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Reversal of the Progression of Fatal Coronavirus Infection in Cats by a Broad-Spectrum Coronavirus Protease Inhibitor.

Kim Y, Liu H, Galasiti Kankanamalage AC, Weerasekara S, Hua DH, Groutas WC, Chang KO, Pedersen NC - PLoS Pathog. (2016)

Bottom Line: The increasing risks of highly virulent coronavirus infections in humans or animals call for effective antiviral drugs, but no such measures are yet available.Experimental FIP is 100% fatal once certain clinical and laboratory signs become apparent.These results indicate that continuous virus replication is required for progression of immune-mediated inflammatory disease of FIP.

View Article: PubMed Central - PubMed

Affiliation: Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America.

ABSTRACT
Coronaviruses infect animals and humans causing a wide range of diseases. The diversity of coronaviruses in many mammalian species is contributed by relatively high mutation and recombination rates during replication. This dynamic nature of coronaviruses may facilitate cross-species transmission and shifts in tissue or cell tropism in a host, resulting in substantial change in virulence. Feline enteric coronavirus (FECV) causes inapparent or mild enteritis in cats, but a highly fatal disease, called feline infectious peritonitis (FIP), can arise through mutation of FECV to FIP virus (FIPV). The pathogenesis of FIP is intimately associated with immune responses and involves depletion of T cells, features shared by some other coronaviruses like Severe Acute Respiratory Syndrome Coronavirus. The increasing risks of highly virulent coronavirus infections in humans or animals call for effective antiviral drugs, but no such measures are yet available. Previously, we have reported the inhibitors that target 3C-like protease (3CLpro) with broad-spectrum activity against important human and animal coronaviruses. Here, we evaluated the therapeutic efficacy of our 3CLpro inhibitor in laboratory cats with FIP. Experimental FIP is 100% fatal once certain clinical and laboratory signs become apparent. We found that antiviral treatment led to full recovery of cats when treatment was started at a stage of disease that would be otherwise fatal if left untreated. Antiviral treatment was associated with a rapid improvement in fever, ascites, lymphopenia and gross signs of illness and cats returned to normal health within 20 days or less of treatment. Significant reduction in viral titers was also observed in cats. These results indicate that continuous virus replication is required for progression of immune-mediated inflammatory disease of FIP. These findings may provide important insights into devising therapeutic strategies and selection of antiviral compounds for further development for important coronaviruses in animals and humans.

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Antiviral treatment of symptomatic cats with FIP.(A) In two independent studies, cats were inoculated with FIPV at day 0 and GC376 treatment was started after they developed lymphopenia and clinical symptoms. In the 2nd study, cats received supportive treatment for five days (shaded boxes), which was discontinued prior to antiviral treatment. The arrows and forward slashes indicate antiviral treatment duration and euthanasia, respectively. dpi, days post infection. (B-D) Responses of cats with FIP to antiviral treatment: body temperature (B), percent body weight changes (C) and lymphocyte counts (D) over time. The shaded areas indicate the normal range of values. Colored arrows located between panels B and D indicate the treatment duration for each cat.
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ppat.1005531.g003: Antiviral treatment of symptomatic cats with FIP.(A) In two independent studies, cats were inoculated with FIPV at day 0 and GC376 treatment was started after they developed lymphopenia and clinical symptoms. In the 2nd study, cats received supportive treatment for five days (shaded boxes), which was discontinued prior to antiviral treatment. The arrows and forward slashes indicate antiviral treatment duration and euthanasia, respectively. dpi, days post infection. (B-D) Responses of cats with FIP to antiviral treatment: body temperature (B), percent body weight changes (C) and lymphocyte counts (D) over time. The shaded areas indicate the normal range of values. Colored arrows located between panels B and D indicate the treatment duration for each cat.

