Matumoto et al. (1959) reported isolation of an adenovirus, which was neutralized not only by adenovirus type 3 antiserum but also by adenovirus type 7 antiserum, from a fatal case of infantile pneumonia. They suggested that this kind of adenovirus type might be produced by hybridization between adenovirus types 3 and 7. It remains to be studied that such a suggestion may hold true, and a reversed view may also be possible to consider, namely the adenovirus type possessing the combined antigenic patterns of types 3 and 7 may be an original or ancestral one and adenovirus types 3 and 7 may be derived from it. No matter which hypothesis holds true, as is well understood, the combined type of virus has a fewer chance of persistence in an at least partially immune population than the virus of single-antigenic pattern, because the infection of the former is prevented by both of the two antibodies, while that of the latter only by an antibody corresponding to its antigenic type. In such a respect, it may be of some importance to get information of an actual epidemiologic feature of the combined type adenovirus.
There is another problem concerning the infection of adenovirus of the combined antigenic pattern. (The term “adenovirus 3, 7” will be employed for the combined adenovirus type now in question for convenience of description hereafter in this publication.) As is well recognized, the adenovirus infection shows various manifestations of the clinical and epidemiological feature which depend in some way upon the type of the adenovirus responsible for the infection in question. Sporadic cases of pharyngoconjunctival fever are sometimes found to be caused by adenovirus types other than type 3 or 7 (Fukumi et al., 1957 a, b ; Huebner et al., 1957; Merchant et al., 1958), while epidemic outbreaks of pharyngoconjunctival fever are exclusively caused either by type 3 or by type 7 of adenovirus, at least in Japan. The case, from whom Matumoto et al. (1958) described to have isolated adenovirus 3, 7, fell ill first with a symptom of bronchitis and then died of bronchopneumonia.He was not described to have had any sign of conjunctival affection, but it was reported that his sister (5 years of age) had follicular conjunctivitis with fever, conjunctival edema and corneal infiltration several days prior to the onset of the disease in the patient in question and was treated under the diagnosis of epidemic keratoconjunctivitis (Osada and Hanayama, 1958) . It is very likely that the infant obtained his fatal illness from his sister, who must have been suffering from acute pharyngoconjunctival fever, and thus it is suggested that the adenovirus 3, 7 might be able to cause pharyngoconjunctival fever. Furthermore, Osada and Hanayama (1958) suggest as an epidemiological background of the reported case an epidemic of an illness, which may have been diagnosed as primary atypical pneumonia, and at the same time an epidemic of allegedly epidemic keratoconjunctivitis which was very possibly considered to be pharyngoconjunctival fever. Thus it may be of importance to know what kind of clinical feature this type of adenovirus infection develops in general.
Recently we had two chances of isolating the adenovirus 3, 7 from cases of pharyngoconjunctival fever, and the present publication is devoted to describe the details thereof.
