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Mucosal transmission of cell-associated and cell-free feline immunodeficiency virus
M J Burkhard1, L A Obert, L L O'Neil
1Department of Pathology, College of Veterinary Medicine, Colorado State University, Fort Collins 80523, USA.
Abstract:
Mucosal infection by feline immunodeficiency virus (FIV) was assessed via a single exposure of the vaginal or rectal mucosa to either infectious peripheral blood mononuclear cells (PBMCs), infectious plasma, or cell-free cultured virus. All cats inoculated with cell-free cultured virus (100 or 400 TCID) and 9 of 10 cats inoculated with infected PBMCs (2 x 10(7) or 2 x 10(5)) became persistently viremic within 3 weeks. Neither cat inoculated with 2 x 10(3) PBMCs became viremic. Rectal and vaginal exposure were equally effective routes to induce viremia. CD4+ T cells and mitogen-stimulated PBMC proliferation declined in all infected cats. However, a transient PBMC proliferative response to FIV p24gag occurred in most virus-exposed cats, especially those that did not develop detectable infection. FIV was not transmitted by mucosal exposure to infectious virus in plasma (100 TCID), a dose > 10-fold that needed for infection by parental injection. In vitro studies suggested that a plasma heat-stable virus-neutralizing factor may be associated with failure of plasma virus to establish infection via the mucosal route. Mucosal FIV infection provides a new model with which to study early stages of infection and intervention in transmucosal lentivirus infections.
Insights
Feline immunodeficiency virus (FIV) can infect cats through vaginal or rectal exposure to infected cells or cultured virus. Mucosal FIV infection offers a new model for studying early lentivirus infection stages.
Area of Science:
- Veterinary Virology
- Immunology
- Infectious Diseases
Background:
- Feline immunodeficiency virus (FIV) is a lentivirus affecting cats globally.
- Understanding FIV transmission routes is crucial for prevention and treatment strategies.
- Mucosal transmission is a key route for many lentiviruses, including HIV.
Purpose of the Study:
- To investigate the efficacy of different routes and methods of FIV exposure for inducing mucosal infection in cats.
- To characterize the early immunological changes following mucosal FIV infection.
- To establish a novel animal model for studying transmucosal lentivirus infections.
Main Methods:
- Cats were exposed via vaginal or rectal mucosa to infectious peripheral blood mononuclear cells (PBMCs), infectious plasma, or cell-free cultured FIV.
- Viremia was monitored, and immunological parameters including CD4+ T cell counts and PBMC proliferation were assessed.
- In vitro studies were conducted to investigate potential mechanisms of viral non-transmission.
Main Results:
- Single mucosal exposure to cell-free cultured FIV or infected PBMCs effectively induced persistent viremia in cats.
- Vaginal and rectal routes demonstrated equal efficacy in establishing FIV infection.
- Infection led to a decline in CD4+ T cells and PBMC proliferation, with a transient response to FIV p24gag in some cats.
- Mucosal exposure to infectious FIV in plasma did not result in infection, potentially due to a heat-stable neutralizing factor.
Conclusions:
- Mucosal routes, particularly via cell-free virus or infected PBMCs, are effective for FIV transmission in cats.
- This study establishes a new feline model for investigating early events in transmucosal lentivirus infection.
- The findings highlight the importance of cell-associated or cell-free cultured virus over plasma for mucosal FIV transmission.