Sylvia ^orin (2), and Sylvia hcrtensls (2). Five of these plasmas in a 
neutralization test demonstrated complete protection or significant pro¬ 
longation of survival time when compared to comparable HI negative control 
plasmas. 
Tete group . HI results for Bahig (EgB90) and Matruh (EgAnl047-61) are 
presented together (Table 12) since several individuals reacted with both 
of these related viruses and the evidence presented here indicates that these 
are two members of a group of viruses and that perhaps some of the antibody 
is to other viruses of the group as yet not characterized. 
Positive reactions were seen with Falco tinnunculus (1), Emberiza 
hortulana (2), Emberiza caesia (1), Emberiza calandra (1), Phylloscopus 
trochilus (1), Sylvia communis (1), Sylvia curruca (4), Sylvia nisoria (14), 
Sylvia borin (4), Sylvia hortensis (1), Turdus philomelos (1), Erithacus 
rubecula (1), Luscinia megarhynchos (2). The predominance in the genus Sylvia 
is evident. 
All but 3 of these HI reactive plasmas were tested by neutralization test 
with Bahig or Matruh viruses using HI negative plasmas of corresponding species 
(where available) as controls. Fifteen of 31 test plasmas had prolonged aver¬ 
age survival time (over 5 days) whereas only 2 of 31 controls showed comparable 
prolongation. Complete protection was rare but correlated with high HI titer. 
Either the HI test is more sensitive than the neutralization test or the HI 
reactions represent heterologous antibody. It is doubtful that the HI reactions 
could be nonspecific in view of the genus ( Sylvia ) specificity and the correla¬ 
tion between HI antibody and demonstrated natural viremia in this genus. 
Negative isolation attempts from tick pools. Ticks from 424 birds were 
inoculated in baby mice as 221 pools. No pathogens were established from these 
ticks. 
73 
