Immune response of neonatal specific pathogen-free cats to experimental infection with Bartonella henselae

The purpose of this study was to determine whether neonatal cats develop an d maintain a persistent bacteremia for longer than do adult cats with a nor mal mature immune system, and whether neonatal cats are susceptible to infe ction with Bartonella henselae by oral inoculation. Neonatal specific patho gen-free (SPF) cats were inoculated with B. henselae intradermally (n = 4) or orally (n = 5) or with 0.9% NaCl (n = 2). Blood was collected periodical ly through 16 weeks post-inoculation (PI) for serology, bacteriology and co mplete blood count. Cats inoculated orally or intradermally at 3-5 days of age were bacteremic through 12-16 weeks PI, similar to what is documented f or adult cats inoculated intradermally or intravenously. One cat inoculated at age 2 weeks was bacteremic through 10 weeks PI; the other was not bacte remic. Intradermally inoculated neonatal cats produced serum IgG antibodies to B, henselae but orally inoculated neonatal cats did not. Infected cats with and without serum IgG antibodies to B. henselae became blood-culture n egative simultaneously, suggesting that IgG is not required to clear bacter emia. (C) 1999 Elsevier Science B.V. All rights reserved.