Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Recombinant dna technique included in method of making a...
Reexamination Certificate
1999-10-26
2003-11-18
Navarro, Mark (Department: 1645)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Recombinant dna technique included in method of making a...
C435S252300, C435S320100, C435S325000, C536S023700
Reexamination Certificate
active
06649370
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to Chlamydia antigens and corresponding DNA molecules, which can be used in methods to prevent and treat disease caused by Chlamydia infection in mammals, such as humans.
BACKGROUND OF THE INVENTION
Chlamydiae are prokaryotes. They exhibit morphologic and structural similarities to Gram negative bacteria including a trilaminar outer membrane, which contains lipopolysaccharide and several membrane proteins. Chlamydiae are differentiated from other bacteria by their morphology and by a unique developmental cycle. They are obligate intracellular parasites with a unique biphasic life cycle consisting of a metabolically inactive but infectious extracellular stage and a replicating but non-infectious intracellular stage. The replicative stage of the life-cycle takes place within a membrane-bound inclusion which sequesters the bacteria away from the cytoplasm of the infected host cell.
Because chlamydiae are small and multiply only within susceptible cells they were long thought to be viruses. However, they have many characteristics in common with other bacteria: (1) they contain both DNA and RNA, (2) they divide by binary fission, (3) their cell envelopes resemble those of other Gram-negative bacteria, (4) they contain ribosomes similar to those of other bacteria, and (5) they are susceptible to various antibiotics. Chlamydiae can be seen in the light microscope, and the genome is about one-third the size of the
Escherichia coli
genome.
Many different strains of chlamydiae have been isolated from birds, man, and other mammals, and these strains can be distinguished on the basis of host range, virulence, pathogenesis, and antigenic composition. There is strong homology of DNA within each species, but surprisingly little between species, suggesting long-standing evolutionary separation.
C. trachomatis
has a high degree of host specificity, being almost completely limited to man; it causes ocular and genitourinary infections of widely varying severity. In contrast,
C. psittaci
strains are rare in man but are found in a wide range of birds and also in wild, domestic, and laboratory mammals, where they multiply in cells of many organs.
C. pneumoniae
is a common human pathogen, originally described as the TWAR strain of
C. psittaci
, but subsequently recognized to be a new species.
C. pneumoniae
is antigenically, genetically, and morphologically distinct from other Chlamydia species (
C. trachomatis, C. pecorum
and
C. psittaci
). It shows 10% or less DNA sequence homology with either of
C. trachomatis
or
C. psittaci
and so far appears to consist of only a single strain, TWAR.
C. pneumoniae
is a common cause of community acquired pneumonia, less frequent only than
Streptococcus pneumoniae
and
Mycoplasma pneumoniae
. Grayston et al.,
J. Infect. Dis
. 168: 1231 (1995); Campos et al.,
Invest. Ophthalmol. Vis. Sci
. 36: 1477 (1995), each incorporated herein by reference. It can also cause upper respiratory tract symptoms and disease, including bronchitis and sinusitis. See, e.g., Grayston et al.,
J. Infect. Dis
. 168: 1231 (1995); Campos et al.,
Invest. Ophthalmol. Vis. Sci
. 36: 1477 (1995); Grayston et al.,
J. Infect. Dis
. 161: 618 (1990); Marrie,
Clin. Infect. Dis
. 18: 501 (1993). The great majority of the adult population (over 60%) has antibodies to
C. pneumoniae
(Wang et al.,
Chlamydial Infections
, Cambridge University Press, Cambridge, p. 329 (1986)), indicating past infection which was unrecognized or asymptomatic.
C. pneumoniae
infection usually presents as an acute respiratory disease (i.e., cough, sore throat, hoarseness, and fever; abnormal chest sounds on auscultation). For most patients, the cough persists for 2 to 6 weeks, and recovery is slow. In approximately 10% of these cases, upper respiratory tract infection is followed by bronchitis or pneumonia. Furthermore, during a
C. pneumoniae
epidemic, subsequent co-infection with pneumococcus has been noted in about half of these pneumonia patients, particularly in the infirm and the elderly. As noted above, there is more and more evidence that
C. pneumoniae
infection is also linked to diseases other than respiratory infections.