Mentions: To investigate the efficacy of GC376, we conducted two independent studies. In these studies, antiviral treatment was started after the infected cats developed the typical laboratory finding of absolute lymphopenia and clinical symptoms to determine whether treatment with GC376 is effective in reducing the severity of symptoms or fatality. In both studies, the infected cats were monitored daily for fever, body weight, and outward disease signs and weekly for lymphocyte counts. In the first efficacy study, four SPF cats of 8–10 months of age (P02, P03, P07 and P10) were intraperitoneally administrated with a cat-passaged serotype I FIPV (FIPV-m3c-2) [12, 17, 34]. Following infection, they developed lymphopenia and clinical symptoms including inapparent or mild ascites within 14–20 days post infection (dpi) (Table 1). In the second study, the ascites of four SPF cats of 8–10 months of age inoculated with the same virus (P15, P16, P17 and P24) were allowed to progress to more profound, classical abdominal effusions, which closely resemble those of cats with naturally-occurring FIP frequently presented at the clinics (Table 1). However, in order to alleviate suffering, the latter four cats were given meloxicam, a non-steroidal anti-inflammatory drug, and subcutaneous fluids prior to antiviral treatment. This supportive treatment was discontinued before antiviral drug treatment commenced. The eight cats from both studies developed jaundice, inapparent to profound ascites, absolute lymphopenia (134~676/μl, reference range 1,200 to 8,000/μl) and high fever (up to 41.1°C) (Fig 3B and 3D, Table 1) before antiviral treatment was started. They also lost body weight up to 13.6% of their pre-infection weight during this same period (Fig 3C). When they reached this stage, twice daily s.c. administration of GC376 at 5–10 mg/kg/dose was started. These cats were treated for 14–20 days, except for P15 and P16 that were euthanized after 4 and 7 days after starting antiviral treatment based on the severe nature of their clinical signs (Fig 3A). All six remaining cats showed rapid improvement in attitude and resolution of fever (Fig 3B). The profound absolute lymphopenia observed in all cats prior to antiviral treatment also returned to normal before the next blood testing one week later (Fig 3D) and weight losses were reversed and normal growth resumed (Fig 3C). Ascites and scrotal swelling indicative of peritonitis also gradually resolved after a week of antiviral treatment. All cats that received antiviral treatment for 14–20 days appeared normal by clinical observation and laboratory testing. The six recovered cats from both studies have remained healthy showing no signs of relapse during an observation period up to 8 months. These experiments demonstrate that the protease inhibitor was able to reverse disease progression when treatment was initiated at advanced clinical stages of FIP.


Reversal of the Progression of Fatal Coronavirus Infection in Cats by a Broad-Spectrum Coronavirus Protease Inhibitor.

Kim Y, Liu H, Galasiti Kankanamalage AC, Weerasekara S, Hua DH, Groutas WC, Chang KO, Pedersen NC - PLoS Pathog. (2016)

Antiviral treatment of symptomatic cats with FIP.(A) In two independent studies, cats were inoculated with FIPV at day 0 and GC376 treatment was started after they developed lymphopenia and clinical symptoms. In the 2nd study, cats received supportive treatment for five days (shaded boxes), which was discontinued prior to antiviral treatment. The arrows and forward slashes indicate antiviral treatment duration and euthanasia, respectively. dpi, days post infection. (B-D) Responses of cats with FIP to antiviral treatment: body temperature (B), percent body weight changes (C) and lymphocyte counts (D) over time. The shaded areas indicate the normal range of values. Colored arrows located between panels B and D indicate the treatment duration for each cat.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4814111&req=5

