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The aim of this study was to develop a novel duplex nested RT-PCR (dnRT-PCR) method which can simultaneously detect and distinguish feline herpesvirus type 1 (FHV-1) and feline calicivirus (FCV) in cats with upper respiratory tract disease (URTD) and evaluate the performance of this assay in clinical screening. Four pairs of primers based on TK gene of FHV-1 and ORF2 gene of FCV were designed, respectively, and a dnRT-PCR assay was developed and evaluated. A total of 115 clinical swaps of cats collected from private veterinary clinics and animal shelters in Jilin province between November 2016 and May 2017 were used to evaluate this newly developed dnRT-PCR method compared with conventional assay. The results indicated that the detection limits of this method were 101.0 TCID50/ml, 102.2 TCID50/ml and 102.0 TCID50/ml for FHV-1, FCV and a mixture of the two viruses which were 100-fold and 1000-fold higher than single and duplex conventional RTPCR/PCR, respectively, and was also highly specific. Clinical screening indicated the concordance rates for dnRT-PCR and single conventional RT-PCR/PCR were 99.13% (kappa=0.955) for FHV-1 and 98.26% (kappa=0.956) for FCV, respectively. These results suggest that the duplex nested RT-PCR is a rapid and sensitive method that is useful for clinical diagnosis and etiological investigation of feline caolicivirus and feline herpesvirus. [ABSTRACT FROM AUTHOR]

Feline calicivirus (FCV), a highly contagious virus, is one of the major causes of upper respiratory infections in domestic cat populations and wild felines. It is a ubiquitous issue around the world, which constantly demands veterinary attention. Vaccination for FCV has generally been proposed as a cure for its infections. However, the high antigenic variability of this virus hinders the development of efficacious FCV vaccines. In this study, the experimental inactivated vaccine was developed with strain FCV CH-JL2 at 108.00 TCID50/mL, 1% binary ethylenimine (BEI) was utilized for inactivation at 37°C for 48 h, then was mixed with aluminum hydroxide which was used as an adjuvant. Through regular observation and monitoring, it was confirmed that the kittens in each group had a good mental state and appetite after the vaccination, and their body temperature was normal. Compared with the control group, the antibody levels increased, and no adverse reactions were seen. Its effects were evaluated using the previously constructed animal infection model to measure clinical symptoms after vaccination and FCV challenging. All kittens were challenged with FCV CH-JL2 at 42 days of post vaccination (dpv). The clinical signs of body weight, body temperature, viral shedding, survival rates were monitored daily during 14 days of post challenge (dpc). It has been shown that serum IgG levels and neutralization titer were significantly higher than the commercial inactivated vaccine, and kittens manifested normal clinical signs, good mental status and appetite after vaccination and subsequent viral challenging, the protection rate is 100% (5/5). Collectively, these preliminary data indicate that inactivated vaccine can provide complete protection against infection caused by the challenge FCV CH-JL2 for kittens, and FCV CHJL2 strain is a promising candidate for developing a safe and effective FCV vaccine in the future. [ABSTRACT FROM AUTHOR]