COVID-19 is a new respiratory illness caused by SARS-CoV-2, and has constituted a global public health emergency. Cat is susceptible to SARS-CoV-2. However, the prevalence of SARS-CoV-2 in cats remains largely unknown. Here, we investigated the infection of SARS-CoV-2 in cats during COVID-19 outbreak in Wuhan by serological detection methods. A cohort of serum samples were collected from cats in Wuhan, including 102 sampled after COVID-19 outbreak, and 39 prior to the outbreak. Fifteen sera collected after the outbreak were positive for the receptor binding domain (RBD) of SARS-CoV-2 by indirect enzyme linked immunosorbent assay (ELISA). Among them, 11 had SARS-CoV-2 neutralizing antibodies with a titer ranging from 1/20 to 1/1080. No serological cross-reactivity was detected between SARS-CoV-2 and type I or II feline infectious peritonitis virus (FIPV). In addition, we continuously monitored serum antibody dynamics of two positive cats every 10 days over 130 days. Their serum antibodies reached the peak at 10 days after first sampling, and declined to the limit of detection within 110 days. Our data demonstrated that SARS-CoV-2 has infected cats in Wuhan during the outbreak and described serum antibody dynamics in cats, providing an important reference for clinical treatment and prevention of COVID-19.

A total of 233 isolates of Pasteurella multocida were obtained from 2,912 cases of clinical respiratory disease in pigs in China, giving an isolation rate of 8.0%. Serogroup A P. multocida isolates were isolated from 92 cases (39.5%), and serogroup D isolates were isolated from 128 cases (54.9%); 12 isolates (5.2%) were untypeable. P. multocida was the fourth most frequent pathogenic bacterium recovered from the respiratory tract, after Streptococcus suis, Haemophilus parasuis, and Escherichia coli. All isolates were characterized for their susceptibilities to 20 antibiotics and the presence of 19 genes for virulence factors (VFs). The frequency of antimicrobial resistance among P. multocida isolates from swine in China was higher than that reported among P. multocida isolates from swine in from other countries, and 93.1% of the isolates showed multiple-drug resistance. There was a progressive increase in the rate of multiresistance to more than seven antibiotics, from 16.2% in 2003 to 62.8% in 2007. The resistance profiles suggested that cephalosporins, florfenicol, and fluoroquinolones were the drugs most likely to be active against P. multocida. Use of PCR showed that colonization factors (ptfA, fimA, and hsf-2), iron acquisition factors, sialidases (nanH), and outer membrane proteins occurred in most porcine strains. The VFs pfhA, tadD, toxA, and pmHAS were each present in <50% of strains. The various VFs exhibited distinctive associations with serogroups: concentrated in serogroup A, concentrated in serogroup D, or occurring jointly in serogroups A and D. These findings provide novel insights into the epidemiological characteristics of porcine P. multocida isolates and suggest that the potential threat of such multiresistant bacteria in food-producing animals should not be neglected.

Porcine epidemic diarrhea virus (PEDV),

Sequence-specific DNA-binding transcription factors have widespread biological significance in the regulation of gene expression. However, in lower prokaryotes and eukaryotic metazoans, it is usually difficult to find transcription regulatory factors that recognize specific target promoters. To address this, we have developed in this study a new bacterial one-hybrid reporter vector system that provides a convenient and rapid strategy to determine the specific interaction between target DNA sequences and their transcription factors. Using this system, we have successfully determined the DNA-binding specificity of the transcription regulator Rv3133c to a previously reported promoter region of the gene Rv2031 in Mycobacterium tuberculosis. In addition, we have tested more than 20 promoter regions of M. tuberculosis genes using this approach to determine if they interact with ;150 putative regulatory proteins. A variety of transcription factors are found to participate in the regulation of stress response and fatty acid metabolism, both of which comprise the core of in vivo-induced genes when M. tuberculosis invades macrophages. Interestingly, among the many new discovered potential transcription factors, the WhiB-like transcriptional factor WhiB3 was identified for the first time to bind with the promoter sequences of most in vivo-induced genes. Therefore, this study offers important data in the dissection of the transcription regulations in M. tuberculosis, and the strategy should be applicable in the study of DNA-binding factors in a wide range of biological organisms.

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