Within the gp41 glycoprotein of the human immunodeficiency virus type 1 (HIV-1) there is a relatively conserved region which appears accessible to the immune system during the course of HIV infection and is recognised by antibody from virtually all patients with AIDS. This region has also been shown to function as a target for human T cells. We have examined synthetic peptides spanning this sequence, between residues 572 and 604, with a view to evaluating their potential as immunogens. Peptides572GIKQLQARILAVERYLKDQQ591 and579RILAVERYLKDQQLLGGIWGCSGK601 were good immunogens in two different strains of mice while peptide576LQARILAVERYLKDQQ591 was an inferior immunogen, and peptide593LGIWGCSGKLIC604 was non-immunogenic unless coupled to a carrier protein. For both antibody and T cell responses it was apparent that sequences that could function as determinants within one peptide could not do so in the context of a different peptide immunogen. It follows that by judicious choice of immunogen sequence it may be possible to direct the immune response towards a desired fine specificity. Unwanted responses by CD4+ T cells isolated from certain peptide-primed animals were also observed. These T cells showed an unusual reactivity in that they were incapable of recognising their determinant AVERYLKDQQ if it was extended at the C-terminal end with the native sequence and as such would not be expected to recognise the native molecule unless processing created the identical C-terminus.

Monoclonal antibodies (MAbs) specific for the hemagglutinin (HA) of the H3 subtype of influenza A virus were grouped according to their inability to bind to particular MAb-selected neutralization escape mutants of the virus having an amino acid substitution in one of the five postulated antigenic sites on the molecule. Additional residues critical to the binding of the MAbs were deduced from their patterns of reactivity with a panel of field strains and receptor mutants of the H3 subtype. The relationship of these residues to the actual epitopes recognized by the MAbs was inferred from their location on the three-dimensional structure of the HA molecule. In this way it was generally possible to identify a number of residues that are critical to the integrity of the epitope recognized by each of the MAbs examined. It was found that: (1) Several of these epitopes appear to be discontinuous and some may depend on residues contributed by more than one monomer. For example, residue 205, in the interface between monomers of the HA, was found to affect the integrity of the epitopes for several MAbs, possibly by stabilizing the conformation of residues around the receptor-binding pocket and/or in site B on the adjacent monomer. The activity of these particular MAbs was greatly decreased if the virus was exposed to pH 5. (2) All the MAbs tested neutralized viral infectivity and inhibited hemagglutination, although the single MAb directed to site C, which is the most distant from the receptor-binding site, was the least efficient. (3) Hemagglutination inhibition, and particularly neutralization tests, were more discriminating than ELISA in discerning subtle differences between the corresponding epitopes recognized by MAbs on different field strains. (4) Efficiency of neutralization of infectivity did not correlate consistently with hemagglutination inhibiting efficiency; MAbs postulated to bind to epitopes close to the receptor-binding pocket were very efficient at inhibiting hemagglutination, whereas neutralization efficiency tended to be more influenced by the affinity of binding of the MAb. (5) A MAb binding to any particular epitope could affect the binding of a second MAb directed to an epitope within the same or even a different antigenic site. The observed effect was most commonly inhibition of binding, which was not always reciprocal; enhancement of binding was also observed with certain combinations of MAbs. The relative affinity of the MAbs, in addition to steric constraints, were shown to be important factors in the ability to compete for interaction with HA.

A total of 14 I-Ad-restricted helper T-cell clones specific for the hemagglutinin (HA) molecule of influenza virus were isolated from spleens of BALB/c or (BALB/c X C57BL/10)F1 mice immunized with the H3 subtype influenza virus A/Memphis/71 (Mem 71) and from lymph nodes of BALB/c mice primed with purified HA. The specificity of these T-cell clones was assessed in proliferation assays by reactivity with naturally occurring strains of viruses that arose by antigenic drift and contain known amino acid sequence changes in HA and with a panel of monoclonal antibody (MAb)-selected mutants of Mem 71 with single amino acid substitutions in HA. The HA genes of those mutant viruses that failed to stimulate one or more of the T-cell clones were sequenced. The clones could be allocated to at least four groups, each group having a distinct pattern of reactivity with the panel of natural field strains. The epitopes recognized by the four groups of clones were found, by reactivity with MAb-selected mutants, to be in very close proximity to one another and probably overlapping. All of the distinct epitopes recognized by the T-cell clones were adversely affected by a single amino acid substitution, either at residue 60 or at residue 63 in the HA1 polypeptide chain, within the region known from antibody-binding studies as site E. Some, but not all, of the epitopes may be influenced by the addition of a carbohydrate side chain to the HA of a particular MAb-selected mutant and certain field strains containing an Asp----Asn substitution at residue 63. Site E is therefore a major site of H-2d helper T-cell recognition on the H3 HA.

