Unnatural Host Research Articles

Effects of Physical and Chemical Signals on Host Foraging Behavior of Drino inconspicua (Diptera: Tachinidae), a Generalist Parasitoid

Host-foraging behavior of the tachinid parasitoid, Drino inconspicua Meigen (Diptera: Tachinidae), was studied by laboratory bioassays to elucidate the role of physical and chemical factors for host finding and recognition. Larvae of the European spruce sawfly, Gilpinia hercyniae Hartig (Hymenoptera: Diprionidae), were used as hosts. While volatiles of spruce twigs with feeding sawfly larvae did not attract the parasitoid, movements of host larvae and of dummies of the host significantly elicited a positive response at short range. Females of D. inconspicua showed a direct walking behavior to a moving object at distances of 9-10 cm. The maximum distance at which the parasitoids were attracted by movement was 16 cm. At short range, parasitoid females preferred to contact a moving larval dummy made of filter paper rather than an unmoved dummy or an unmoved freshly killed larva of C hercyniae. The tachinid females which were reared from G. hercyniae larvae showed no preference for this host species when compared with larvae of Diprion pini L. (Hymenoptera: Diprionidae) and the unnatural host species Galleria mellonella L. (Lepidoptera: Pyralidae). Furthermore, D. inconspicua did not prefer certain instars of G. hercyniae for oviposition. The role of cuticular chemicals of C. hercyniae larvae for host acceptance was tested by offering host larvae washed with solvents of different polarities and unwashed larvae, Each tested parasitoid female readily accepted both treated and untreated larvae for oviposition. When a hexane extract of the cuticle of host larvae was applied to a dummy, ovipositing D. inconspicua did not significantly distinguish between a treated dummy and a control dummy. Whereas the parasitoid's response to dummies offered as oviposition sites did not depend on the presence of cuticular extracts of hosts, the softness of the dummies was crucial. The parasitoid females significantly preferred soft dummies (hardiness unit [HU]:0.05± 0.01 Nmm -2 ) to hard ones (HU: 207.72± 6.16 Nmm -2 ) for oviposition. Thus, physical factors like movement of the host and its softness clearly play a major role in host foraging of D. inconspicua rather than chemical signals of the host or its host plant.

The development and persistence of phanerozoites in experimental infections of Plasmodium sasai

Phanerozoites of Plasmodium sasai parasitised virtually all tissues of Takydromus tachydromoides infected by inoculation of blood, and persisted until each lizard died, 2–296 days postinoculation. At 4 days postinoculation, phanerozoites were larger than at 2 and 6 days; many were observed rupturing, suggesting a maturation time of approximately 4 days. The proliferation of phanerozoites decreased after 2 months postinoculation, but small phanerozoites were still present at 296 days. A few encysted phanerozoites (chronozoites) appeared at 2 days postinoculation, but from 75 days comprised over half of parasites present in most tissues. Some differences in mean size and shape were evident among various organs. Phanerozoites occurred in connective tissue and endothelium in all organs, but were most plentiful in the heart in every infection, often occurring in clusters of >30 schizonts, with up to 105 found in single sections at 4 days. Phanerozoites did not parasitise reticular cells of the spleen and bone marrow, in contrast to Plasmodium mexicanum as described in unnatural host species. Little difference was seen between two strains of P. sasai in its natural host T. tachydromoides and a strain isolated from Takydromus smaragdinus.

Mode of action of the venom of the ectoparasitic wasp,Euplectrus comstockii, in causing developmental arrest in the European corn borer,Ostrinia nubilalis