ppat.1005531.g003: Antiviral treatment of symptomatic cats with FIP.(A) In two independent studies, cats were inoculated with FIPV at day 0 and GC376 treatment was started after they developed lymphopenia and clinical symptoms. In the 2nd study, cats received supportive treatment for five days (shaded boxes), which was discontinued prior to antiviral treatment. The arrows and forward slashes indicate antiviral treatment duration and euthanasia, respectively. dpi, days post infection. (B-D) Responses of cats with FIP to antiviral treatment: body temperature (B), percent body weight changes (C) and lymphocyte counts (D) over time. The shaded areas indicate the normal range of values. Colored arrows located between panels B and D indicate the treatment duration for each cat.
Mentions: To investigate the efficacy of GC376, we conducted two independent studies. In these studies, antiviral treatment was started after the infected cats developed the typical laboratory finding of absolute lymphopenia and clinical symptoms to determine whether treatment with GC376 is effective in reducing the severity of symptoms or fatality. In both studies, the infected cats were monitored daily for fever, body weight, and outward disease signs and weekly for lymphocyte counts. In the first efficacy study, four SPF cats of 8–10 months of age (P02, P03, P07 and P10) were intraperitoneally administrated with a cat-passaged serotype I FIPV (FIPV-m3c-2) [12, 17, 34]. Following infection, they developed lymphopenia and clinical symptoms including inapparent or mild ascites within 14–20 days post infection (dpi) (Table 1). In the second study, the ascites of four SPF cats of 8–10 months of age inoculated with the same virus (P15, P16, P17 and P24) were allowed to progress to more profound, classical abdominal effusions, which closely resemble those of cats with naturally-occurring FIP frequently presented at the clinics (Table 1). However, in order to alleviate suffering, the latter four cats were given meloxicam, a non-steroidal anti-inflammatory drug, and subcutaneous fluids prior to antiviral treatment. This supportive treatment was discontinued before antiviral drug treatment commenced. The eight cats from both studies developed jaundice, inapparent to profound ascites, absolute lymphopenia (134~676/μl, reference range 1,200 to 8,000/μl) and high fever (up to 41.1°C) (Fig 3B and 3D, Table 1) before antiviral treatment was started. They also lost body weight up to 13.6% of their pre-infection weight during this same period (Fig 3C). When they reached this stage, twice daily s.c. administration of GC376 at 5–10 mg/kg/dose was started. These cats were treated for 14–20 days, except for P15 and P16 that were euthanized after 4 and 7 days after starting antiviral treatment based on the severe nature of their clinical signs (Fig 3A). All six remaining cats showed rapid improvement in attitude and resolution of fever (Fig 3B). The profound absolute lymphopenia observed in all cats prior to antiviral treatment also returned to normal before the next blood testing one week later (Fig 3D) and weight losses were reversed and normal growth resumed (Fig 3C). Ascites and scrotal swelling indicative of peritonitis also gradually resolved after a week of antiviral treatment. All cats that received antiviral treatment for 14–20 days appeared normal by clinical observation and laboratory testing. The six recovered cats from both studies have remained healthy showing no signs of relapse during an observation period up to 8 months. These experiments demonstrate that the protease inhibitor was able to reverse disease progression when treatment was initiated at advanced clinical stages of FIP.

Bottom Line: The increasing risks of highly virulent coronavirus infections in humans or animals call for effective antiviral drugs, but no such measures are yet available.Experimental FIP is 100% fatal once certain clinical and laboratory signs become apparent.These results indicate that continuous virus replication is required for progression of immune-mediated inflammatory disease of FIP.

View Article: PubMed Central - PubMed

Affiliation: Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America.

ABSTRACT
Coronaviruses infect animals and humans causing a wide range of diseases. The diversity of coronaviruses in many mammalian species is contributed by relatively high mutation and recombination rates during replication. This dynamic nature of coronaviruses may facilitate cross-species transmission and shifts in tissue or cell tropism in a host, resulting in substantial change in virulence. Feline enteric coronavirus (FECV) causes inapparent or mild enteritis in cats, but a highly fatal disease, called feline infectious peritonitis (FIP), can arise through mutation of FECV to FIP virus (FIPV). The pathogenesis of FIP is intimately associated with immune responses and involves depletion of T cells, features shared by some other coronaviruses like Severe Acute Respiratory Syndrome Coronavirus. The increasing risks of highly virulent coronavirus infections in humans or animals call for effective antiviral drugs, but no such measures are yet available. Previously, we have reported the inhibitors that target 3C-like protease (3CLpro) with broad-spectrum activity against important human and animal coronaviruses. Here, we evaluated the therapeutic efficacy of our 3CLpro inhibitor in laboratory cats with FIP. Experimental FIP is 100% fatal once certain clinical and laboratory signs become apparent. We found that antiviral treatment led to full recovery of cats when treatment was started at a stage of disease that would be otherwise fatal if left untreated. Antiviral treatment was associated with a rapid improvement in fever, ascites, lymphopenia and gross signs of illness and cats returned to normal health within 20 days or less of treatment. Significant reduction in viral titers was also observed in cats. These results indicate that continuous virus replication is required for progression of immune-mediated inflammatory disease of FIP. These findings may provide important insights into devising therapeutic strategies and selection of antiviral compounds for further development for important coronaviruses in animals and humans.

Show MeSH
Related in: MedlinePlus