Progress in antiviral chemotherapy has taken place as a logical strategy for the design of antiviral agents has emerged. The second-generation nucleoside analogues, led by acyclovir, have proved their worth against herpesviruses and should now become a standard part of medical practice. Meanwhile, recombinant DNA technology has lowered the cost of interferons to the point at which the several human subtypes of these naturally occurring hormones can be subjected individually to controlled clinical trials against the viral diseases in the treatment of which they show promise. Yet, optimism about the future of antiviral chemotherapy must be tempered by the observation that most of the agents discussed in this review are described more accurately as promising rather than proven, and several of these have not yet been released in Australia at the time of writing.

The oligosaccharide sidechains attached to the major polypeptide, HA1 of the haemagglutinin of influenza virus were examined for antigenic activity using a solid-phase radioimmunoassay. Cross-reactivity between the HA1 of the different human subtypes was clearly demonstrable with IgG raised against purified virus but was abrogated if anti-carbohydrate antibodies were first removed by passage of the IgG through an immunoadsorbent column containing haemagglutinin (HA) from an unrelated avian influenza strain. Antibodies eluted from the column were found to cross-react with the HA1 of all subtypes tested. 'Host antigen' extracted from chick chorioallantoic membrane and coupled to Sepharose was also able to remove cross-reactive antibodies from antiviral sera, while antibodies raised against host antigen bound to the HA1 isolated from each subtype tested. It is concluded that, although there are qualitative and quantitative differences between the oligosaccharide sidechains of influenza haemagglutinins, the antigenically active sidechains are cross-reactive.

All the polypeptide fragments obtained by cyanogen bromide cleavage of the hemagglutinin from A/Memphis/102/72 influenza virus were examined for their ability to bind to IgG raised against purified virus. Within the hemagglutinin heavy chain the only fragment displaying antigenicity is HA1CN1, which comprises the amino-terminal 168 amino acid residues. By the use of a sensitive radioimmunoassay in which the antigen is unlabeled, it was shown that the light chain is also antigenic. Inhibition studies have localized the activity to the HA2CN1 region, which comprises the carboxy-terminal 90 amino acids. The determinant on HA2 is shown to be subtype specific.

In vitro and in vivo assays have been developed to study the relative contributions of various types of immune cytolysis in the destruction of infected cells after Semliki Forest virus infection of BALB/c mice. Highly cytotoxic activated macrophages, not specific for the infecting virus, appear on day 1, peak on day 2 to 3, and disappear within a week. Specifically sensitized T cells appear around day 3, peak on day 6, and disappear within a month. Cytotoxic antibody appears on day 4 and reaches high titers by day 8. Immune spleen cells greatly reduce the yield of virus from cultured cells. Infected cells rapidly disappear after transfer to infected animals.

Post-translational cleavage of the influenza viral glycoprotein HA occurs to different extents in different systems, varying not only for a particular virus strain grown in different host cells, but also for two strains of virus grown in the same host cell. Preparations of virus in which the HA is not substantially cleaved contain hemagglutinating and infectious virions. Cleavage occurs at different sites in the HA molecule of different virus strains.

Medical Journal of AustraliaVolume 2, Issue 2 p. 59-63 Original Article HERPES SIMPLEX VIRUS INFECTION OF THE CORNEA D. O. White M.B., Ph.D., M.C.P.A., D. O. White M.B., Ph.D., M.C.P.A. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalProfessor of Microbiology, University of Melbourne.Search for more papers by this authorM. A Shew, B.Sc., M. A Shew, B.Sc. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalResearch Assistant, National Health and Medical Research Council.Search for more papers by this authorK. G. Howsam M.B., B.S., D.O., F.R.A.C.S., K. G. Howsam M.B., B.S., D.O., F.R.A.C.S. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalMedical Director, The Royal Victorian Eye and Ear Hospital.Search for more papers by this authorI. F. Robertson M.B., B.S., D.O., I. F. Robertson M.B., B.S., D.O. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalAssistant Ophthalmic Surgeon, The Royal Victorian Eye and Ear Hospital.Search for more papers by this author D. O. White M.B., Ph.D., M.C.P.A., D. O. White M.B., Ph.D., M.C.P.A. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalProfessor of Microbiology, University of Melbourne.Search for more papers by this authorM. A Shew, B.Sc., M. A Shew, B.Sc. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalResearch Assistant, National Health and Medical Research Council.Search for more papers by this authorK. G. Howsam M.B., B.S., D.O., F.R.A.C.S., K. G. Howsam M.B., B.S., D.O., F.R.A.C.S. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalMedical Director, The Royal Victorian Eye and Ear Hospital.Search for more papers by this authorI. F. Robertson M.B., B.S., D.O., I. F. Robertson M.B., B.S., D.O. School of Microbiology, University of Melbourne, and The Royal Victorian Eye and Ear HospitalAssistant Ophthalmic Surgeon, The Royal Victorian Eye and Ear Hospital.Search for more papers by this author First published: 01 July 1968 https://doi.org/10.5694/j.1326-5377.1968.tb29290.xCitations: 9 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume2, Issue2July 1968Pages 59-63 RelatedInformation