Euplectrus comstockii Howard (Hymenoptera: Eulophidae), is an ectoparasitic, gregarious wasp which parasitizes the larval stage of several important lepidopteran pests. Parasitization of both natural and unnatural hosts prevents molting in the parasitized instar. Here we report the effect of wasp venom on the European corn borer (unnatural host), an important pest of corn and other vegetables. Venom collected from venom glands of adultE. comstockii, when injected intoO. nubilalis 5th instars, inhibited the growth rate, development and molting of the injected larvae. The observed effect on molting was dose and age dependent. When 3rd, 4th and 5th instarO. nubilalis were envenomated by adult wasps, the larvae also were developmentally arrested and failed to undergo a molt. However, 3rd and 4th instars underwent apolysis (separation of the epidermis from the old cuticle) and produced new cuticle. Fifth instars did not. A premolt hemolymph ecdysteroid peak was not observed in these experimental 5th instars, but injections of 20-hydroxy-ecdysone induced apolysis and new cuticle formation. Envenomated 4th instars (on becoming pharate 5th instars) exhibited a premolt hemolymph ecdysteroid peak. HPLC/RIA revealed that 20-hydroxyecdysone was present in the hemolymph of these pharate 5th instars. Thus, in the European corn borer, the mode of action of the venom depended upon the instar parasitized. Our results support the presence of a venom component(s) that, in 4th instar hosts, inhibited ecdysis, but did not prevent hemolymph ecdysteroid levels from increasing sufficiently to stimulate apolysis. In 5th instars, the same, or perhaps, a different component(s) ofE. comstockii venom prevented the synthesis/release of ecdysteroid by inhibiting a previously unknown molt-regulating physiological event that occurs between days 3 and 4 of the instar.

Adaptation of equine herpesvirus 1 to unnatural host led to mutation of the gC resulting in increased susceptibility of the virus to heparin.

Heparin extensively inhibited infection of MDBK cells by equine herpesvirus 1 (EHV-1) strains adapted to bovine cells or hamsters, while the reagent merely reduced infectivity of strains passaged only in equine cells. The gC of two strains adapted to non-equine cells seemed to have higher affinity for heparin, although the reagent bound to both the gC and gB of all strains tested. Amino acid substitutions of the gC of the EHV-1 strains adapted to non-equine cells converged on the hydrophilic regions, amino acid residues 92 to 175, resulting in the glycoprotein becoming more cationic. These results indicate that these hydrophilic regions of the gC may be responsible for binding to heparin.

Characterization of the clinical and anatomical pathological changes associated with Hepatozoon mocassini infections in unnatural reptilian hosts

Laboratory-reared Aedes aegypti mosquitoes were employed in the successful transmission of Hepatozoon mocassini from a cotton-mouth moccasin ( Agkistrodon piscivorus leucostoma) to 3 lizard species ( Sceloporus undulatus, Eumeces obsoletus and Sceloporus poinsetti). Marked to severe lethargy and anorexia developed in the S. undulatus, E. obsoletus and S. poinsetti at 15, 38, and 96 days postinfection (PI), respectively. All 3 lizards developed a leukocytosis and had increased plasma aspartate aminotransferase activity (AST) by 14 days PI. Multifocal random hepatocellular necrosis and intrahepatic aggregates of heterophils centered on mature H. mocassini meronts were demonstrated in all 3 lizards. The pulmonary interstitium was multifocally thickened by aggregates of heterophils centered on meronts. No comparable clinical or anatomical pathological changes were demonstrated in naturally infected snakes. The results of this study suggest that H. mocassini is capable of inducing necrotizing inflammatory lesions in unnatural reptilian hosts.

Demonstration of common and stage-specific anti- Hepatozoon mocassini antibodies in experimentally infected unnatural lizard hosts

This study examines the immunological response to Hepatozoon mocassini in lizards. Three lizard species were infected experimentally with H. mocassini. Baseline and post-infection (PI) sera were assayed for anti- H. mocassini meront and gametocyte antibody by immunohistochemistry and IFA. Seroconversion occurred at 38 d PI with endpoint IFA titers of 1:64. Antisera from non-parasitaemic and parasitaemic lizards exhibited similar affinities for merozite and gametocyte antigens. Antibody specific for the membranes of gametocyte-infected erythrocytes was demonstrated exclusively in parasitaemic lizards. The results demonstrate that lizards infected with snake haemogregarines mount an antibody response with common and stage-specific components.

Potential of an Unnatural Host, Galleria mellonella (Lepidoptera: Galleriidae), in Rearing the Corn Earworm Endoparasitoid Microplitis croceipes (Hymenoptera: Braconidae)

Females of the endoparasitoid Microplitis croceipes (Cresson) oviposited in early 5th instars of an unnatural host, greater wax moth, Galleria mellonella (L.), after they had been treated with hemolymph and frass from the natural host corn earworm, Helicoverpa zea (Boddie). Third-instar H. zea , similar in size to 5th-instar G. mellonella were used for comparison. Forty-one percent of the G. mellonella larvae were accepted for opposition, and 90% of 3rd instars of the natural host. Parasitoid cocoons weighed 8.30 ± 0.34 mg (mean ± SE) compared with 14.08 ± 0.16 mg from H. zea . Adult emergence was 46.9 and 92.6% on G. mellonella and H. zea , respectively. The sex ratio of parasitoids reared on G. mellonella (40% male to 60% female) was not significantly different from parasitoids reared on H. zea (35% male to 65% female). F1 adults reared on G. mellonella were smaller than those reared on H. zea . When the F1 progeny of G. mellonella -reared parents were reared back on the natural host, H. zea , the resultant adult parasitoids were of normal size.

