|   | 
|  Complement-fixation test. An antiserum for Eyach with a homologous titer of 32 was tested against antigens for 49 non-group B tick-borne viruses; the serum reacted only with Colorado tick fever (CTF) antigen, with a titer of 16.   | 
|  In another test, 15 polyvalent grouping sera or ascitic fluids were tested against an antigen for Eyach; only the fluid containing CTF antibodies reacted with Eyach.   | 
|  The CF relationship between CTF and Eyach is as follows:   | 
|   | 
|       Antigen       |       Serum       | 
|---|
 |   |       Eyach       |       CTF       | 
|---|
 
  |  
  |  |        Serum titer/antigen titer        |  |       Eyach       |       128/128       |       64/64       |  |       CTF       |       32/64       |       256/512       |  
  | 
|  Neutralization tests: In newborn mice, by intracerebral route ofinoculation.   | 
|   | 
|       Serum       |       Virus       | 
|---|
 |   |       Eyach       |       CTF       | 
|---|
 
  |  
  |  | a        LNI expressed in dex        |  |       Eyach       | 3.3  a |       0.3       |  |       CTF       |       2.9       |       4.0       |  |       Normal       |  |  
  | 
|   |