Medical Journal of AustraliaVolume 2, Issue 6 p. 280-285 The Growing Edge of Medicine VIRUSES AND DISEASE EN MAN David O. White M.B., B.S., Ph.D., M.C.P.A., David O. White M.B., B.S., Ph.D., M.C.P.A. School of Microbiology, University of MelbourneProfessor of Microbiology.Search for more papers by this author David O. White M.B., B.S., Ph.D., M.C.P.A., David O. White M.B., B.S., Ph.D., M.C.P.A. School of Microbiology, University of MelbourneProfessor of Microbiology.Search for more papers by this author First published: 01 August 1968 https://doi.org/10.5694/j.1326-5377.1968.tb29427.xCitations: 3 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume2, Issue6August 1968Pages 280-285 RelatedInformation

Medical Journal of AustraliaVolume 1, Issue 11 p. 447-449 Original Article ADENOVIRUS AND INTUSSUSCEPTION David O. White M.B., B.S., Ph.D., M.C.P.A., David O. White M.B., B.S., Ph.D., M.C.P.A. MelbourneReader in Virology, University of Melbourne. Present address, Department of Cell Biology, Albert Einstein College of Medicine, Eastchester Road and Morris Park Avenue, Bronx. N.Y., U.S.A.Search for more papers by this authorJohn E. Solomon F.R.C.S., F.R.A.C.S., John E. Solomon F.R.C.S., F.R.A.C.S. MelbourneSenior Assistant Surgeon to Out-patients, Royal Children's Hospital, Melbourne.Search for more papers by this author David O. White M.B., B.S., Ph.D., M.C.P.A., David O. White M.B., B.S., Ph.D., M.C.P.A. MelbourneReader in Virology, University of Melbourne. Present address, Department of Cell Biology, Albert Einstein College of Medicine, Eastchester Road and Morris Park Avenue, Bronx. N.Y., U.S.A.Search for more papers by this authorJohn E. Solomon F.R.C.S., F.R.A.C.S., John E. Solomon F.R.C.S., F.R.A.C.S. MelbourneSenior Assistant Surgeon to Out-patients, Royal Children's Hospital, Melbourne.Search for more papers by this author First published: 01 March 1966 https://doi.org/10.5694/j.1326-5377.1966.tb72471.xCitations: 1 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume1, Issue11March 1966Pages 447-449 RelatedInformation

Eggs differ in their susceptibility to infection by influenza virus. This paper reports an investigation of the causes of this variation in suspended fragments of allantois-on-shell.

1. Methods are described for altering the susceptibility of the surviving allantois to infection by influenza viruses.2. Under natural conditions susceptibility is a linear function of age between 10 and 18 days of incubation. The drop is 0·11 log10unit per day for all strains of influenza tested.3. In whole eggs this decline is masked by the effect of acid allantoic fluid which prevents infection when the pH falls below 6. The effect is not directed against the virus particle, nor does it do permanent damage to the cell, as surviving tissues are equally susceptible whatever the pH of the allantoic fluid that bathed themin ovo.4. Surviving membranes can be made less susceptible by incubating the eggs at 35° rather than 38° C.; by maintenance for 24 hr.in vitro; by use of deficient or inappropriate medium. These methods lower susceptibility more for some strains than for others.5. All treatments which lower susceptibility also increase its variation from egg to egg.

The standard tests for infectivity of influenza viruses in eggs or mice have two major shortcomings. First, the host systems are known to be inhomogeneous, i.e. the response does not depend solely on the dose; and second, this variation from host to host cannot be assessed independently, since a single test only can be made on any one egg or mouse. Thus, the two probabilities—the presence of an infective unit in the inoculum and the success of a particular virus-host interaction—are confounded, so that we estimate not the number of infective units but an unknown function of this number. Valid comparisons of infectivity can still be made as long as one is satisfied with a relative answer, and does not wish to inquire into the nature of host-resistance.

It is shown that the assay for infectivity in bits of allantois-on-shell, which has been standardized on the BEL strain, is optimal also for nine representative strains of influenza virus tested. On the average, the sensitivity of the technique is the same as of orthodox allantoic infectivity tests; its precision is always higher. The relative sensitivity of the two tests varies from strain to strain, the log tray/egg differences being SW (+0.88), MEL (+0.51), CAM (+0.31), PR8 (0.28), WSE (+0.25), HUT (−0.02), BEL (−0.22), FMI (−0.35), LEE (−0.47), BON (−1.02). This gradient is the same for fully infective and incomplete forms of influenza virus. The tray/egg gradient of susceptibility is negatively correlated with the variation in host resistance. The differences in susceptibility are not due to any effect of the plastic trays, to thermal inactivation of the virus, to differences in adsorption or viropexis in the two test systems or to the effect of allantoic fluid on the virus particle. The critical step has been shown to occur during the intracellular stage of multiplication.