Evaluation of rubella virus E2 and C proteins in protection against rubella virus in a mouse model

An animal model is described that can provide further information for evaluating novel vaccines against rubella virus (RV). A group of mice was immunized with the lysate of insect cells infected by a recombinant baculovirus expressing E2 and C proteins of RV. Another group of mice was immunized with the RA27/3 rubella vaccine. After 2 weeks, both groups of mice were challenged intramuscularly with live RV and the blood was drawn after 8, 24, 48 and 72 h. The presence of rubella challenge virus in unnatural host, such as the mouse, was monitored by RT-PCR. The mice immunized with the RA27/3 rubella vaccine were the only ones able to inhibit the challenge virus replication, E2 and C proteins, which alone are not sufficient to protect animals against RV, served as a negative control for a protective vaccine against RV that expresses E1 protein of RV.

Host selection, location, and association behaviors of anemonefishes in field settlement experiments

Nine anemonefish species were reared in the laboratory, and individuals were released in the field (Lizard Island, Australia and Madang, Papua New Guinea) at different distances and orientations away from natural (anemone species the fishes are found with in nature) and unnatural species of host anemones. Experiments were conducted to examine factors that could affect the settlement behaviors of the fishes: current velocity, distance and orientation of the fishes to the anemones, chemical vs visual cues, and presence of conspecific or heterospecific fishes. The fishes were usually attracted toward natural host species of anemones but not towards unnatural host anemone species nor to pieces of dead coral. Host selection during settlement provided the best explanation for the host specificity patterns displayed by anemonefishes in nature. The fishes used chemical cues released from the anemones to identify and locate the appropriate host species and could effectively locate the anemones from a maximum distance of 8 m downstream. Fishes released upstream or to the side of anemones (where anemone chemicals were assumed to be reduced or absent) were much less successful in locating anemones. The ability of the fishes to locate natural host anemones was strongly reduced when there was no water current. The presence of resident anemonefishes on host species of anemones did not influence the attraction behavior of anemonefishes released downstream from the anemones. Once the released fishes got close to or entered the anemones, the resident fishes would generally bite and chase them until the recruits left the anemones. Most fishes were not stung upon initial contact with the anemones.

Diferenças na resistência adquirida de cães, hamsters e cobaias a infestações repetidas por carrapatos Rhipicephalus sanguineus (Acari:Ixodidae) adultos

Grupos experimentais de cães, hamsters e cobaias sem contato anterior com carrapatos, sofreram três infestações consecutivas por carrapatos Rhipicephalus sanguineus adultos e a resistência adquirida comparada com base na variação de alguns dos parâmetros biológicos da fêmea do carrapato. Os resultados mostraram que hamsters e cobaias principalmente, desenvolvem uma reação imune muito eficiente a esta espécie de carrapato como demonstrado por uma queda altamente significativa na taxa de eficiência da fêmea em converter sua reserva alimentar em ovos e larvas da primeira para as segunda e terceira infestações. Já cães foram incapazes de desenvolver tal resistência. Neste hospedeiro a performance das fêmeas dos carrapatos foi similar durante todas as infestações, havendo até uma tendência de melhora com a sucessão das infestações. Estes resultados reforçam a necessidade de estudos comparativos sobre a resistência adquirida a carrapatos, envolvendo hospedeiros naturais e não naturais, como forma de colocar em evidência mecanismos de defesa que possam estar alterados ou ocultos em relações parasita-hospedeiro naturais.

