (Vioxx) or to different animal shelters for vaccination. All samples, from retrovirus-infected, as well as from non-infected, pet cats were collected between April 2012 and September 2014. Included were healthy pet cats that were offered for vaccination. All pet cats were tested for FIV antibodies and FeLV antigen and then were enrolled into either retrovirus-infected pet cats or controls. Only pet cats between 2 and 6 years of age were included. Only pet cats found to be healthy during physical exam were able to enter the study. Mild gingivitis up to grade 1 (minor swelling, no ulceration, no proliferation, no spontaneous bleeding induced by mild pressure in the alveolar/buccal mucositis score) 10 did not lead to exclusion. Except prophylactic deworming and software of ectoparasiticides, none of them of the pet cats experienced received any medications. FIV and FeLV status was identified in each cat using a commercial quick ELISA.