In silico analyses and design of chimeric proteins containing epitopes of Bartonella henselae antigens for the control of cat scratch disease.

Bartonella henselae is a Gram-negative bacterium that causes cat scratch disease (CSD), as well as bacteremia, endocarditis, and other clinical presentations. CSD remains one of the most common infections caused by bacteria in the genus Bartonella, and it is transmitted to humans through a scratch or cat bite. Vaccination and more efficient diagnostic methods would represent a promising and sustainable alternative measure for CSD control in humans and animals. Here, we described the in silico analyses and design of three recombinant chimeric proteins (rC1, rC2, and rC3), for use in the control of CSD. The chimeras were constructed with epitopes identified from the sequences of the GroEL, 17 kDa, P26, BadA, Pap31, OMP 89, and OMP 43, previously described as the most important B. henselae antigens. The rC1, rC2, and rC3 were expressed and purified using a heterologous system based on Escherichia coli and reacted with antibodies present in the sera of humans naturally infected. The chimeric proteins were used to immunize mice using Freund adjuvant, and the humoral immune response was evaluated. Animals immunized with rC1 and rC3 showed a significant IgG antibodies response from the 28th day (P < 0.05), and the animals immunized with the rC2 from the 35th day (P < 0.05) remained until the 56th day of experimentation, with a titer of 1:3200 (P < 0.05), 1:1600 (P < 0.05) and 1:1600 (P < 0.05) from rC1, rC2, and rC3, respectively. Significant production of IgA and IgG1 isotype was detected in animals immunized with rC1 and rC2 proteins. Additionally, analysis using 13 serum samples from naturally infected patients showed that the proteins are recognized by antibodies present in sera, reinforcing the possibility of using these chimeras for CSD control. KEY POINTS: • The recombinant chimeras were expressed in Escherichia coli with 37 kDa (rC1), 35 kDa (rC2), and 38 kDa (rC3). • Animals immunized with rC1, rC2, and rC3 showed significant antibody response. • The chimeras were recognized by the sera of naturally infected patients.

Survey of Bartonella species in cats from Abruzzo region, Italy.

Cat scratch disease (CSD) is a zoonotic disease, caused predominantly by Bartonella henselae and transmitted to humans through a scratch or bite of the cat. Cat represents the principal reservoir and healthy carrier of Bartonella, which is mainly transmitted, among cats, by the flea Ctenocephalides felis. During 2014, fifty­two samples of whole blood and sera were collected randomly from cats in Abruzzo region and were examined by real-time PCR and IFAT tests, respectively. Seven samples out of fifty­two (13.5%) resulted positive for Bartonella spp. in both tests, while six specimens (11.5%) resulted real-time PCR negative but IgG positive; thirty­nine were instead both real-time PCR and IFAT negative (75%). Sequence analysis of a fragment of DNA identified B. henselae and B. clarridgeiae in four and in two real­time PCR positive samples, respectively.

Feline bartonellosis.

Bartonella infection is common among domestic cats, but the role of Bartonella species as feline pathogens requires further study. Most Bartonella species that infect cats are zoonotic. Cats are the mammalian reservoir and vector for Bartonella henselae, an important zoonotic agent. Cat fleas transmit Bartonella among cats, and cats with fleas are an important source of human B henselae infections. New information about Bartonella as feline pathogens has recently been published, and this article summarizes much of that information. Issues surrounding diagnosis and treatment of feline Bartonella infections are described, and prevention of zoonotic transmission of Bartonella is discussed.

Experimental infection of domestic cats with passaged genotype I Bartonella henselae.