Host Range Tests with Edhazardia aedis (Microsporida: Culicosporidae) against Northern Nearctic Mosquitoes

Twelve species of northern Nearctic mosquitoes representing five genera (Aedes, Anopheles, Culex, Culiseta, and Psorphora) were bioassayed for susceptibility to Edhazardia aedis, an exotic, heterosporous, microsporidian parasite of the yellow fever mosquito, Aedes aegypti. Infections were achieved in Aedes atropalpus, Aedes triseriatus, and Aedes vexans following oral ingestion of uninucleate spores obtained from patently infected Ae. aegypti larvae. The microsporidium underwent normal vegetative growth and development in each unnatural mosquito host; the only differences observed were in the degree of infection. With the exception of adult oenocytes, the predominant sites of infection in Ae. triseriatus were generally similar to those in Ae. aegypti. These included the gastric caeca and muscle tissue in larvae and fat body tissue in adult females. Binucleate spores, which are normally responsible for ovarian infection and transovarial transmission in Ae. aegypti, were produced in all but one (Ae. atropalpus) susceptible host. However, E. aedis was not transmitted transovarially to larvae of the filial generation by these alternate female hosts thus indicating a high level of specificity for Ae. aegypti. Since E. aedis can not complete its normal life cycle through two successive host generations in alternate host mosquitoes, its potential as a biological control agent would appear to be limited to Ae. aegypti.

Host Specificity of Calyptospora funduli (Apicomplexa: Calyptosporidae) in Atheriniform Fishes

Calyptospora funduli has a broad host specificity, infecting at least 7 natural and 10 additional experimental definitive hosts, all atheriniform fishes within 5 families, but most in the genus Fundulus. Barriers, apparently innate ones, prevent any development of C. funduli in perciform fishes but allow incomplete or abnormal development of the parasite in a few unnatural atheriniform hosts. In the freshwater species Fundulus olivaceus and Fundulus notti, these abnormalities consisted of asynchronous development, degeneration of the parasite in early stages of development, and the formation of numerous macrophage aggregates. Rivulus marmoratus has the ability to eliminate infections with a granulomatous inflammatory response. Additional barriers that limit natural infections of C. funduli in other hosts include feeding behavior, environmental conditions, and geographic isolation.

Life Cycle of Leishmania major (Kinetoplastida: Trypanosomatidae) in the Neotropical Sand Fly Lutzomyia longipalpis (Diptera: Psychodidae)

The development of Leishmania major Yakimoff & Schokhor in the New World sand fly Lutzomyia longipalpis (Lutz & Neiva) was examined by light and electron microscopy. In this unnatural host, parasites differentiated into 10 typical morphological forms, multiplied at three sites, migrated anteriorly and established in the foregut, and attached to gut surfaces. In the blood meal, amastigotes divided and transformed into two successive dividing, stumpy promastigote stages. Elongate nectomonad promastigotes developed from stumpy forms and subsequently rounded up in some flies into paramastigotes and opisthomastigotes. Differentiation into round opisthomastigotes and the apparent fusion of paramastigotes in the blood meal were novel observations in this study. Three nectomonad promastigotes--elongate, short, and metacyclic--were free-swimming in the midgut lumen. Elongate nectomonad promastigotes were highly oriented in the midgut, with their flagella embedded between the epithelial microvilli. Short haptomonad promastigotes were the predominant form attached to the intima of the stomodeal valve, whereas pear-shaped haptomonad promastigotes and paramastigotes colonized surfaces of the esophagus and pharynx. Peripylarian attachment of promastigotes and paramastigotes in the pylorus, ileum, and colon was noted in 21% of flies, suggesting that suprapylarian leishmanias have not lost the ability to colonize the hindgut. L. longipalpis was a successful biological host for L. major, allowing complete development of the parasite.

Viral zoonoses.

Viral zoonoses cause overt disease in humans and other animals or silent infections in animals and overt disease in unnatural hosts such as humans. Often the virus and its animal host have evolved together and learned to live together. Infection may spread freely between the natural host animals and cause no signs of disease, but this balance may be upset by many factors, including stress, changing environmental conditions and mutations in both viruses and hosts. Infection of an unnatural host may cause clinical disease but no further spread of the virus. Examples of viral zoonoses both old and new are used to illustrate some of these points, and two will be described in detail--Rift Valley fever and influenza.

Leishmania differentiation in natural and unnatural sand fly hosts.

