Search

Simple Summary: In order to understand the prevalence of respiratory diseases in urban stray cats in Shanghai and provide scientific evidence for the development of targeted prevention and control strategies for respiratory diseases in stray cats, we performed a molecular survey in Shanghai in 2022. A total of 374 stray cats were screened against six respiratory pathogens. Out of the 374 samples, 146 tested positive. Mycoplasma felis exhibited the highest positivity rate at 18.72% (70/374), followed by Chlamydia felis at 11.76% (44/374), feline calicivirus at 3.74% (14/374), feline herpesvirus type-1 at 3.48% (13/374), and Bordetella bronchiseptica at 1.34% (5/374); influenza A virus was not detected. Mycoplasma felis and Chlamydia felis were the primary causative agents of respiratory infections in urban stray cats, with Mycoplasma felis demonstrating a notably higher positivity rate compared to other respiratory pathogens and frequently co-infecting with Chlamydia felis and feline calicivirus. The positivity rate of Mycoplasma felis was elevated during the summer, autumn, and winter seasons, with no significant variance between seasons. These results highlight a substantial overall prevalence of respiratory pathogens in urban stray cats in the Shanghai region, characterized by seasonal patterns and concurrent infections with other pathogens. These findings suggest the need for comprehensive prevention and control measures to address respiratory pathogen infections in urban stray cats in the Shanghai area. Urban stray cats are cats without owners that survive in the wild for extended periods of time. They are one of the most common stray animals in cities, and as such, monitoring the pathogens carried by urban stray cats is an important component of urban epidemiological surveillance. In order to understand the prevalence of respiratory diseases in urban stray cats in Shanghai and provide scientific evidence for the development of targeted prevention and control strategies for respiratory diseases in stray cats, we collected 374 ocular, nasal, and oropharyngeal swabs from urban stray cats in Shanghai from January 2022 to December 2022. After RNA extraction, we used real-time PCR to detect six respiratory pathogens, including influenza A virus, feline calicivirus, feline herpesvirus type 1, Mycoplasma, Chlamydia, and Bordetella bronchiseptica. The results showed that among the 374 samples, 146 tested positive, with a positivity rate of 39.04%. The highest positivity rate was observed for Mycoplasma felis at 18.72% (70/374), followed by Chlamydia felis at 11.76% (44/374), feline calicivirus at 3.74% (14/374), feline herpesvirus 1 at 3.48% (13/374), Bordetella bronchiseptica at 1.34% (5/374), and influenza A virus was not detected. The highest positivity rate for Mycoplasma felis was in Minhang District at 31.94% (23/72), while Chlamydia felis and Bordetella bronchiseptica had the highest positivity rates in Jiading District at 23.53% (8/34) and 5.88% (2/34), respectively. The highest positivity rates for feline calicivirus and feline herpesvirus 1 were both observed in Qingpu District, at 14.46% (12/83) and 9.64% (8/83), respectively. A total of 36 samples showed mixed infections with two or more pathogens, with Mycoplasma felis being involved in 32 of these mixed infections, with the highest number of mixed infections being with Chlamydia felis at 25 samples. Respiratory pathogen positivity was detected throughout the year, with peak detection rates in summer and winter. The positivity rates of cat respiratory pathogens in different seasons showed statistical differences (χ2 = 27.73, p < 0.01). There was no statistical difference in the positivity rates of respiratory pathogens between cats of different genders (χ2 = 0.92, p > 0.05). The positivity rates of respiratory pathogens in cats of different age groups showed statistical differences (χ2 = 44.41, p < 0.01). Mycoplasma felis and Chlamydia felis were the main pathogens causing respiratory infections in stray cats, with Mycoplasma felis showing a much higher positivity rate than other respiratory pathogens and often co-infecting with Chlamydia felis and feline calicivirus. The positivity rate of Mycoplasma felis was high in summer, autumn, and winter, with no statistical difference between seasons. These results indicate a serious overall prevalence of respiratory pathogens in urban stray cats in the Shanghai area, showing seasonal trends and mixed infections with other pathogens. These findings suggest the need for comprehensive prevention and control measures to address respiratory pathogen infections in urban stray cats in the Shanghai area. [ABSTRACT FROM AUTHOR]

H9N2 influenza viruses have been circulating in China since 1994, but a systematic investigation of H9N2 in Shanghai has not previously been undertaken. Here, using 14 viruses we isolated from poultry and pigs in Shanghai during 2002 and 2006-2014, together with the commercial vaccine A/chicken/Shanghai/F/1998 (Ck/SH/F/98), we analyzed the evolution of H9N2 influenza viruses in Shanghai and showed that all 14 isolates originated from Ck/SH/F/98 antigenically. We evaluated the immune protection efficiency of the vaccine. Our findings demonstrate that H9N2 viruses in Shanghai have undergone extensive reassortment. Various genotypes emerged in 2002, 2006 and 2007, while during 2009-2014 only one genotype was found. Four antigenic groups, A-D, could be identified among the 14 isolates and a variety of antigenically distinct H9N2-virus-derived avian influenza viruses (AIVs) circulated simultaneously in Shanghai during this period. Challenge experiments using vaccinated chickens indicated that the vaccine prevented shedding of antigenic group A and B viruses, but not those of the more recent groups C and D. Genetic analysis showed that compared to the vaccine strain, representative viruses of antigenic groups C and D possess greater numbers of amino acid substitutions in the hemagglutinin (HA) protein than viruses in antigenic groups A and B. Many of these substitutions are located in antigenic sites. Our results indicate that the persistence of H9N2 AIV in China might be due to incomplete vaccine protection and that the avian influenza vaccine should be regularly evaluated and updated to maintain optimal protection. [ABSTRACT FROM AUTHOR]

The AGA Indices method and weaver indices method are typical overseas interchangeability discriminant methods. Under the background of interchangeability of multi-source natural gas in Shanghai, the pipeline gas in lab is used as reference gas, the AGA Indices (IL, IF, IY) and Weaver Indices (JH, JA, JF, JL, JI, JY) of all kinds of substitute gas were calculated. The interchangeability of reference gas and substitute gas was analyzed theoretically and experimentally. Finally, compared tests with the calculation results, analyzed and discussed the domestic applicability of two indices methods. The tests proved AGA Indices method could well predicted interchangeability but did not give the emission index of CO, while Weaver Indices could well predict flame-out, backfire and heat load change but did not accurately reflect yellow flame and CO emission. Therefore, in order to reflect completely the results of interchangeability by pure index methods, it is necessary to analyze the interchangeability combining domestic reality with two indices methods. Nowadays experiment is still an essential way for identifying interchangeability. And gas interchangeability should not be confused with gas classification. [ABSTRACT FROM AUTHOR]