The reservoir for the organism is presumably people. In contrast to
C. psittaci
infections, there is no known bird or animal reservoir. Transmission has not been clearly defined. It may result from direct contact with secretions, from formites, or from airborne spread. There is a long incubation period, which may last for many months. Based on analysis of epidemics,
C. pneumoniae
appears to spread slowly through a population (case-to-case interval averaging 30 days) because infected persons are inefficient transmitters of the organism. Susceptibility to
C. pneumoniae
is universal. Reinfections occur during adulthood, following the primary infection as a child.
C. pneumoniae
appears to be an endemic disease throughout the world, noteworthy for superimposed intervals of increased incidence (epidemics) that persist for 2 to 3 years.
C. trachomatis
infection does not confer cross-immunity to
C. pneumoniae
. Infections are easily treated with oral antibiotics, tetracycline or erythromycin (2 g/day, for at least 10 to 14 days). A recently developed drug, azithromycin, is highly effective as a single-dose therapy against chlamydial infections.
In most instances,
C. pneumoniae
infection is mild and without complications, and up to 90% of infections are subacute or unrecognized. Among children in industrialized countries, infections have been thought to be rare up to the age of five years, although a recent study has reported that many children in this age group show PCR evidence of infection despite being seronegative, and estimates a prevalence of 17-19% in 2-4 years old. See, Normann et al.,
Acta Paediatrica
, 87: 23-27 (1998). In developing countries, the seroprevalence of
C. pneumoniae
antibodies among young children is elevated, and there are suspicions that
C. pneumoniae
may be an important cause of acute lower respiratory tract disease and mortality for infants and children in tropical regions of the world.
From seroprevalence studies and studies of local epidemics, the initial
C. pneumoniae
infection usually happens between the ages of 5 and 20 years. In the USA, for example, there are estimated to be 30,000 cases of childhood pneumonia each year caused by
C. pneumoniae
. Infections may cluster among groups of children or young adults (e.g., school pupils or military conscripts).
C. pneumoniae
causes 10 to 25% of community-acquired lower respiratory tract infections (as reported from Sweden, Italy, Finland, and the USA). During an epidemic,
C. pneumonia
infection may account for 50 to 60% of the cases of pneumonia. During these periods, also, more episodes of mixed infections with
S. pneumoniae
have been reported.
Reinfection during adulthood is common; the clinical presentation tends to be milder. Based on population seroprevalence studies, there tends to be increased exposure with age, which is particularly evident among men. Some investigators have speculated that a persistent, asymptomatic
C. pneumoniae
infection state is common.
In adults of middle age or older,
C. pneumoniae
infection may progress to chronic bronchitis and sinusitis. A study in the USA revealed that the incidence of pneumonia caused by
C. pneumoniae
in persons younger than 60 years is 1 case per 1,000 persons per year; but in the elderly, the disease incidence rose three-fold.
C. pneumoniae
infection rarely leads to hospitalization, except in patients with an underlying illness.
Of considerable importance is the association of atherosclerosis and
C. pneumoniae
infection. There are several epidemiological studies showing a correlation of previous infections with
C. pneumoniae
and heart attacks, coronary artery and carotid artery disease. See, Saikku et al.,
Lancet
2: 983 (1988); Thom et al.,
JAMA
268: 68 (1992); Linnanmaki et al.,
Circulation
87: 1030 (1993); Saikku et al.,
Annals Int. Med
. 116: 273 (1
Dunn Pamela L.
Murdin Andrew D.
Oomen Raymond P.
Aventis Pasteur Limited
Elrifi Ivor R.
Mintz Levin Cohn Ferris Glovsky and Popeo P.C.
Navarro Mark
Triano, III Nicholas P.
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