Leishmania differentiation in the gut of phlebotomine sand flies was evaluated based on five light and electron microscopic studies of natural (Leishmania panamensis/Lutzomyia gomezi, Leishmania chagasi/Lutzomyia longipalpis) and unnatural (Leishmania mexicana/Lutzomyia abonnenci, Leishmania panamensis/Phlebotomus papatasi, Leishmania major/Lutzomyia longipalpis) life cycles. In the bloodmeal, transformation of amastigotes into stumpy promastigotes occurred before or during division. Further division in pairs or rosettes resulted in the development of spatulate and/or elongate nectomonad (free-swimming) promastigotes. Elongate, short, and metacyclic nectomonad promastigotes, and nectomonad paramastigotes were present in the midgut lumen. Dividing short promastigotes predominated in the cardia, and appeared to generate metacyclic forms which were observed in three life cycles. Haptomonad (attached) forms of Leishmania panamensis in the hindgut were primarily spatulate promastigotes (natural host) or pear-shaped promastigotes (unnatural host); paramastigotes and dividing forms were rare. At the stomodeal valve, short haptomonad promastigotes predominated in unnatural hosts, while both short and pear-shaped haptomonads were abundant, along with paramastigotes in natural hosts. Haptomonad paramastigotes and pear-shaped promastigotes colonized the esophagus, while paramastigotes predominated in the pharynx. Metacyclics were free-swimming in the lumen of the foregut.

Acquired immunity to larvae of Amblyomma marmoreum and A.hebraeum by tortoises, guinea-pigs and guinea-fowl.

A study of acquired resistance in guinea-pigs, guinea-fowl and tortoises to larvae of the ticks Amblyomma hebraeum Koch and A.marmoreum Koch (Acari: Ixodidae) showed that repeated infestations of the laboratory host resulted in a 29.3-49.4% reduction respectively in weight of engorged larvae. No resistance was induced in guinea-fowl, the natural host for larvae of both species. A small decline in the mean weight of engorged larvae was observed for both species of ticks after three successive infestations on tortoises. The reduction in weight was more pronounced in A.hebraeum (14.5%) which does not naturally feed on tortoises than for A.marmoreum (8.4%), a common tick on this host. The occurrence of acquired resistance in natural tick host relationships as opposed to unnatural tick host relationships is discussed.

Refractory barriers in the sand fly Phlebotomus papatasi (Diptera: Psychodidae) to infection with Leishmania panamensis.

The life cycle of Leishmania panamensis in Phlebotomus papatasi was studied to characterize barriers limiting parasite colonization, differentiation, migration, and attachment in an unnatural sand fly host. The insects were fed a suspension of L. panamensis-infected macrophages and human erythrocytes, and were examined up to 16 days post-infection by light and electron microscopy. Histologic examination of 401 flies showed the peritrophic membrane to be the first important barrier to parasite establishment in the gut lumen. In most flies, parasites were unable to escape from the closed peritrophic sac, which was either excreted or retained intact in the midgut. After five days, only 31% of the flies were infected; attached parasites colonized the pylorus-ileum and/or colon regions of the hindgut. Anterior migration into the cardia region of the midgut occurred in less than 1% of infected flies; no parasites colonized the foregut. In the bloodmeal and residual bloodmeal, five morphologic forms developed from ingested amastigotes: stumpy, spatulate, elongate, short nectomonad promastigotes, and paramastigotes. Abnormal retention of amastigotes in macrophages and delayed development of promastigote stages was observed. The primary form attached in the hindgut was a pear-shaped haptomonad promastigote. Differentiation of L. panamensis in Ph. papatasi appeared to be similar to that described in natural hosts, except that metacyclic infective forms were not observed, and some forms developed in unusual locations. Phlebotomus papatasi was a partly refractory biological host for L. panamensis. The peritrophic membrane adversely affected the infection rate; rare anterior migration and a lack of metacyclic promastigotes may preclude transmission by bite.

The Mouse Model and Understanding Immunity to Herpes Simplex Virus

Investigation of the immune response to herpes simplex virus (HSV) has progressed rapidly, mainly through the use of various animal models of human disease. Murine models of HSV infection have been explored extensively and have yielded a wide array of insights into the mechanisms of antiviral immunity. Current research has focused on defining the role of individual viral envelope glycoproteins in stimulating a protective B and T cell response, with the ultimate goal of identifying the minimum effective immunization unit. This ongoing dissection of the glycoprotein-specific immune response in the mouse has revealed both the values of an animal model that mimics human infection and the limitations inherent in defining the immunopotential of specific viral proteins and peptides in an unnatural host. This article reviews the results of murine studies evaluating the mechanisms of protection against HSV infection and the protective potential of immunization with the viral envelope glycoproteins.

