Donald M. McLean

Characterization of the Immune Response to Trivalent Influenza Vaccine in Elderly Men

This study characterizes the time course of the immune response to influenza vaccine in elderly men. Sixty‐two men aged 58 to 91 years (mean, 74.3 years) were vaccinated with trivalent inactivated influenza vaccine in the fall of 1983. Serum hemagglutinin‐inhibiting (HAI) antibody titers were measured at various times up to 24 weeks postvaccination. Seroconversion frequencies determined at single times after vaccination were 28 to 46% of subjects, whereas cumulative seroconversion frequencies were greater than or equal to 70%. Eighteen to 28% of seroconversions occurred later than four weeks, and greater than or equal to 68% of those who seroconverted experienced greater than four‐fold declines in peak HAI antibody titers by 24 weeks after vaccination. Consequently, 31 to 73% of subjects had HAI antibody titers greater than 40 throughout the study period. Measurement of HAI antibody titers at only one time after vaccination may not adequately reflect the immune response of this population or the degree of protection maintained through the influenza season.

Unusual esophageal ulcers containing enveloped viruslike particles in homosexual men

Eight homosexual men presented with odynophagia. Five had a maculopapular rash and 2 had oral ulcers. Upper panendoscopy revealed the presence of multiple discrete ulcers measuring 3 mm-1.5 cm in diameter in the esophagus of each patient. The intervening mucosa appeared normal. Endoscopic brushings and biopsy specimens taken from the ulcer margins and examined by light microscopy showed no inclusion bodies or giant cells. Fungal stains were negative. Biopsy specimens examined by electron microscopy revealed enveloped virus-like particles 100-140 nm in diameter, exhibiting morphologic features consistent with retroviruses. No virus was isolated after incubation in either rhesus monkey kidney or human foreskin fibroblast culture. Serology for cytomegalovirus and herpes simplex virus was consistent with past infection. In each patient the esophageal ulcers healed completely. In summary, an illness characterized by the presence of esophageal ulcers is described in 8 homosexual men, 5 of whom also had a skin rash and 2 of whom had oral ulcers. The cause of the esophageal ulcers is likely to be the enveloped viruslike particles observed at electron microscopy.

Bunyavirus isolations from mosquitoes in the western Canadian Arctic.

Strains of California encephalitis virus (snowshoe hare subtype) were isolated from 8 of 475 pools comprising 23 747 unengorged female mosquitoes of five species collected at three of six locations throughout the Mackenzie Valley of the Northwest Territories, Canada, from latitudes 60 to 69 degrees N between 10 and 24 July 1976. Minimum field infection rates included 1:2734 for Aedes communis, 1:256 to 1:3662 for A. hexodontus and 1:911 to 1:1611 for A. punctor. Northway virus was also isolated from 1 of 3662 A. hexodontus mosquitoes collected at Inuvik (69 degrees N, 135 degrees W). Transmission of CE virus by A. communis infected by feeding on virus in defibrinated blood and incubation at 0, 13 and 23 degrees C for 13-20 days clearly demonstrates the importance of this species as a natural vector, and transmission of CE virus by Culiseta inornata after incubation at 0 and 13 degrees C following intrathoracic injection strengthens evidence of its role as a natural vector. Immunofluorescence was less reliable than imunoperoxidase for detection of CE viral antigen in mosquito salivary glands.

Transmission of Northway and St. Louis encephalitis viruses by arctic mosquitoes.

SummaryTransmission of a Canadian arctic isolate of Northway virus has been demonstrated after incubation of arcticAedes communis mosquitoes at 13° C for 27 days after intrathoracic injection of 300 plaque forming units of virus. Replication has also been demonstrated after intrathoracic injection of domesticA. aegypti mosquitoes of this virus. Virions of Northway virus, 84–92 nm diameter were morphologically typical of a bunyavirus after propagation in salivary glands ofA. communis or in tissue cultures of baby hamster kidney (BHK-21) cells. An Ontario isolate of St. Louis encephalitis was transmitted by bites ofA. communis after 27 days incubation at 13° C after oral ingestion of 3 or 30 mouse LD50 virus. This mosquito species transmitted virus after 13 to 76 days incubation at 13° C following intrathoracic injection of 3 mouse LD50 or higher virus doses.

California encephalitis virus transmission by arctic and domestic mosquitoes

SummaryA zero passage arctic mosquito isolate of California encephalitis (CE) virus (showshoe hare subtype) was transmitted by wild-caughtAedes communis mosquitoes after 13 days incubation at 13° and 23° C, after 20 days incubation at 13° C, when mosquitoes imbibed 1 mouse LD50 in a blood meal. Transmission occurred after 20 days incubation at 13° and 23° C when mosquitoes were injected intrathoracically with 1 or 0.1 mouse LD50. Virus was also transmitted byA. aegypti 13 days after infection with 100 mouse LD50 by feeding or intrathoracic injection, and incubation at 13° C. Virus antigen was detected in salivary glands of 42 per cent virus-positiveA. communis mosquitoes by direct immunofluorescence, and in 50 per cent or less ofA. aegypti mosquitoes by immunoperoxidase and immunofluorescence, with somewhat greater regularity by the indirect than the direct technique.

California encephalitis virus endemicity in the Yukon Territory, 1972

Sera from 218 of 1574 (14%) small mammals collected in the Yukon Territory between 14 May and 13 August 1972 neutralized a Yukon strain of California encephalitis virus (snowshoe-hare subtype). These included 133 of 319 (42%) snowshoe hares (Lepus americanus), 84 of 1243 (7%) ground squirrels (Citellus undulatus) and 1 of 12 (8%) tree squirrels (Tamiasciurus hudsonicus). California encephalitis virus (snow-shoe hare subtype) was isolated from four pools of unengorged Aedes communis mosquitoes collected near Whitehorse (61 degrees N., 135 degrees W.) and on one occasion each from pools of the same species collected at Hunker Creek (64 degrees N., 138 degrees W.) and at mile 125, Dempster Highway (66 degrees N., 138 degrees W.) during July 1972. Replication of a Yukon strain of California encephalitis virus was observed in wild-caught Culiseta inornata and Aedes canadensis mosquitoes after intrathoracic injection and holding at temperatures of 80 degrees , 50 degrees and 40 degrees F.

Bunyavirus development in arctic andAedes aegypti mosquitoes as revealed by glucose oxidase staining and immunofluorescence

SummaryNorthway virus replication has been detected in salivary glands of wild-caughtCuliseta inornata andAedes communis mosquitoes from the western Canadian Arctic after incubation at 4° C for 9 to 11 months, and after incubation at 13° C for 3 to 4 months after they received virus by oral ingestion or intrathoracic injection.Aedes hexodontus supported Northway virus replication after incubation at 13° C for one month after intrathoracic injection.Aedes aegypti supported Northway virus replication after incubation at 13° C or 23° C for 6 to 28 days following intrathoracic injection. A larval isolate of California encephalitis virus (snowshoe hare subtype) multiplied in all 3 species of arctic mosquito after incubation at 13° C for 1 to 3 months after virus was administered by oral ingestion or intrathoracic injection. Virus was detected in salivary glands ofCs. inornata after 329 days incubation at 4° C after intrathoracic injection. Bunyavirus antigens in salivary glands of arctic and domestic mosquitoes were detected by the glucose oxidase immunoenzyme technique somewhat less frequently than by assay for virus infectivity.