MATERIALS AND METHODS

Duration of the study: This study has been conducted during the period between January, 2016 and April, 2018.

Ethical approval and informed consent: The owners of cats were informed and permission was received from them. The cat included in this study for taking samples used in this work. Samples were collected as per standard sample collection procedure without any harm to animals. The proposal of this study had approval from National Research Center comity No: 10/1/2016.

Examined animals: About 300 Persian cats of different age and sex were investigated in this study. They were received at German vet clinic at 6th October city, Giza, Egypt, cats were suffering from clinical signs suggestive for FPV infection. These animals were classified into different age groups and sex, Table 1.

Table 1:	Numbers, age and sex of the examined cats

Clinical examination: The received diseased cats were subjected to a clinical examination according to the method described by Awad et al.¹ and Gaskell et al.³.

Fecal samples were collected from all of 300 diseased cats and were examined by Snap test rapid antigen test using kits obtained from Bionote Inc. Korea. This was used for qualitative detection of viral antigen in feces^1,3.

Clinical determination of dehydration rate was done according to DiBartola and Bateman¹¹, Brown and Otto¹² and Mensack¹³, Chan¹⁴.

Blood samples: Blood samples from some cases of dehydration rate less than 7% were collected and examined according to Duncan et al.⁸.

Treatment trail: All of the diseased cats (n = 300) received the following treatment:

Statistical analysis: Statistical analysis was applied on the results to detect if there was any effect of the age and sex between different groups using chi-square test according to Smith¹⁸. All statements of significance were based on probability of p<0.05.

RESULTS

Clinical examination: Clinical changes in the form of lethargy, fever, vomiting, diarrhea and dehydration were observed in different rates and severity among the diseased cats Table 2 illustrated the distribution, rate and severity of these clinical changes in different age and sex groups in the three treated groups. The results revealed that the clinical changes of lethargy and anorexia were considered as severe in cats with 3-10 months old and were moderate with 12-24 months old. Vomiting and Diarrhea were considered as severe in cats with 6-7 months old. Most of clinical changes were between mild and moderate in cats with 12-24 months old.

ELISA: All of the examined male and female cats were positive to ELISA test.

White blood cells counts: Representative samples of blood collected from disease cats were examined to detect panleukopenia as mentioned in Table 3. The recorded values of total WBCs in examined blood samples indicated the sharp leucopenia in relation to dehydration rate. The dehydration rate ranged between 5-6% and the white blood cells counts ranged between 1.9×10⁹ to 2.0×10⁹/L.

Clinical improvement: In group 1 (treated with Feliserin): The improvement has begun in the 3rd day and increased till the 5th day post isolation and treatment. In addition, 85 cats were survived while 15 died (Table 4). In group 2 (treated with Zylexis): The improvement has started in the 4th day and increased till day 6 post isolation and treatment. Moreover, 16 cats survived and 84 cats died (Table 4). In group 3 (that received fluids therapy, anti emetic and antibacterial agents only): The improvement has begun in the 4th day and increased till 7th day post isolation and treatment. In this group only 7 cats were survived (Table 4).

Additionally, the improvement was manifested in different groups by decrease in body temperature at the 3rd day post treatment in group 1 (treated with Feliserine) and at 4th day in group 2 (treated with Zylexis). Regarding vomiting the results found that the vomiting time began to decrease on day 2 and stopped on day 4 in group 1, while the vomiting time began to decrease on day 3 and stopped on day 5 in group 2, however, vomiting time was stopped at the 6th day in group 3 (received fluids therapy, anti emetic and antibacterial agent). Furthermore, time of diarrhea began to decrease at the 2nd day and stopped at the 4th day in group 1, while it began to decrease at the 3rd day and stopped at the 5th in group 2, however, it stopped at the 6th day in group 3.

Statistical analysis: As Fig. 1 showed the comparison of drugs effect used for treatment of Feline panleukopenia virus infection (FPV) in cats in relation to age in months. The results exhibited that number of survived cats (male and females) at the 2 age intervals of 6-7 and 8-10 month old was increased significantly (p<0.05) in the group treated with Feliserine compared with those in group treated with Zylexis (Fig. 1).

Table 2:	Clinical changes detected in different age and sex groups in the 300 diseased cats
Lethargy (attitude): Normal(-)-mild(+)-moderate(++)-sever(+++) ( severe depression), Anorexia: Normal apetit(-)-mild (+)-moderate(++)-sever(+++) (no appetite), Vomiting: Mild(+) (once per 12 h), Moderate (++) (2-5 times per 12 h), Sever (+++) (>6 times per 12 h), Diarrhea: Normal faeces(-), Mild (soft or pasty) (+), moderate (watery diarrhea) (++), Sever (watery and bloody) (+++)

Moreover, at the 2 age intervals of 12 and 24 month old males and females in group treated with Feliserine revealed significant recovery (p<0.05) more than group treated with Zylexis and group received fluids therapy, anti emetic and antibacterial agent. However, at the 2 age intervals of 12 and 24 month old males and females there is no significant differences in recovery rate (p>0.05) between group treated with Zylexis and group received fluids therapy, anti emetic and antibacterial agent (Fig. 1).

