John T. May

Antimicrobial factors and microbial contaminants in human milk: Recent studies

An overview of recent studies of antimicrobial factors and microbial contaminants found in human milk is presented. The incidence of gastrointestinal and respiratory infections in infants receiving human milk continues to be lower than in those not breast‐fed due to the presence of specific antibody and possibly anti‐adhesion factors in the milk. Whether the many other antimicrobial factors, which have been shown to be active in vitro or in animal model systems, have any influence on infant infections is still not clear. Microbial contaminants in human milk are rare, as are associated infant infections from the milk. However, some contaminants such as cytomegalovirus are commonly transferred to infants from the milk of seropositive mothers, fortunately without any adverse effects in the infants. Human T‐lymphotropic virus type 1 is transferred via human milk in endemic areas, human milk being the main source of mother‐to‐infant transmission. While some reports suggest human immunodeficiency virus type 1 transfer may occur through human milk, this is not the predominant mode of transmission to infants.

Antimicrobial properties and microbial contaminants of breast milk — an update

Abstract A review of recent studies of antibacterial, antiviral and antiprotozoan factors in human breast milk is presented. Also reviewed are the microbial contaminants that have been detected in human milk with a particular focus on cytomegalovirus and rubella virus, both of which have recently been shown to infect infants via breast milk.

Location and Characterization of the Bovine Herpesvirus Type 2 Thymidine Kinase Gene

The precise genomic location and the nucleotide sequence of the bovine herpesvirus type 2 (bovine herpes mammillitis virus) thymidine kinase (TK) gene have been determined. The genomic location of the TK gene was found to be in a similar position to that of herpes simplex virus. The coding region consists of 918 bases, which is slightly smaller in length than other reported herpesvirus TK genes. However with an Mr of 38,108 the individual protein is similar in size to other herpesvirus TK enzymes. Despite there being only limited overall sequence homology with the TK genes of other herpesviruses, there are several regions of extensive homology at the amino acid level.

Human lymphoblastoid cell lines established from peripheral blood lymphocytes secreting immunoglobulins directed against herpes simplex virus.

Peripheral blood lymphocytes (PBL) from genital herpes simplex virus type 2 (HSV-2) patients were transformed with Epstein-Barr virus. Using conditions optimized for successful transformation, two lymphoblastoid cell lines (LCL) have been established, which secrete immunoglobulin G (IgG) to HSV. These results suggest that PBL from patients suffering recurrent herpes virus infections can be used to establish LCL secreting HSV antigen specific human immunoglobulins.

Confirmation of herpes simplex virus type 2 infections in herpes-like genital lesions by a simple complement-fixation test.

The presence of complement-fixing antibody to an early herpes simplex virus type 2 (HSV-2) antigen (the AG-4 antigen) was correlated with HSV-2 infection in the sera of patients with genital herpes. Eighty-eight per cent of sera taken two weeks after clinical diagnosis of a primary or recurrent herpes infection in patients, confirmed to have HSV-2 by virus isolation and typing, contained the anti-AG-4 complement-fixing antibody. None of the patients with genital HSV-1 had the antibody, and only 9% of controls or patients with facial HSV-1 infection had positive results for the antibody. This correlation was used to identify genital HSV-2 infections when either no virus sample had been taken or when virus isolations had been unsuccessful. Thus, a simple complement-fixation test can confirm an HSV-2 virus infection without isolation of the virus from the herpetic lesion.

Analysis of the HSV-2 early AG-4 antigen

SummaryGenital herpes simplex virus type 2 (HSV-2) infections can be distinguished from present or past HSV-1 infections by an AG-4 antigen complement fixation assay. The assay which utilizes a 4 hour HSV-2 infected cell extract prepared at a multiplicity of infection (MOI) of 1.0 PFU/cell, appears to consist of several viral proteins. Studies using monoclonal antibodies, polyclonal rabbit hyperimmune serum, HSV-1×HSV-2 intertypic recombinant viruses and polyacrylamide gel electrophoresis suggest that ICP8 may be one of the major antigens involved in the complement fixing reaction. It is probable that the success of the assay is not due to a true type specificity but rather a threshold phenomenon in which HSV-2 extracts contain more early viral antigens (including ICP8) and sera from HSV-2 patients contain more complement fixing antibody to these antigens.

Modification of the Genital Herpes Infection in a Guinea Pig Model, by Prior Immunization with Bovine Herpes Mammillitis Virus

Bovine herpes mammillitis virus has been shown to partially protect guinea pigs against primary genital herpes simplex virus type 2 infections, further confirming the immunologic cross‐reactivity of these two viruses.

Expression of the herpes simplex virus type-2 major DNA-binding protein (ICP8) gene in COS-1 cells

By the use of an SV40 origin of replication plasmid vector and the COS-1 cell system, expression of the gene encoding the herpes simplex virus type-2 (HSV-2) major DNA binding protein (ICP8) has been achieved. The HSV-2 4.5 kb BglII 0 DNA fragment containing the ICP8 coding region was inserted into the plasmid vector pSVOd containing the SV40 origin of replication. Transfection of COS-1 cells by the resultant recombinant plasmid (pSVOd20), and subsequent multiplication of this plasmid, led to the production of the HSV-2 major DNA binding protein in sufficient quantities to allow its detection with either monoclonal or polyclonal antibodies as well as sera taken from HSV-2 patients.

Unusual serologic response to two patients to an early antigen of herpes simplex virus type 2.

Two patients infected with herpes simplex virus type 2 (HSV-2) who were free of recurrences over a 13-14-month period had an unusually high titer (greater than 1:48) of complement-fixing antibody to the early antigen (AG-4) of HSV-2. Their response was also unusual in that it was an IgG complement-fixing antibody rather than IgM, which normally is found in patients with HSV-2 infection. The antibody was also present 13-14 months after the episode of HSV-2 disease, whereas in other patients, the response had declined by six months.