The influence of in vitro passage on Bartonella henselae pathogenesis in cats has not been thoroughly evaluated. Our objective was to examine the bacterial kinetics and humoral immune responses in cats experimentally infected with three different in vitro passages of B. henselae F1, a genotype I strain of feline origin. The F1 strain was in vitro passaged 20 and 40 times, and each was inoculated into a group of 5 cats. The kinetics of bacteremia and the feline humoral immune response to bacterial antigens were compared to a previous study involving a group of six cats inoculated with the original F1 strain. Among the three groups of cats, the kinetics of bacteremia profiles and the humoral immune responses to B. henselae lysates were similar. The influence of passage on bacterial membrane proteins was examined. In vitro passage altered the expression of 4/17 (23.5%) bacterial membrane proteins and 6/15 (40%) bacterial membrane antigens. An association between poor seroreactivity to three lysate antigens (15-, 18- and 45kDa), prolonged bacteremia and decreased serum bactericidal activity was noted. Our data show that in vitro passage of B. henselae did not alter the kinetics of bacteremia, including the occurrence of relapsing bacteremia, in experimentally infected cats. This suggests that highly passaged strains may not be suitable for future vaccination studies. Furthermore, in vitro passage results in phenotypic and antigenic changes in the bacterial membrane protein profile, which warrants caution in the interpretation of studies involving passaged B. henselae strains.

Cat scratch disease. A cause of regional lymphadenitis.

BACKGROUND: In the last decade, the microbiological cause of cat scratch disease (CSD) has been determined using a combination of traditional culture and modern molecular techniques. A bacterium known as Bartonelia henselae is responsible for the vast majority of cases. The natural history of the disease is being reinterpreted in the light of more sophisticated diagnostic tools. OBJECTIVE: To enable practitioners to have a sound basis for the diagnosis and treatment of cat scratch disease. DISCUSSION: Bartonelia henselae is ubiquitous in the domestic feline and causes zoonotic infection in humans. Although this infection is usually self limiting and benign, it may cause more extensive disease in the immunosuppressed. Antibiotic therapy may hasten recovery.

Passive antibody to Bartonella henselae protects against clinical disease following homologous challenge but does not prevent bacteremia in cats.

We challenged cats transfused with anti-Bartonella serum and kittens born to antibody-positive queens with Bartonella henselae to determine the contribution of antibodies to the control of B. henselae in cats. In both experiments, antibody-positive cats were protected from clinical disease but passive antibody to the homologous strain of B. henselae did not prevent bacteremia.

Bartonella henselae infection in cats: evaluation during primary infection, treatment, and rechallenge infection.

Bartonella henselae infection was established in eight cats of various ages by experimental inoculation. All cats remained persistently bacteremic until they were treated 4 to 7 weeks after primary inoculation. Antibody titers increased and peaked between 4 and 12 weeks for all cats. Treatment with doxycycline for 1 week was effective in suppressing bacteremia in all cats but was effective in clearing infection from only four cats. Amoxicillin, given subsequently, was effective in clearing the infection from three of the remaining cats. One kitten that remained bacteremic was treated unsuccessfully with enrofloxacin, and its bacteremia was finally cleared when it was treated with a clavulanate-amoxicillin combination. After the bacteremia was cleared, with a corresponding reduction in serum antibody titers, all eight cats were rechallenged with B. henselae. None of the cats became bacteremic after secondary challenge, and all had higher and more rapid increases in serum antibody titers than after primary inoculation. The cats became resistant to reinfection following recovery from infection, indicating that immunoprophylaxis in cats might be beneficial in helping to reduce their public health risk.

Animal-induced injuries and disease, viral infections, neonatal jaundice, and immunizations.

This review highlights recent advances in four areas of interest to the pediatrician: animal-induced injuries and disease, viral infections, neonatal jaundice, and immunizations. Molecular biology techniques are dramatically impacting our understanding of the pathophysiology of disease states. The application of this "modern medicine" to the bedside is rapidly becoming commonplace. As clinicians we need to understand the opportunities this affords us as well as its potential limitations. The above four areas of concern will be explored with this in mind.

Zoonotic diseases of cats.

As veterinarians, our responsibilities do not end with the care of our patients. The welfare of our clients and their families depends on our ability to detect and control potentially zoonotic diseases in their pets. Because some of these zoonoses can have devastating effects on the development of the unborn fetus or on family health in general, discussion about these diseases between veterinarian and client is often emotionally charged. Under such circumstances, the offering of inaccurate and erroneous information by the veterinarian can have drastic consequences. It is likely that other zoonotic diseases of domestic pets will be identified in the future, especially those that can cause opportunistic infections in debilitated and immunodeficient persons. In the meantime, the potential hazards of cat ownership can be significantly reduced through an increased understanding of feline diseases and an improved level of health care for our feline patients.