Fig. 1:	Comparison of drugs effect used for treatment of feline panleukopenia virus infection (FPV) in cats in relation to age
	a,bNumbers with different letters, within treatment, differ significantly (p<0.05)

Table 3:	White blood cells counts in relation to dehydration rate in examined cats
*Normal WBCs count is 5.5-15.4×109/L, WBC: White blood cells

DISCUSSION

The acute form of FPV is the most common which began with non-specific general signs such as pyrexia, depression, vomiting commonly occurs and not related to eating.

In the late stage of the disease cats develop watery to hemorrhagic diarrhea. Majority of infected cats showed severe dehydration in addition to anorexia, vomiting and diarrhea, this may lead to progressive depression and weakness, infected cats die from complications associated with dehydration and septicaemia^1,3,9,19. These findings were detected in current study as 100% of the diseased cats have dehydration with different degrees while 64.6% having hemorrhagic enteritis.

Treatment of Feline panleukopenia infection with use of Fel IFN- and the use of IgG antibodies have not been conducted in cats either experimentally or therapeutically in hospitals on a large scale⁹, to the best of our knowledge.

The use of zylexis^® was tried in present treatment plan to study its impact as a treatment for diseased cats.

In the first group: the use of specific neutralizing antibodies (consisting of IgM (+), IgG (++), IgA (+)) against FPV was applied in this study according to Tizard²⁰ . Current study showed that a good prognosis and recovery was present in form of 85% survival rate and detected clinically by stopping vomiting, subsiding of fever, decrease diarrhea and reduce anemia^1,9,20.

The effective role of neutralizing antibodies against FPV virons in viraemic stage was excellent in diminishing viraemia rapidly, then reduce destructive effect of FP viral replication in lymphoid tissue, bone marrow, circulating WB cells,^2,9,21-23.

Table 4:	Numbers of survived cats in the three treated groups

This role was achieved by different mechanisms via antibody mediated immunity. Neutralizing antibodies prevent cell invasion by blocking the adsorption of virons to target cells and stimulating phagocytosis of viruses. Neutralizing antibodies kill infected cells by complement mediated cytolysis or by antibody dependent cell mediated cytotoxicity.

The use of neutralizing antibodies proved to be more efficient through antibody mediated destruction of infected cells^9,20,24.

In the second group, use of recommended dose of lophalized Parapox ovis virus strain D1701 as a precursor for generation of 230 IFN units was tried^9,20,21.

Survival rate in FPV infected cats of this group (group 2) was 16%^9,18,25.

IFN includes three fractions as IFN-α, IFN-β, IFN-γ, IFN-γ binding to receptors of target cells creating resistance to virus infection within few minutes to 5 h, also IFN-γ induce production of certain synthase enzyme result in preventing virus growth in interferon activated macrophages. IFN α, β play important role on activation of certain enzymatic reaction lead to inhibition of viral growth as concluded by Tizard²⁰, Liu et al.²⁶ and Kang et al.²⁷.

In the third group that received supportive treatment, the survival rate was 7% and recovered cats were in the age group of 1 year and more. Trepanier¹⁶ stated that FPV is one of main causes of immune suppression in cats that is the reason for using antibiotic therapy in diseased cats⁹.

However, statistical analysis were conducted using Chi-square revealed that both males and females' cats of age groups 6-7, 8-10, 12 and 24 months in group treated with Feliserin PLUS revealed significant recovery rate (p<0.05) more than in group treated with Zylexis. While there is no significant difference in recovery rate (p>0.05) between group treated with zylexis and group. Served as control group for 12 month, 24 month old males and females.

CONCLUSION

Use of feline specific neutralizing antibodies against FPV was proven to be more efficient in treatment of Feline panleukopenia infection in cats with survival rate of 85% in comparison to the use of lyophilized inactivated Parapox ovis virus strain D1701 as a source for production of IFN with survival rate of 16%. While the use of fluid therapy and supportive treatment in the 3rd group gave a recovery rate of 7% in diseased cats.

SIGNIFICANCE STATEMENT

This study discovers the effective treatment for Feline panleukopenia virus infection that can be beneficial for decreasing mortalities among infected cats significantly. This study will help the researchers to uncover the critical areas of failure of treatment trials that many researchers were not able to explore. Thus, a new FPV effective treatment regimen may be arrived at. Our results recommend the use of specific neutralizing anti-bodies against FPV than the use of inactivated parapox ovis strain D1701 in treatment of Feline panleukopenia virus infection in cats.

ACKNOWLEDGMENTS

The authors are grateful to Prof. Dr. Sobhy Abd-Elshafy, at Parasitology and Animal Diseases Department, Veterinary Division, National Research Center, Giza, Egypt, for providing the technical and scientific consultant regarding statistical analysis of data. Present study received no financial support.