HOMOLOGOUS PROTECTION BUT LACK OF HETEROLOGOUS-PROTECTION BY VARIOUS SPECIES AND TYPES OF BARTONELLA IN SPECIFIC PATHOGEN-FREE CATS

Cat-scratch disease (CSD) is caused by Bartonella henselae, and possib ly by B. clarridgeiae. In immune-compromised persons, B, henselae is o ne of the agents causing bacillary angiomatosis. Domestic cats are the main reservoir of these bacteria, which are transmitted primarily fro m cat to cat by fleas, Possible strategies to prevent the spread of in fection among cats are to eliminate flea infestation or to prophylacti cally immunize cats. In order to develop an appropriate vaccine, it is important to determine if cats become resistant to re-infection by th e same strain or various types or species of Bartonella. In a series o f experiments, 21 SPF cats were experimentally infected by the intrade rmal route with 10(5)-10(10) colony-forming units/ml of either B. hens elae type II (17 cats), or a new strain 'Humboldt' isolated from a mou ntain lion (4 cats). The cats were bled weekly to every other week for determination of bacteremia and specific antibody production, After t hey cleared their infection, they were challenged by a homologous or h eterologous strain of Bartonella: 10 cats were challenged with B. hens elae type II, three cats with B, henselae type I, four cats with B. cl arridgeiae and four cats with the 'Humboldt' strain. Seven of these ca ts received a third inoculum dose resulting in three cats sequentially infected with sequence B. henselae type II/ B. henselae type II/ 'Hum boldt', two cats with sequence B. henselae type II/ 'Humboldt'/B. clar ridgeiae, and two cats with the sequence 'Humboldt'/B, henselae type I I/'Humboldt'. All cats challenged with a homologous strain remained ab acteremic after challenge and had an increased IBG antibody titer. All cats challenged with either a different Bartonella species or type be came bacteremic. The few cats receiving a third inoculum with a strain homologous to the initial strain remained abacteremic after that chal lenge. All cats infected with B. clarridgeiae suffered relapsing bacte remia compared to only 36% of the B. henselae infected cats and 22% of the 'Humboldt'-infected cats (p=0.008). The duration of bacteremia wa s significantly longer in B. henselae primary-infected cats (mean: 34 weeks) than B. henselae heterologously challenged cats (mean: 9 weeks) (p=0.014). These data clearly indicate the lack of cross-protection b etween B. henselae and B. clarridgeiae and furthermore, indicate the l ack of protection between B. henselae types I and II, and a wildlife i solate. A vaccine strategy for CSD prevention in domestic cats will re quire a multivalent vaccine approach. (C) 1998 Elsevier Science B.V. A ll rights reserved.