Not so bad after all: retroviruses and long terminal repeat retrotransposons as a source of new genes in vertebrates.

Viruses and transposable elements, once considered as purely junk and selfish sequences, have repeatedly been used as a source of novel protein-coding genes during the evolution of most eukaryotic lineages, a phenomenon called 'molecular domestication'. This is exemplified perfectly in mammals and other vertebrates, where many genes derived from long terminal repeat (LTR) retroelements (retroviruses and LTR retrotransposons) have been identified through comparative genomics and functional analyses. In particular, genes derived from gag structural protein and envelope (env) genes, as well as from the integrase-coding and protease-coding sequences, have been identified in humans and other vertebrates. Retroelement-derived genes are involved in many important biological processes including placenta formation, cognitive functions in the brain and immunity against retroelements, as well as in cell proliferation, apoptosis and cancer. These observations support an important role of retroelement-derived genes in the evolution and diversification of the vertebrate lineage.

The Hymenoptera venom study. III: Safety of venom immunotherapy.

One thousand four hundred ten (44%) of the 3236 subjects in the Hymenoptera venom study accepted venom immunotherapy (VIT). Time to maintenance averaged 95 days, and the largest number achieved maintenance (147 subjects, 10.4%) at day 56. Ninety-two percent of the treated subjects achieved maintenance, and 84% continued therapy, most subjects (91%) until the study was terminated. One hundred seventy-one subjects (12%) experienced 327 treatment systemic reactions (Srs). The incidence of pruritus and angioedema/urticaria was similar with mild, moderate, or severe SRs. The SR severity did not correlate with the severity of the most recent sting before entry into the Hymenoptera-venom study, the most severe historical sting SR, the most severe SR during venom skin tests, the total dose of venom, the degree of skin test reactivity, or the lowest concentration yielding a positive skin test. Most SRs occurred between 1 and 50 micrograms and at maintenance; honeybee or wasp venoms were most likely to produce SR. This study, the largest of its kind with the use of standardized extracts, demonstrates (1) that there was good compliance, (2) that various historical and diagnostic criteria did not predict SRs to VIT, (3) that SRs to VIT were most likely to occur between 1 and 50 micrograms and at maintenance, (4) that honeybee or wasp venoms were most likely to produce an SR, and (5) that VIT is relatively safe.

The Hymenoptera venom study. II: Skin test results and safety of venom skin testing.

Data are summarized in this Hymenoptera venom study (HVS) article on the safety of skin testing with venom extracts. Of the 3236 subjects studied, 89% had experienced an historical sting systemic reaction (SSR). Seventy-four percent of all subjects and 76% of subjects who had experienced an historical SSR had a positive skin test to at least one venom. More subjects tested positive to yellow jacket venom (51.8%) than to any other venom. There were no significant differences of the wheal and erythema sizes associated with different venoms or different historical sting reactions. Forty-five percent of subjects with positive venom skin tests (VST) were positive to wasp, and 89% of these subjects were also positive to at least one of the following venoms: yellow jacket, yellow hornet, or white-faced hornet. Sixty-four of the 3236 subjects studied (2%) had a systemic reaction (SR) during VST; 13 of the SRs (0.4%) were severe. Thirteen of 64 adverse reactions (20%) were possibly vasovagal, and six other subjects (9%) demonstrated no symptoms of immediate-type hypersensitivity. Thus, 45 (1.4%) of the 3236 subjects tested had an SR that was considered to be a reaction of hypersensitivity, of which eight reactions (0.25%) were severe. Allergic SRs are associated with VST but are unusual and are rarely severe.

The Hymenoptera venom study I, 1979-1982: demographics and history-sting data.

The Hymenoptera venom study, a study based on case histories, skin test results and adverse reactions, immunotherapy and adverse reactions, and treatment efficacy, for 3236 Hymenoptera-allergic subjects, was begun in 1979 after the Food and Drug Administration approval of Hymenoptera venoms. Eighty-four Fellows and Members of the American Academy of Allergy and Immunology participated in the study. All subjects had a history of an adverse reaction to one or more Hymenoptera insects. The mean age was 30 1/2 years (range 1 to 83 years). Male subjects accounted for 61.5% and female subjects, 38.5%; 3.1% were beekeepers and 32.3% were atopic. Demographic data were similar for subgroups. There was an average of 2.7 history stings per subject. At least one systemic reaction (SR) was reported by 2866 subjects (89%); 2219 (69%) experienced an SR after their most recent sting before entry into the study, and 70% had experienced only a single SR. Moderate to severe SRs were equally likely after stings of yellow jacket, white-faced hornet, and yellow hornet (65%), honeybee (67%), or wasp (70%), although historical SRs were reported more often after stings of yellow jacket, white-faced hornet, or yellow hornet (30%) than after honeybee (19%) or wasp (14%) stings. No association was noted between the number of stings per episode and severity of the SR. Fifty-one percent of SRs were reported as occurring within 10 minutes of sting; however, the onset of a moderate to severe SR sometimes occurred at 301 or more minutes after a sting episode. Of 2219 subjects with an SR after their most recent sting before entry into the study, 68% received epinephrine for treatment.