Epidemiologic survey of feline leukemia virus in domestic cats on Tsushima Island, Japan: management strategy for Tsushima leopard cats

Abstract

The Tsushima leopard cat (TLC) Prionailurus bengalensis euptilurus, a subspecies of P. bengalensis, is designated a National Natural Monument of Japan, and lives only on Tsushima Island, Nagasaki Prefecture, Japan. TLCs are threatened by various infectious diseases. Feline leukemia virus (FeLV) causes a serious infectious disease with a poor prognosis in cats. Therefore, the transmission of FeLV from Tsushima domestic cats (TDCs) to TLCs may threaten the TLC population. We investigated the FeLV infection status of both TDCs and TLCs on Tsushima Island by screening blood samples for FeLV p27 antigen and using PCR to amplify the full-length FeLV env gene. The prevalence of FeLV was 6.4% in TDCs and 0% in TLCs. We also demonstrated that the virus can replicate in the cells of TLCs, suggesting its potential cross-species transmission. The viruses in TDCs were classified as genotype I/clade 3, which is prevalent on a nearby island, based on previous studies of FeLV genotypes and FeLV epidemiology. The FeLV viruses identified on Tsushima Island can be further divided into 2 lineages within genotype I/clade 3, which are geographically separated in Kamijima and Shimojima, indicating that FeLV may have been transmitted to Tsushima Island at least twice. Monitoring FeLV infection in the TDC and TLC populations is highly recommended as part of the TLC surveillance and management strategy.

Identification of Felis catus Gammaherpesvirus 1 in Tsushima Leopard Cats (Prionailurus bengalensis euptilurus) on Tsushima Island, Japan

“…Our observation that FeLV infection was not associated with an increased likelihood of FcaGHV1 DNA detection is congruent with previous reports [ 14 , 16 , 17 , 19 ] but contrasts with specific findings from Singapore where FeLV infection was significantly associated with FcaGHV1 detection [ 14 ]. On Tsushima Island, the prevalence rates of FeLV infection in Kamijima and Shimojima were 3.1% and 16.2%, respectively [ 6 ]. However, data from epidemiological survey of feline viruses in Singapore, and of particular interest FeLV, were inconsistent [ 19 ].…”

“…The majority of these were from animals killed by vehicles. In total, 89 TLCs (60 blood and 29 spleen) samples were available for this study [ 6 ].…”

“…Blood samples from domestic cats were donated by the Tsushima Animal Medical Center, a nonprofit animal hospital on the island. The domestic cats included both indoor-only and free-roaming cats brought by their owners to the center between 2009 and 2016 [ 6 ].…”

“…We recently reported the prevalence of feline leukemia virus (FeLV) infection in domestic cats on Tsushima Island. We did not detect FeLV in TLCs; however, we demonstrated that the virus could replicate in their cells [ 6 ].…”

“…The disease outcome and risks associated with the transmission of FcaGHV1 from domestic cats to TLCs is currently unknown. Therefore, monitoring the TLC population for infectious diseases is highly recommended as part of a surveillance and management strategy since measures required to control disease in wild populations can be challenging [ 6 ]. The expansion of human habitats facilitates the spill-over of feline pathogens from domestic cats into wildlife populations; thus, determination of the pathogenic potential of FcaGHV1 is a priority for feline, human and wildlife health [ 14 ].…”