Surface Ultrastructure of Adults and Eggs of Gnathostoma spinigerum (Nematoda: Gnathostomatidae)

Adult specimens Gnathostoma spinigerum were examined by scanning electron microscopy (SEM). Worms had an anterior head-bulb with one pair of lateral lips. The head-bulb was armed with 7-10 transverse rows of hooks. On the anterior one-half of the worms, multidigitate cuticular spines are spaced unevenly on the outer edge of transverse striations. Small unidentate cuticular spines also are located on the posterior one-half of the body. Other structures included labial papillae, amphids, cervical papillae, an excretory pore, caudal papillae, small flat papillae, and phasmids. Eggs from the uteri of female worms are covered with pits of irregular size, shape, and depth. Gnathostoma spinigerum Owen, 1836 is widely distributed in Southeast Asia and South America and is one of the etiological agents of human gnathostomiasis. Adult worms are normally found in nodules of the stomach wall of feline and canine hosts. Man is an unnatural host for this helminth. When accidental infections do occur, the worms often undergo extensive larval migrations and usually do not reach maturity. Morphology of adult stages of G. spinigerum have been studied in detail by light microscopy (Daengsvang, 1981; Lin & Chen, 1986; Miyazaki, 1954; Takeichi, 1956). Scanning electron microscopical (SEM) studies are few; there are only two brief descriptions of the surface morphology of eggs of this helminth (Ishii & Tokunaga, 1970; Ratanarapee, 1982; Ratanarapee & Jesadapatarakul, 1982; Ratanarapee et al., 1988; Scholz & Ditrich, 1990; Zaman, 1987). We report detailed observations of the external surface of the adult stages and eggs of G. spinigerum using SEM. MATERIALS AND METHODS Six adult specimens of Gnathostoma spinigerum were obtained from dogs that were infected experimentally with advanced third-stage larvae obtained in Thailand. Eggs were removed from the uteri of gravid female worms. Viable adult male and female worms were washed in several changes of tap water and soaked in physiological saline. The worms were fixed in 10% formalin for at least one week, washed in running tap water overnight to remove the fixative, and transferred to distilled water. Specimens were rinsed twice in Millonig's phosphate buffer and postfixed in 1% Os04 for 3 h. During postfixation, worms were cut transversely into seven pieces to facilitate observations by SEM. These pieces were dehydrated in an ascending series of ethanol, transferred into amyl acetate, and critical-point dried with a Hitachi HCP-2 critical-point dryer. 1 The authors express their gratitude to Dr. C. T. Atkinson, Institute of Pathology, Case Western Reserve University, for his critical reading of the manuscript. TRANS. AM. MICROSC. SOC., 110(4): 315-320. 1991. ? Copyright, 1991, by the American Microscopical Society, Inc. This content downloaded from 157.55.39.127 on Tue, 28 Jun 2016 06:58:21 UTC All use subject to http://about.jstor.org/terms TRANS. AM. MICROSC. SOC.

The fate of Hepatozoon species naturally infecting florida black racers and watersnakes in potential mosquito and soft tick vectors, and histological evidence of pathogenicity in unnatural host species

Haemogregarine parasites, derived from the Florida snakes Coluber constrictor and Nerodia fasciata and ingested by Aedes aegypti, completed sporogony within the hemocoeles of nearly all fed mosquitoes in 14–18 days, and produced oocysts typlcal of Hepatozoon. However, mortalities and morbidity were high in the Culex which had fed on the Coluber. Oocysts were not found in any Ornithodoros turicata (Argasidae) which fed upon either snake host, but many sections of fed ticks had gametocyte-like cells within the gut lumen. Most lizards, Anolis carolinensis and Anolis sagrei, infected per os with oocysts derived from both snake species developed infections. Infections in the lizards were largely confined to hepatic schizonts with few parasites found in erythrocytes. Unlike naturally infected snake hosts, Hepatozoon schizonts in livers of lizards were often either surrounded by an unidentified dark pigment or heavily infiltrated with mononuclear inflammatory cells.