Fig. 6.

Haematuria and acute renal insufficiency (measured by serum creatinine) in immunized C3HeB and BALB/c mice. By direct microscopic examination of the urinary sediment, haematuria was detected in nearly all immunized C3HeB or BALB/c mice by 2 days after intranasal challenge with infectious virus, but not in syngeneic immunized controls not challenged intranasally (* denotes χ² = 7·1, P < 0·01 versus syngeneic controls) or challenged with inactivated (non-infectious) virions (data not shown). Intranasal challenge of naive mice with infectious virus did not elicit haematuria in either strain (not shown), despite high levels of virus in nasal washings (see Table 1). Most (≥ 72%) immunized BALB/c mice challenged with infectious virus, but none of the BALB/c controls, had elevated serum creatinine levels, indicative of acute renal insufficiency (* denotes χ² = 5·7, P < 0·02 compared to all the BALB/c control groups). Mice of the C3HeB strain rarely (< 17%) exhibited evidence of acute renal insufficiency, even if immunized and challenged with infectious virus (‡ denotes χ² = 5·7, P < 0·02 between strains in the same treatment group). , C3HeB; □, BALB/c.